OSCL-LXR linux-6.0.1/​drivers/​gpu/​drm/​drm_bridge.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 /*
  * Copyright (c) 2014 Samsung Electronics Co., Ltd
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sub license,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice (including the
  * next paragraph) shall be included in all copies or substantial portions
  * of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  * DEALINGS IN THE SOFTWARE.
  */
 
 #include <linux/err.h>
 #include <linux/media-bus-format.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 
 #include <drm/drm_atomic_state_helper.h>
 #include <drm/drm_bridge.h>
 #include <drm/drm_encoder.h>
 #include <drm/drm_of.h>
 #include <drm/drm_print.h>
 
 #include "drm_crtc_internal.h"
 
 /**
  * DOC: overview
  *
  * &struct drm_bridge represents a device that hangs on to an encoder. These are
  * handy when a regular &drm_encoder entity isn't enough to represent the entire
  * encoder chain.
  *
  * A bridge is always attached to a single &drm_encoder at a time, but can be
  * either connected to it directly, or through a chain of bridges::
  *
  *     [ CRTC ---> ] Encoder ---> Bridge A ---> Bridge B
  *
  * Here, the output of the encoder feeds to bridge A, and that furthers feeds to
  * bridge B. Bridge chains can be arbitrarily long, and shall be fully linear:
  * Chaining multiple bridges to the output of a bridge, or the same bridge to
  * the output of different bridges, is not supported.
  *
  * &drm_bridge, like &drm_panel, aren't &drm_mode_object entities like planes,
  * CRTCs, encoders or connectors and hence are not visible to userspace. They
  * just provide additional hooks to get the desired output at the end of the
  * encoder chain.
  */
 
 /**
  * DOC: display driver integration
  *
  * Display drivers are responsible for linking encoders with the first bridge
  * in the chains. This is done by acquiring the appropriate bridge with
  * devm_drm_of_get_bridge(). Once acquired, the bridge shall be attached to the
  * encoder with a call to drm_bridge_attach().
  *
  * Bridges are responsible for linking themselves with the next bridge in the
  * chain, if any. This is done the same way as for encoders, with the call to
  * drm_bridge_attach() occurring in the &drm_bridge_funcs.attach operation.
  *
  * Once these links are created, the bridges can participate along with encoder
  * functions to perform mode validation and fixup (through
  * drm_bridge_chain_mode_valid() and drm_atomic_bridge_chain_check()), mode
  * setting (through drm_bridge_chain_mode_set()), enable (through
  * drm_atomic_bridge_chain_pre_enable() and drm_atomic_bridge_chain_enable())
  * and disable (through drm_atomic_bridge_chain_disable() and
  * drm_atomic_bridge_chain_post_disable()). Those functions call the
  * corresponding operations provided in &drm_bridge_funcs in sequence for all
  * bridges in the chain.
  *
  * For display drivers that use the atomic helpers
  * drm_atomic_helper_check_modeset(),
  * drm_atomic_helper_commit_modeset_enables() and
  * drm_atomic_helper_commit_modeset_disables() (either directly in hand-rolled
  * commit check and commit tail handlers, or through the higher-level
  * drm_atomic_helper_check() and drm_atomic_helper_commit_tail() or
  * drm_atomic_helper_commit_tail_rpm() helpers), this is done transparently and
  * requires no intervention from the driver. For other drivers, the relevant
  * DRM bridge chain functions shall be called manually.
  *
  * Bridges also participate in implementing the &drm_connector at the end of
  * the bridge chain. Display drivers may use the drm_bridge_connector_init()
  * helper to create the &drm_connector, or implement it manually on top of the
  * connector-related operations exposed by the bridge (see the overview
  * documentation of bridge operations for more details).
  */
 
 /**
  * DOC: special care dsi
  *
  * The interaction between the bridges and other frameworks involved in
  * the probing of the upstream driver and the bridge driver can be
  * challenging. Indeed, there's multiple cases that needs to be
  * considered:
  *
  * - The upstream driver doesn't use the component framework and isn't a
  *   MIPI-DSI host. In this case, the bridge driver will probe at some
  *   point and the upstream driver should try to probe again by returning
  *   EPROBE_DEFER as long as the bridge driver hasn't probed.
  *
  * - The upstream driver doesn't use the component framework, but is a
  *   MIPI-DSI host. The bridge device uses the MIPI-DCS commands to be
  *   controlled. In this case, the bridge device is a child of the
  *   display device and when it will probe it's assured that the display
  *   device (and MIPI-DSI host) is present. The upstream driver will be
  *   assured that the bridge driver is connected between the
  *   &mipi_dsi_host_ops.attach and &mipi_dsi_host_ops.detach operations.
  *   Therefore, it must run mipi_dsi_host_register() in its probe
  *   function, and then run drm_bridge_attach() in its
  *   &mipi_dsi_host_ops.attach hook.
  *
  * - The upstream driver uses the component framework and is a MIPI-DSI
  *   host. The bridge device uses the MIPI-DCS commands to be
  *   controlled. This is the same situation than above, and can run
  *   mipi_dsi_host_register() in either its probe or bind hooks.
  *
  * - The upstream driver uses the component framework and is a MIPI-DSI
  *   host. The bridge device uses a separate bus (such as I2C) to be
  *   controlled. In this case, there's no correlation between the probe
  *   of the bridge and upstream drivers, so care must be taken to avoid
  *   an endless EPROBE_DEFER loop, with each driver waiting for the
  *   other to probe.
  *
  * The ideal pattern to cover the last item (and all the others in the
  * MIPI-DSI host driver case) is to split the operations like this:
  *
  * - The MIPI-DSI host driver must run mipi_dsi_host_register() in its
  *   probe hook. It will make sure that the MIPI-DSI host sticks around,
  *   and that the driver's bind can be called.
  *
  * - In its probe hook, the bridge driver must try to find its MIPI-DSI
  *   host, register as a MIPI-DSI device and attach the MIPI-DSI device
  *   to its host. The bridge driver is now functional.
  *
  * - In its &struct mipi_dsi_host_ops.attach hook, the MIPI-DSI host can
  *   now add its component. Its bind hook will now be called and since
  *   the bridge driver is attached and registered, we can now look for
  *   and attach it.
  *
  * At this point, we're now certain that both the upstream driver and
  * the bridge driver are functional and we can't have a deadlock-like
  * situation when probing.
  */
 
 static DEFINE_MUTEX(bridge_lock);
 static LIST_HEAD(bridge_list);
 
