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linux/drivers/gpu/drm/drm_panel.c
Douglas Anderson f00bfaca70 drm/panel: Avoid warnings w/ panel-simple/panel-edp at shutdown
At shutdown if you've got a _properly_ coded DRM modeset driver then
you'll get these two warnings at shutdown time:

  Skipping disable of already disabled panel
  Skipping unprepare of already unprepared panel

These warnings are ugly and sound concerning, but they're actually a
sign of a properly working system. That's not great.

We're not ready to get rid of the calls to drm_panel_disable() and
drm_panel_unprepare() because we're not 100% convinced that all DRM
modeset drivers are properly calling drm_atomic_helper_shutdown() or
drm_helper_force_disable_all() at the right times. However, having the
warning show up for correctly working systems is bad.

As a bit of a workaround, add some "if" tests to try to avoid the
warning on correctly working systems. Also add some comments and
update the TODO items in the hopes that future developers won't be too
confused by what's going on here.

Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Acked-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240621134427.1.Ieb287c2c3ee3f6d3b0d5f49b29f746b93621749c@changeid
2024-07-22 09:00:58 -07:00

575 lines
16 KiB
C

/*
* Copyright (C) 2013, NVIDIA Corporation. All rights reserved.
*
* 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/backlight.h>
#include <linux/err.h>
#include <linux/module.h>
#include <drm/drm_crtc.h>
#include <drm/drm_panel.h>
#include <drm/drm_print.h>
static DEFINE_MUTEX(panel_lock);
static LIST_HEAD(panel_list);
/**
* DOC: drm panel
*
* The DRM panel helpers allow drivers to register panel objects with a
* central registry and provide functions to retrieve those panels in display
* drivers.
*
* For easy integration into drivers using the &drm_bridge infrastructure please
* take look at drm_panel_bridge_add() and devm_drm_panel_bridge_add().
*/
/**
* drm_panel_init - initialize a panel
* @panel: DRM panel
* @dev: parent device of the panel
* @funcs: panel operations
* @connector_type: the connector type (DRM_MODE_CONNECTOR_*) corresponding to
* the panel interface
*
* Initialize the panel structure for subsequent registration with
* drm_panel_add().
*/
void drm_panel_init(struct drm_panel *panel, struct device *dev,
const struct drm_panel_funcs *funcs, int connector_type)
{
INIT_LIST_HEAD(&panel->list);
INIT_LIST_HEAD(&panel->followers);
mutex_init(&panel->follower_lock);
panel->dev = dev;
panel->funcs = funcs;
panel->connector_type = connector_type;
}
EXPORT_SYMBOL(drm_panel_init);
/**
* drm_panel_add - add a panel to the global registry
* @panel: panel to add
*
* Add a panel to the global registry so that it can be looked up by display
* drivers.
*/
void drm_panel_add(struct drm_panel *panel)
{
mutex_lock(&panel_lock);
list_add_tail(&panel->list, &panel_list);
mutex_unlock(&panel_lock);
}
EXPORT_SYMBOL(drm_panel_add);
/**
* drm_panel_remove - remove a panel from the global registry
* @panel: DRM panel
*
* Removes a panel from the global registry.
*/
void drm_panel_remove(struct drm_panel *panel)
{
mutex_lock(&panel_lock);
list_del_init(&panel->list);
mutex_unlock(&panel_lock);
}
EXPORT_SYMBOL(drm_panel_remove);
/**
* drm_panel_prepare - power on a panel
* @panel: DRM panel
*
* Calling this function will enable power and deassert any reset signals to
* the panel. After this has completed it is possible to communicate with any
* integrated circuitry via a command bus.
*
* Return: 0 on success or a negative error code on failure.
*/
int drm_panel_prepare(struct drm_panel *panel)
{
struct drm_panel_follower *follower;
int ret;
if (!panel)
return -EINVAL;
if (panel->prepared) {
dev_warn(panel->dev, "Skipping prepare of already prepared panel\n");
return 0;
}
mutex_lock(&panel->follower_lock);
if (panel->funcs && panel->funcs->prepare) {
ret = panel->funcs->prepare(panel);
if (ret < 0)
goto exit;
}
panel->prepared = true;
list_for_each_entry(follower, &panel->followers, list) {
ret = follower->funcs->panel_prepared(follower);
if (ret < 0)
dev_info(panel->dev, "%ps failed: %d\n",
follower->funcs->panel_prepared, ret);