 /**
  * drm_bridge_add - add the given bridge to the global bridge list
  *
  * @bridge: bridge control structure
  */
 void drm_bridge_add(struct drm_bridge *bridge)
 {
     mutex_init(&bridge->hpd_mutex);
 
     mutex_lock(&bridge_lock);
     list_add_tail(&bridge->list, &bridge_list);
     mutex_unlock(&bridge_lock);
 }
 EXPORT_SYMBOL(drm_bridge_add);
 
 static void drm_bridge_remove_void(void *bridge)
 {
     drm_bridge_remove(bridge);
 }
 
 /**
  * devm_drm_bridge_add - devm managed version of drm_bridge_add()
  *
  * @dev: device to tie the bridge lifetime to
  * @bridge: bridge control structure
  *
  * This is the managed version of drm_bridge_add() which automatically
  * calls drm_bridge_remove() when @dev is unbound.
  *
  * Return: 0 if no error or negative error code.
  */
 int devm_drm_bridge_add(struct device *dev, struct drm_bridge *bridge)
 {
     drm_bridge_add(bridge);
     return devm_add_action_or_reset(dev, drm_bridge_remove_void, bridge);
 }
 EXPORT_SYMBOL(devm_drm_bridge_add);
 
 /**
  * drm_bridge_remove - remove the given bridge from the global bridge list
  *
  * @bridge: bridge control structure
  */
 void drm_bridge_remove(struct drm_bridge *bridge)
 {
     mutex_lock(&bridge_lock);
     list_del_init(&bridge->list);
     mutex_unlock(&bridge_lock);
 
     mutex_destroy(&bridge->hpd_mutex);
 }
 EXPORT_SYMBOL(drm_bridge_remove);
 
 static struct drm_private_state *
 drm_bridge_atomic_duplicate_priv_state(struct drm_private_obj *obj)
 {
     struct drm_bridge *bridge = drm_priv_to_bridge(obj);
     struct drm_bridge_state *state;
 
     state = bridge->funcs->atomic_duplicate_state(bridge);
     return state ? &state->base : NULL;
 }
 
 static void
 drm_bridge_atomic_destroy_priv_state(struct drm_private_obj *obj,
                      struct drm_private_state *s)
 {
     struct drm_bridge_state *state = drm_priv_to_bridge_state(s);
     struct drm_bridge *bridge = drm_priv_to_bridge(obj);
 
     bridge->funcs->atomic_destroy_state(bridge, state);
 }
 
 static const struct drm_private_state_funcs drm_bridge_priv_state_funcs = {
     .atomic_duplicate_state = drm_bridge_atomic_duplicate_priv_state,
     .atomic_destroy_state = drm_bridge_atomic_destroy_priv_state,
 };
 
 /**
  * drm_bridge_attach - attach the bridge to an encoder's chain
  *
  * @encoder: DRM encoder
  * @bridge: bridge to attach
  * @previous: previous bridge in the chain (optional)
  * @flags: DRM_BRIDGE_ATTACH_* flags
  *
  * Called by a kms driver to link the bridge to an encoder's chain. The previous
  * argument specifies the previous bridge in the chain. If NULL, the bridge is
  * linked directly at the encoder's output. Otherwise it is linked at the
  * previous bridge's output.
  *
  * If non-NULL the previous bridge must be already attached by a call to this
  * function.
  *
  * Note that bridges attached to encoders are auto-detached during encoder
  * cleanup in drm_encoder_cleanup(), so drm_bridge_attach() should generally
  * *not* be balanced with a drm_bridge_detach() in driver code.
  *
  * RETURNS:
  * Zero on success, error code on failure
  */
 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
               struct drm_bridge *previous,
               enum drm_bridge_attach_flags flags)
 {
     int ret;
 
     if (!encoder || !bridge)
         return -EINVAL;
 
     if (previous && (!previous->dev || previous->encoder != encoder))
         return -EINVAL;
 
     if (bridge->dev)
         return -EBUSY;
 
     bridge->dev = encoder->dev;
     bridge->encoder = encoder;
 
     if (previous)
         list_add(&bridge->chain_node, &previous->chain_node);
     else
         list_add(&bridge->chain_node, &encoder->bridge_chain);
 
     if (bridge->funcs->attach) {
         ret = bridge->funcs->attach(bridge, flags);
         if (ret < 0)
             goto err_reset_bridge;
     }
 
     if (bridge->funcs->atomic_reset) {
         struct drm_bridge_state *state;
 
         state = bridge->funcs->atomic_reset(bridge);
         if (IS_ERR(state)) {
             ret = PTR_ERR(state);
             goto err_detach_bridge;
         }
 
         drm_atomic_private_obj_init(bridge->dev, &bridge->base,
                         &state->base,
                         &drm_bridge_priv_state_funcs);
     }
 
     return 0;
 
 err_detach_bridge:
     if (bridge->funcs->detach)
         bridge->funcs->detach(bridge);
 
 err_reset_bridge:
     bridge->dev = NULL;
     bridge->encoder = NULL;
     list_del(&bridge->chain_node);
 
 #ifdef CONFIG_OF
     DRM_ERROR("failed to attach bridge %pOF to encoder %s: %d\n",
           bridge->of_node, encoder->name, ret);
 #else
     DRM_ERROR("failed to attach bridge to encoder %s: %d\n",
           encoder->name, ret);
 #endif
 
     return ret;
 }
 EXPORT_SYMBOL(drm_bridge_attach);
 
 void drm_bridge_detach(struct drm_bridge *bridge)
 {
     if (WARN_ON(!bridge))
         return;
 
     if (WARN_ON(!bridge->dev))
         return;
 
     if (bridge->funcs->atomic_reset)
         drm_atomic_private_obj_fini(&bridge->base);
 
     if (bridge->funcs->detach)
         bridge->funcs->detach(bridge);
 
     list_del(&bridge->chain_node);
     bridge->dev = NULL;
 }
 
 /**
  * DOC: bridge operations
  *
  * Bridge drivers expose operations through the &drm_bridge_funcs structure.
  * The DRM internals (atomic and CRTC helpers) use the helpers defined in
  * drm_bridge.c to call bridge operations. Those operations are divided in
  * three big categories to support different parts of the bridge usage.
  *
  * - The encoder-related operations support control of the bridges in the
  *   chain, and are roughly counterparts to the &drm_encoder_helper_funcs
  *   operations. They are used by the legacy CRTC and the atomic modeset
  *   helpers to perform mode validation, fixup and setting, and enable and
  *   disable the bridge automatically.
  *
  *   The enable and disable operations are split in
  *   &drm_bridge_funcs.pre_enable, &drm_bridge_funcs.enable,
  *   &drm_bridge_funcs.disable and &drm_bridge_funcs.post_disable to provide
  *   finer-grained control.
  *
  *   Bridge drivers may implement the legacy version of those operations, or
  *   the atomic version (prefixed with atomic\_), in which case they shall also
  *   implement the atomic state bookkeeping operations
  *   (&drm_bridge_funcs.atomic_duplicate_state,
  *   &drm_bridge_funcs.atomic_destroy_state and &drm_bridge_funcs.reset).
  *   Mixing atomic and non-atomic versions of the operations is not supported.
  *
  * - The bus format negotiation operations
  *   &drm_bridge_funcs.atomic_get_output_bus_fmts and
  *   &drm_bridge_funcs.atomic_get_input_bus_fmts allow bridge drivers to
  *   negotiate the formats transmitted between bridges in the chain when
  *   multiple formats are supported. Negotiation for formats is performed
  *   transparently for display drivers by the atomic modeset helpers. Only
  *   atomic versions of those operations exist, bridge drivers that need to
  *   implement them shall thus also implement the atomic version of the
  *   encoder-related operations. This feature is not supported by the legacy
  *   CRTC helpers.
  *
  * - The connector-related operations support implementing a &drm_connector
  *   based on a chain of bridges. DRM bridges traditionally create a
  *   &drm_connector for bridges meant to be used at the end of the chain. This
  *   puts additional burden on bridge drivers, especially for bridges that may
  *   be used in the middle of a chain or at the end of it. Furthermore, it
  *   requires all operations of the &drm_connector to be handled by a single
  *   bridge, which doesn't always match the hardware architecture.
  *
  *   To simplify bridge drivers and make the connector implementation more
  *   flexible, a new model allows bridges to unconditionally skip creation of
  *   &drm_connector and instead expose &drm_bridge_funcs operations to support
  *   an externally-implemented &drm_connector. Those operations are
  *   &drm_bridge_funcs.detect, &drm_bridge_funcs.get_modes,
  *   &drm_bridge_funcs.get_edid, &drm_bridge_funcs.hpd_notify,
  *   &drm_bridge_funcs.hpd_enable and &drm_bridge_funcs.hpd_disable. When
  *   implemented, display drivers shall create a &drm_connector instance for
  *   each chain of bridges, and implement those connector instances based on
  *   the bridge connector operations.
  *
  *   Bridge drivers shall implement the connector-related operations for all
  *   the features that the bridge hardware support. For instance, if a bridge
  *   supports reading EDID, the &drm_bridge_funcs.get_edid shall be
  *   implemented. This however doesn't mean that the DDC lines are wired to the
  *   bridge on a particular platform, as they could also be connected to an I2C
  *   controller of the SoC. Support for the connector-related operations on the
  *   running platform is reported through the &drm_bridge.ops flags. Bridge
  *   drivers shall detect which operations they can support on the platform
  *   (usually this information is provided by ACPI or DT), and set the
  *   &drm_bridge.ops flags for all supported operations. A flag shall only be
  *   set if the corresponding &drm_bridge_funcs operation is implemented, but
  *   an implemented operation doesn't necessarily imply that the corresponding
  *   flag will be set. Display drivers shall use the &drm_bridge.ops flags to
  *   decide which bridge to delegate a connector operation to. This mechanism
  *   allows providing a single static const &drm_bridge_funcs instance in
  *   bridge drivers, improving security by storing function pointers in
  *   read-only memory.
  *
  *   In order to ease transition, bridge drivers may support both the old and
  *   new models by making connector creation optional and implementing the
  *   connected-related bridge operations. Connector creation is then controlled
  *   by the flags argument to the drm_bridge_attach() function. Display drivers
  *   that support the new model and create connectors themselves shall set the
  *   %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag, and bridge drivers shall then skip
  *   connector creation. For intermediate bridges in the chain, the flag shall
  *   be passed to the drm_bridge_attach() call for the downstream bridge.
  *   Bridge drivers that implement the new model only shall return an error
  *   from their &drm_bridge_funcs.attach handler when the
  *   %DRM_BRIDGE_ATTACH_NO_CONNECTOR flag is not set. New display drivers
  *   should use the new model, and convert the bridge drivers they use if
  *   needed, in order to gradually transition to the new model.
  */
 
 /**
  * drm_bridge_chain_mode_fixup - fixup proposed mode for all bridges in the
  *               encoder chain
  * @bridge: bridge control structure
  * @mode: desired mode to be set for the bridge
  * @adjusted_mode: updated mode that works for this bridge
  *
  * Calls &drm_bridge_funcs.mode_fixup for all the bridges in the
  * encoder chain, starting from the first bridge to the last.
  *
  * Note: the bridge passed should be the one closest to the encoder
  *
  * RETURNS:
  * true on success, false on failure
  */
 bool drm_bridge_chain_mode_fixup(struct drm_bridge *bridge,
                  const struct drm_display_mode *mode,
                  struct drm_display_mode *adjusted_mode)
 {
     struct drm_encoder *encoder;
 
     if (!bridge)
         return true;
 
     encoder = bridge->encoder;
     list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
         if (!bridge->funcs->mode_fixup)
             continue;
 
         if (!bridge->funcs->mode_fixup(bridge, mode, adjusted_mode))
             return false;
     }
 
     return true;
 }
 EXPORT_SYMBOL(drm_bridge_chain_mode_fixup);
 
 /**
  * drm_bridge_chain_mode_valid - validate the mode against all bridges in the
  *               encoder chain.
  * @bridge: bridge control structure
  * @info: display info against which the mode shall be validated
  * @mode: desired mode to be validated
  *
  * Calls &drm_bridge_funcs.mode_valid for all the bridges in the encoder
  * chain, starting from the first bridge to the last. If at least one bridge
  * does not accept the mode the function returns the error code.
  *
  * Note: the bridge passed should be the one closest to the encoder.
  *
  * RETURNS:
  * MODE_OK on success, drm_mode_status Enum error code on failure
  */
 enum drm_mode_status
 drm_bridge_chain_mode_valid(struct drm_bridge *bridge,
                 const struct drm_display_info *info,
                 const struct drm_display_mode *mode)
 {
     struct drm_encoder *encoder;
 
     if (!bridge)
         return MODE_OK;
 
     encoder = bridge->encoder;
     list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
         enum drm_mode_status ret;
 
         if (!bridge->funcs->mode_valid)
             continue;
 
         ret = bridge->funcs->mode_valid(bridge, info, mode);
         if (ret != MODE_OK)
             return ret;
     }
 
     return MODE_OK;
 }
 EXPORT_SYMBOL(drm_bridge_chain_mode_valid);
 
 /**
  * drm_bridge_chain_disable - disables all bridges in the encoder chain
  * @bridge: bridge control structure
  *
  * Calls &drm_bridge_funcs.disable op for all the bridges in the encoder
  * chain, starting from the last bridge to the first. These are called before
  * calling the encoder's prepare op.
  *
  * Note: the bridge passed should be the one closest to the encoder
  */
 void drm_bridge_chain_disable(struct drm_bridge *bridge)
 {
     struct drm_encoder *encoder;
     struct drm_bridge *iter;
 
     if (!bridge)
         return;
 
     encoder = bridge->encoder;
     list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
         if (iter->funcs->disable)
             iter->funcs->disable(iter);
 
         if (iter == bridge)
             break;
     }
 }
 EXPORT_SYMBOL(drm_bridge_chain_disable);
 
 /**
  * drm_bridge_chain_post_disable - cleans up after disabling all bridges in the
  *                 encoder chain
  * @bridge: bridge control structure
  *
  * Calls &drm_bridge_funcs.post_disable op for all the bridges in the
  * encoder chain, starting from the first bridge to the last. These are called
  * after completing the encoder's prepare op.
  *
  * Note: the bridge passed should be the one closest to the encoder
  */
 void drm_bridge_chain_post_disable(struct drm_bridge *bridge)
 {
     struct drm_encoder *encoder;
 
     if (!bridge)
         return;
 
     encoder = bridge->encoder;
     list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
         if (bridge->funcs->post_disable)
             bridge->funcs->post_disable(bridge);
     }
 }
 EXPORT_SYMBOL(drm_bridge_chain_post_disable);
 
 /**
  * drm_bridge_chain_mode_set - set proposed mode for all bridges in the
  *                 encoder chain
  * @bridge: bridge control structure
  * @mode: desired mode to be set for the encoder chain
  * @adjusted_mode: updated mode that works for this encoder chain
  *
  * Calls &drm_bridge_funcs.mode_set op for all the bridges in the
  * encoder chain, starting from the first bridge to the last.
  *
  * Note: the bridge passed should be the one closest to the encoder
  */
 void drm_bridge_chain_mode_set(struct drm_bridge *bridge,
                    const struct drm_display_mode *mode,
                    const struct drm_display_mode *adjusted_mode)
 {
     struct drm_encoder *encoder;
 
     if (!bridge)
         return;
 
     encoder = bridge->encoder;
     list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
         if (bridge->funcs->mode_set)
             bridge->funcs->mode_set(bridge, mode, adjusted_mode);
     }
 }
 EXPORT_SYMBOL(drm_bridge_chain_mode_set);
 
 /**
  * drm_bridge_chain_pre_enable - prepares for enabling all bridges in the
  *               encoder chain
  * @bridge: bridge control structure
  *
  * Calls &drm_bridge_funcs.pre_enable op for all the bridges in the encoder
  * chain, starting from the last bridge to the first. These are called
  * before calling the encoder's commit op.
  *
  * Note: the bridge passed should be the one closest to the encoder
  */
 void drm_bridge_chain_pre_enable(struct drm_bridge *bridge)
 {
     struct drm_encoder *encoder;
     struct drm_bridge *iter;
 
     if (!bridge)
         return;
 
     encoder = bridge->encoder;
     list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
         if (iter->funcs->pre_enable)
             iter->funcs->pre_enable(iter);
 
         if (iter == bridge)
             break;
     }
 }
 EXPORT_SYMBOL(drm_bridge_chain_pre_enable);
 
 /**
  * drm_bridge_chain_enable - enables all bridges in the encoder chain
  * @bridge: bridge control structure
  *
  * Calls &drm_bridge_funcs.enable op for all the bridges in the encoder
  * chain, starting from the first bridge to the last. These are called
  * after completing the encoder's commit op.
  *
  * Note that the bridge passed should be the one closest to the encoder
  */
 void drm_bridge_chain_enable(struct drm_bridge *bridge)
 {
     struct drm_encoder *encoder;
 
     if (!bridge)
         return;
 
     encoder = bridge->encoder;
     list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
         if (bridge->funcs->enable)
             bridge->funcs->enable(bridge);
     }
 }
 EXPORT_SYMBOL(drm_bridge_chain_enable);
 
 /**
  * drm_atomic_bridge_chain_disable - disables all bridges in the encoder chain
  * @bridge: bridge control structure
  * @old_state: old atomic state
  *
  * Calls &drm_bridge_funcs.atomic_disable (falls back on
  * &drm_bridge_funcs.disable) op for all the bridges in the encoder chain,
  * starting from the last bridge to the first. These are called before calling
  * &drm_encoder_helper_funcs.atomic_disable
  *
  * Note: the bridge passed should be the one closest to the encoder
  */
 void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,
                      struct drm_atomic_state *old_state)
 {
     struct drm_encoder *encoder;
     struct drm_bridge *iter;
 
     if (!bridge)
         return;
 
     encoder = bridge->encoder;
     list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
         if (iter->funcs->atomic_disable) {
             struct drm_bridge_state *old_bridge_state;
 
             old_bridge_state =
                 drm_atomic_get_old_bridge_state(old_state,
                                 iter);
             if (WARN_ON(!old_bridge_state))
                 return;
 
             iter->funcs->atomic_disable(iter, old_bridge_state);
         } else if (iter->funcs->disable) {
             iter->funcs->disable(iter);
         }
 
         if (iter == bridge)
             break;
     }
 }
 EXPORT_SYMBOL(drm_atomic_bridge_chain_disable);
 
 /**
  * drm_atomic_bridge_chain_post_disable - cleans up after disabling all bridges
  *                    in the encoder chain
  * @bridge: bridge control structure
  * @old_state: old atomic state
  *
  * Calls &drm_bridge_funcs.atomic_post_disable (falls back on
  * &drm_bridge_funcs.post_disable) op for all the bridges in the encoder chain,
  * starting from the first bridge to the last. These are called after completing
  * &drm_encoder_helper_funcs.atomic_disable
  *
  * Note: the bridge passed should be the one closest to the encoder
  */
 void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
                       struct drm_atomic_state *old_state)
 {
     struct drm_encoder *encoder;
 
     if (!bridge)
         return;
 
     encoder = bridge->encoder;
     list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
         if (bridge->funcs->atomic_post_disable) {
             struct drm_bridge_state *old_bridge_state;
 
             old_bridge_state =
                 drm_atomic_get_old_bridge_state(old_state,
                                 bridge);
             if (WARN_ON(!old_bridge_state))
                 return;
 
             bridge->funcs->atomic_post_disable(bridge,
                                old_bridge_state);
         } else if (bridge->funcs->post_disable) {
             bridge->funcs->post_disable(bridge);
         }
     }
 }
 EXPORT_SYMBOL(drm_atomic_bridge_chain_post_disable);
 
 /**
  * drm_atomic_bridge_chain_pre_enable - prepares for enabling all bridges in
  *                  the encoder chain
  * @bridge: bridge control structure
  * @old_state: old atomic state
  *
  * Calls &drm_bridge_funcs.atomic_pre_enable (falls back on
  * &drm_bridge_funcs.pre_enable) op for all the bridges in the encoder chain,
  * starting from the last bridge to the first. These are called before calling
  * &drm_encoder_helper_funcs.atomic_enable
  *
  * Note: the bridge passed should be the one closest to the encoder
  */
 void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,
                     struct drm_atomic_state *old_state)
 {
     struct drm_encoder *encoder;
     struct drm_bridge *iter;
 
     if (!bridge)
         return;
 
     encoder = bridge->encoder;
     list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
         if (iter->funcs->atomic_pre_enable) {
             struct drm_bridge_state *old_bridge_state;
 
             old_bridge_state =
                 drm_atomic_get_old_bridge_state(old_state,
                                 iter);
             if (WARN_ON(!old_bridge_state))
                 return;
 
             iter->funcs->atomic_pre_enable(iter, old_bridge_state);
         } else if (iter->funcs->pre_enable) {
             iter->funcs->pre_enable(iter);
         }
 
         if (iter == bridge)
             break;
     }
 }
 EXPORT_SYMBOL(drm_atomic_bridge_chain_pre_enable);
 
 /**
  * drm_atomic_bridge_chain_enable - enables all bridges in the encoder chain
  * @bridge: bridge control structure
  * @old_state: old atomic state
  *
  * Calls &drm_bridge_funcs.atomic_enable (falls back on
  * &drm_bridge_funcs.enable) op for all the bridges in the encoder chain,
  * starting from the first bridge to the last. These are called after completing
  * &drm_encoder_helper_funcs.atomic_enable
  *
  * Note: the bridge passed should be the one closest to the encoder
  */
 void drm_atomic_bridge_chain_enable(struct drm_bridge *bridge,
                     struct drm_atomic_state *old_state)
 {
     struct drm_encoder *encoder;
 
     if (!bridge)
         return;
 
     encoder = bridge->encoder;
     list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
         if (bridge->funcs->atomic_enable) {
             struct drm_bridge_state *old_bridge_state;
 
             old_bridge_state =
                 drm_atomic_get_old_bridge_state(old_state,
                                 bridge);
             if (WARN_ON(!old_bridge_state))
                 return;
 
             bridge->funcs->atomic_enable(bridge, old_bridge_state);
         } else if (bridge->funcs->enable) {
             bridge->funcs->enable(bridge);
         }
     }
 }
 EXPORT_SYMBOL(drm_atomic_bridge_chain_enable);
 
 static int drm_atomic_bridge_check(struct drm_bridge *bridge,
                    struct drm_crtc_state *crtc_state,
                    struct drm_connector_state *conn_state)
 {
     if (bridge->funcs->atomic_check) {
         struct drm_bridge_state *bridge_state;
         int ret;
 
         bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
                                    bridge);
         if (WARN_ON(!bridge_state))
             return -EINVAL;
 
         ret = bridge->funcs->atomic_check(bridge, bridge_state,
                           crtc_state, conn_state);
         if (ret)
             return ret;
     } else if (bridge->funcs->mode_fixup) {
         if (!bridge->funcs->mode_fixup(bridge, &crtc_state->mode,
                            &crtc_state->adjusted_mode))
             return -EINVAL;
     }
 
     return 0;
 }
 
 static int select_bus_fmt_recursive(struct drm_bridge *first_bridge,
                     struct drm_bridge *cur_bridge,
                     struct drm_crtc_state *crtc_state,
                     struct drm_connector_state *conn_state,
                     u32 out_bus_fmt)
 {
     struct drm_bridge_state *cur_state;
     unsigned int num_in_bus_fmts, i;
     struct drm_bridge *prev_bridge;
     u32 *in_bus_fmts;
     int ret;
 
     prev_bridge = drm_bridge_get_prev_bridge(cur_bridge);
     cur_state = drm_atomic_get_new_bridge_state(crtc_state->state,
                             cur_bridge);
 
     /*
      * If bus format negotiation is not supported by this bridge, let's
      * pass MEDIA_BUS_FMT_FIXED to the previous bridge in the chain and
      * hope that it can handle this situation gracefully (by providing
      * appropriate default values).
      */
     if (!cur_bridge->funcs->atomic_get_input_bus_fmts) {
         if (cur_bridge != first_bridge) {
             ret = select_bus_fmt_recursive(first_bridge,
                                prev_bridge, crtc_state,
                                conn_state,
                                MEDIA_BUS_FMT_FIXED);
             if (ret)
                 return ret;
         }
 
         /*
          * Driver does not implement the atomic state hooks, but that's
          * fine, as long as it does not access the bridge state.
          */
         if (cur_state) {
             cur_state->input_bus_cfg.format = MEDIA_BUS_FMT_FIXED;
             cur_state->output_bus_cfg.format = out_bus_fmt;
         }
 
         return 0;
     }
 
     /*
      * If the driver implements ->atomic_get_input_bus_fmts() it
      * should also implement the atomic state hooks.
      */
     if (WARN_ON(!cur_state))
         return -EINVAL;
 
     in_bus_fmts = cur_bridge->funcs->atomic_get_input_bus_fmts(cur_bridge,
                             cur_state,
                             crtc_state,
                             conn_state,
                             out_bus_fmt,
                             &num_in_bus_fmts);
     if (!num_in_bus_fmts)
         return -ENOTSUPP;
     else if (!in_bus_fmts)
         return -ENOMEM;
 
     if (first_bridge == cur_bridge) {
         cur_state->input_bus_cfg.format = in_bus_fmts[0];
         cur_state->output_bus_cfg.format = out_bus_fmt;
         kfree(in_bus_fmts);
         return 0;
     }
 
     for (i = 0; i < num_in_bus_fmts; i++) {
         ret = select_bus_fmt_recursive(first_bridge, prev_bridge,
                            crtc_state, conn_state,
                            in_bus_fmts[i]);
         if (ret != -ENOTSUPP)
             break;
     }
 
     if (!ret) {
         cur_state->input_bus_cfg.format = in_bus_fmts[i];
         cur_state->output_bus_cfg.format = out_bus_fmt;
     }
 
     kfree(in_bus_fmts);
     return ret;
 }
 
 /*
  * This function is called by &drm_atomic_bridge_chain_check() just before
  * calling &drm_bridge_funcs.atomic_check() on all elements of the chain.
  * It performs bus format negotiation between bridge elements. The negotiation
  * happens in reverse order, starting from the last element in the chain up to
  * @bridge.
  *
  * Negotiation starts by retrieving supported output bus formats on the last
  * bridge element and testing them one by one. The test is recursive, meaning
  * that for each tested output format, the whole chain will be walked backward,
  * and each element will have to choose an input bus format that can be
  * transcoded to the requested output format. When a bridge element does not
  * support transcoding into a specific output format -ENOTSUPP is returned and
  * the next bridge element will have to try a different format. If none of the
  * combinations worked, -ENOTSUPP is returned and the atomic modeset will fail.
  *
  * This implementation is relying on
  * &drm_bridge_funcs.atomic_get_output_bus_fmts() and
  * &drm_bridge_funcs.atomic_get_input_bus_fmts() to gather supported
  * input/output formats.
  *
  * When &drm_bridge_funcs.atomic_get_output_bus_fmts() is not implemented by
  * the last element of the chain, &drm_atomic_bridge_chain_select_bus_fmts()
  * tries a single format: &drm_connector.display_info.bus_formats[0] if
  * available, MEDIA_BUS_FMT_FIXED otherwise.
  *
  * When &drm_bridge_funcs.atomic_get_input_bus_fmts() is not implemented,
  * &drm_atomic_bridge_chain_select_bus_fmts() skips the negotiation on the
  * bridge element that lacks this hook and asks the previous element in the
  * chain to try MEDIA_BUS_FMT_FIXED. It's up to bridge drivers to decide what
  * to do in that case (fail if they want to enforce bus format negotiation, or
  * provide a reasonable default if they need to support pipelines where not
  * all elements support bus format negotiation).
  */
 static int
 drm_atomic_bridge_chain_select_bus_fmts(struct drm_bridge *bridge,
                     struct drm_crtc_state *crtc_state,
                     struct drm_connector_state *conn_state)
 {
     struct drm_connector *conn = conn_state->connector;
     struct drm_encoder *encoder = bridge->encoder;
     struct drm_bridge_state *last_bridge_state;
     unsigned int i, num_out_bus_fmts;
     struct drm_bridge *last_bridge;
     u32 *out_bus_fmts;
     int ret = 0;
 
     last_bridge = list_last_entry(&encoder->bridge_chain,
                       struct drm_bridge, chain_node);
     last_bridge_state = drm_atomic_get_new_bridge_state(crtc_state->state,
                                 last_bridge);
 
     if (last_bridge->funcs->atomic_get_output_bus_fmts) {
         const struct drm_bridge_funcs *funcs = last_bridge->funcs;
 
         /*
          * If the driver implements ->atomic_get_output_bus_fmts() it
          * should also implement the atomic state hooks.
          */
         if (WARN_ON(!last_bridge_state))
             return -EINVAL;
 
         out_bus_fmts = funcs->atomic_get_output_bus_fmts(last_bridge,
                             last_bridge_state,
                             crtc_state,
                             conn_state,
                             &num_out_bus_fmts);
         if (!num_out_bus_fmts)
             return -ENOTSUPP;
         else if (!out_bus_fmts)
             return -ENOMEM;
     } else {
         num_out_bus_fmts = 1;
         out_bus_fmts = kmalloc(sizeof(*out_bus_fmts), GFP_KERNEL);
         if (!out_bus_fmts)
             return -ENOMEM;
 
         if (conn->display_info.num_bus_formats &&
             conn->display_info.bus_formats)
             out_bus_fmts[0] = conn->display_info.bus_formats[0];
         else
             out_bus_fmts[0] = MEDIA_BUS_FMT_FIXED;
     }
 
     for (i = 0; i < num_out_bus_fmts; i++) {
         ret = select_bus_fmt_recursive(bridge, last_bridge, crtc_state,
                            conn_state, out_bus_fmts[i]);
         if (ret != -ENOTSUPP)
             break;
     }
 
     kfree(out_bus_fmts);
 
     return ret;
 }
 
 static void
 drm_atomic_bridge_propagate_bus_flags(struct drm_bridge *bridge,
                       struct drm_connector *conn,
                       struct drm_atomic_state *state)
 {
     struct drm_bridge_state *bridge_state, *next_bridge_state;
     struct drm_bridge *next_bridge;
     u32 output_flags = 0;
 
     bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
 
     /* No bridge state attached to this bridge => nothing to propagate. */
     if (!bridge_state)
         return;
 
     next_bridge = drm_bridge_get_next_bridge(bridge);
 
     /*
      * Let's try to apply the most common case here, that is, propagate
      * display_info flags for the last bridge, and propagate the input
      * flags of the next bridge element to the output end of the current
      * bridge when the bridge is not the last one.
      * There are exceptions to this rule, like when signal inversion is
      * happening at the board level, but that's something drivers can deal
      * with from their &drm_bridge_funcs.atomic_check() implementation by
      * simply overriding the flags value we've set here.
      */
     if (!next_bridge) {
         output_flags = conn->display_info.bus_flags;
     } else {
         next_bridge_state = drm_atomic_get_new_bridge_state(state,
                                 next_bridge);
         /*
          * No bridge state attached to the next bridge, just leave the
          * flags to 0.
          */
         if (next_bridge_state)
             output_flags = next_bridge_state->input_bus_cfg.flags;
     }
 
     bridge_state->output_bus_cfg.flags = output_flags;
 
     /*
      * Propagate the output flags to the input end of the bridge. Again, it's
      * not necessarily what all bridges want, but that's what most of them
      * do, and by doing that by default we avoid forcing drivers to
      * duplicate the "dummy propagation" logic.
      */
     bridge_state->input_bus_cfg.flags = output_flags;
 }
 
 /**
  * drm_atomic_bridge_chain_check() - Do an atomic check on the bridge chain
  * @bridge: bridge control structure
  * @crtc_state: new CRTC state
  * @conn_state: new connector state
  *
  * First trigger a bus format negotiation before calling
  * &drm_bridge_funcs.atomic_check() (falls back on
  * &drm_bridge_funcs.mode_fixup()) op for all the bridges in the encoder chain,
  * starting from the last bridge to the first. These are called before calling
  * &drm_encoder_helper_funcs.atomic_check()
  *
  * RETURNS:
  * 0 on success, a negative error code on failure
  */
 int drm_atomic_bridge_chain_check(struct drm_bridge *bridge,
                   struct drm_crtc_state *crtc_state,
                   struct drm_connector_state *conn_state)
 {
     struct drm_connector *conn = conn_state->connector;
     struct drm_encoder *encoder;
     struct drm_bridge *iter;
     int ret;
 
     if (!bridge)
         return 0;
 
     ret = drm_atomic_bridge_chain_select_bus_fmts(bridge, crtc_state,
                               conn_state);
     if (ret)
         return ret;
 
     encoder = bridge->encoder;
     list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
         int ret;
 
         /*
          * Bus flags are propagated by default. If a bridge needs to
          * tweak the input bus flags for any reason, it should happen
          * in its &drm_bridge_funcs.atomic_check() implementation such
          * that preceding bridges in the chain can propagate the new
          * bus flags.
          */
         drm_atomic_bridge_propagate_bus_flags(iter, conn,
                               crtc_state->state);
 
         ret = drm_atomic_bridge_check(iter, crtc_state, conn_state);
         if (ret)
             return ret;
 
         if (iter == bridge)
             break;
     }
 
     return 0;
 }
 EXPORT_SYMBOL(drm_atomic_bridge_chain_check);
 
 /**
  * drm_bridge_detect - check if anything is attached to the bridge output
  * @bridge: bridge control structure
  *
  * If the bridge supports output detection, as reported by the
  * DRM_BRIDGE_OP_DETECT bridge ops flag, call &drm_bridge_funcs.detect for the
  * bridge and return the connection status. Otherwise return
  * connector_status_unknown.
  *
  * RETURNS:
  * The detection status on success, or connector_status_unknown if the bridge
  * doesn't support output detection.
  */
 enum drm_connector_status drm_bridge_detect(struct drm_bridge *bridge)
 {
     if (!(bridge->ops & DRM_BRIDGE_OP_DETECT))
         return connector_status_unknown;
 
     return bridge->funcs->detect(bridge);
 }
 EXPORT_SYMBOL_GPL(drm_bridge_detect);
 
 /**
  * drm_bridge_get_modes - fill all modes currently valid for the sink into the
  * @connector
  * @bridge: bridge control structure
  * @connector: the connector to fill with modes
  *
  * If the bridge supports output modes retrieval, as reported by the
  * DRM_BRIDGE_OP_MODES bridge ops flag, call &drm_bridge_funcs.get_modes to
  * fill the connector with all valid modes and return the number of modes
  * added. Otherwise return 0.
  *
  * RETURNS:
  * The number of modes added to the connector.
  */
 int drm_bridge_get_modes(struct drm_bridge *bridge,
              struct drm_connector *connector)
 {
     if (!(bridge->ops & DRM_BRIDGE_OP_MODES))
         return 0;
 
     return bridge->funcs->get_modes(bridge, connector);
 }
 EXPORT_SYMBOL_GPL(drm_bridge_get_modes);
 
 /**
  * drm_bridge_get_edid - get the EDID data of the connected display
  * @bridge: bridge control structure
  * @connector: the connector to read EDID for
  *
  * If the bridge supports output EDID retrieval, as reported by the
  * DRM_BRIDGE_OP_EDID bridge ops flag, call &drm_bridge_funcs.get_edid to
  * get the EDID and return it. Otherwise return NULL.
  *
  * RETURNS:
  * The retrieved EDID on success, or NULL otherwise.
  */
 struct edid *drm_bridge_get_edid(struct drm_bridge *bridge,
                  struct drm_connector *connector)
 {
     if (!(bridge->ops & DRM_BRIDGE_OP_EDID))
         return NULL;
 
     return bridge->funcs->get_edid(bridge, connector);
 }
 EXPORT_SYMBOL_GPL(drm_bridge_get_edid);
 
 /**
  * drm_bridge_hpd_enable - enable hot plug detection for the bridge
  * @bridge: bridge control structure
  * @cb: hot-plug detection callback
  * @data: data to be passed to the hot-plug detection callback
  *
  * Call &drm_bridge_funcs.hpd_enable if implemented and register the given @cb
  * and @data as hot plug notification callback. From now on the @cb will be
  * called with @data when an output status change is detected by the bridge,
  * until hot plug notification gets disabled with drm_bridge_hpd_disable().
  *
  * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
  * bridge->ops. This function shall not be called when the flag is not set.
  *
  * Only one hot plug detection callback can be registered at a time, it is an
  * error to call this function when hot plug detection is already enabled for
  * the bridge.
  */
 void drm_bridge_hpd_enable(struct drm_bridge *bridge,
                void (*cb)(void *data,
                       enum drm_connector_status status),
                void *data)
 {
     if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
         return;
 
     mutex_lock(&bridge->hpd_mutex);
 
     if (WARN(bridge->hpd_cb, "Hot plug detection already enabled\n"))
         goto unlock;
 
     bridge->hpd_cb = cb;
     bridge->hpd_data = data;
 
     if (bridge->funcs->hpd_enable)
         bridge->funcs->hpd_enable(bridge);
 
 unlock:
     mutex_unlock(&bridge->hpd_mutex);
 }
 EXPORT_SYMBOL_GPL(drm_bridge_hpd_enable);
 
 /**
  * drm_bridge_hpd_disable - disable hot plug detection for the bridge
  * @bridge: bridge control structure
  *
  * Call &drm_bridge_funcs.hpd_disable if implemented and unregister the hot
  * plug detection callback previously registered with drm_bridge_hpd_enable().
  * Once this function returns the callback will not be called by the bridge
  * when an output status change occurs.
  *
  * Hot plug detection is supported only if the DRM_BRIDGE_OP_HPD flag is set in
  * bridge->ops. This function shall not be called when the flag is not set.
  */
 void drm_bridge_hpd_disable(struct drm_bridge *bridge)
 {
     if (!(bridge->ops & DRM_BRIDGE_OP_HPD))
         return;
 
     mutex_lock(&bridge->hpd_mutex);
     if (bridge->funcs->hpd_disable)
         bridge->funcs->hpd_disable(bridge);
 
     bridge->hpd_cb = NULL;
     bridge->hpd_data = NULL;
     mutex_unlock(&bridge->hpd_mutex);
 }
 EXPORT_SYMBOL_GPL(drm_bridge_hpd_disable);
 
 /**
  * drm_bridge_hpd_notify - notify hot plug detection events
  * @bridge: bridge control structure
  * @status: output connection status
  *
  * Bridge drivers shall call this function to report hot plug events when they
  * detect a change in the output status, when hot plug detection has been
  * enabled by drm_bridge_hpd_enable().
  *
  * This function shall be called in a context that can sleep.
  */
 void drm_bridge_hpd_notify(struct drm_bridge *bridge,
                enum drm_connector_status status)
 {
     mutex_lock(&bridge->hpd_mutex);
     if (bridge->hpd_cb)
         bridge->hpd_cb(bridge->hpd_data, status);
     mutex_unlock(&bridge->hpd_mutex);
 }
 EXPORT_SYMBOL_GPL(drm_bridge_hpd_notify);
 
 #ifdef CONFIG_OF
 /**
  * of_drm_find_bridge - find the bridge corresponding to the device node in
  *          the global bridge list
  *
  * @np: device node
  *
  * RETURNS:
  * drm_bridge control struct on success, NULL on failure
  */
 struct drm_bridge *of_drm_find_bridge(struct device_node *np)
 {
     struct drm_bridge *bridge;
 
     mutex_lock(&bridge_lock);
 
     list_for_each_entry(bridge, &bridge_list, list) {
         if (bridge->of_node == np) {
             mutex_unlock(&bridge_lock);
             return bridge;
         }
     }
 
     mutex_unlock(&bridge_lock);
     return NULL;
 }
 EXPORT_SYMBOL(of_drm_find_bridge);
 #endif
 
 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");
 MODULE_DESCRIPTION("DRM bridge infrastructure");
 MODULE_LICENSE("GPL and additional rights");

This page was automatically generated by the 2.1.0 LXR engine. The LXR team