}
ret = 0;
exit:
mutex_unlock(&panel->follower_lock);
return ret;
}
EXPORT_SYMBOL(drm_panel_prepare);
/**
* drm_panel_unprepare - power off a panel
* @panel: DRM panel
*
* Calling this function will completely power off a panel (assert the panel's
* reset, turn off power supplies, ...). After this function has completed, it
* is usually no longer possible to communicate with the panel until another
* call to drm_panel_prepare().
*
* Return: 0 on success or a negative error code on failure.
*/
int drm_panel_unprepare(struct drm_panel *panel)
{
struct drm_panel_follower *follower;
int ret;
if (!panel)
return -EINVAL;
/*
* If you are seeing the warning below it likely means one of two things:
* - Your panel driver incorrectly calls drm_panel_unprepare() in its
* shutdown routine. You should delete this.
* - You are using panel-edp or panel-simple and your DRM modeset
* driver's shutdown() callback happened after the panel's shutdown().
* In this case the warning is harmless though ideally you should
* figure out how to reverse the order of the shutdown() callbacks.
*/
if (!panel->prepared) {
dev_warn(panel->dev, "Skipping unprepare of already unprepared panel\n");
return 0;
}
mutex_lock(&panel->follower_lock);
list_for_each_entry(follower, &panel->followers, list) {
ret = follower->funcs->panel_unpreparing(follower);
if (ret < 0)
dev_info(panel->dev, "%ps failed: %d\n",
follower->funcs->panel_unpreparing, ret);
}
if (panel->funcs && panel->funcs->unprepare) {
ret = panel->funcs->unprepare(panel);
if (ret < 0)
goto exit;
}
panel->prepared = false;
ret = 0;
exit:
mutex_unlock(&panel->follower_lock);
return ret;
}
EXPORT_SYMBOL(drm_panel_unprepare);
/**
* drm_panel_enable - enable a panel
* @panel: DRM panel
*
* Calling this function will cause the panel display drivers to be turned on
* and the backlight to be enabled. Content will be visible on screen after
* this call completes.
*
* Return: 0 on success or a negative error code on failure.
*/
int drm_panel_enable(struct drm_panel *panel)
{
int ret;
if (!panel)
return -EINVAL;
if (panel->enabled) {
dev_warn(panel->dev, "Skipping enable of already enabled panel\n");
return 0;
}
if (panel->funcs && panel->funcs->enable) {
ret = panel->funcs->enable(panel);
if (ret < 0)
return ret;
}
panel->enabled = true;
ret = backlight_enable(panel->backlight);
if (ret < 0)
DRM_DEV_INFO(panel->dev, "failed to enable backlight: %d\n",
ret);
return 0;
}
EXPORT_SYMBOL(drm_panel_enable);
/**
* drm_panel_disable - disable a panel
* @panel: DRM panel
*
* This will typically turn off the panel's backlight or disable the display
* drivers. For smart panels it should still be possible to communicate with
* the integrated circuitry via any command bus after this call.
*
* Return: 0 on success or a negative error code on failure.
*/
int drm_panel_disable(struct drm_panel *panel)
{
int ret;
if (!panel)
return -EINVAL;
/*
* If you are seeing the warning below it likely means one of two things:
* - Your panel driver incorrectly calls drm_panel_disable() in its
* shutdown routine. You should delete this.
* - You are using panel-edp or panel-simple and your DRM modeset
* driver's shutdown() callback happened after the panel's shutdown().
* In this case the warning is harmless though ideally you should
* figure out how to reverse the order of the shutdown() callbacks.
*/
if (!panel->enabled) {
dev_warn(panel->dev, "Skipping disable of already disabled panel\n");
return 0;
}
ret = backlight_disable(panel->backlight);
if (ret < 0)
DRM_DEV_INFO(panel->dev, "failed to disable backlight: %d\n",
ret);
if (panel->funcs && panel->funcs->disable) {
ret = panel->funcs->disable(panel);
if (ret < 0)
return ret;
}
panel->enabled = false;
return 0;
}
EXPORT_SYMBOL(drm_panel_disable);
/**
* drm_panel_get_modes - probe the available display modes of a panel
* @panel: DRM panel
* @connector: DRM connector
*
* The modes probed from the panel are automatically added to the connector
* that the panel is attached to.
*
* Return: The number of modes available from the panel on success, or 0 on
* failure (no modes).
*/
int drm_panel_get_modes(struct drm_panel *panel,
struct drm_connector *connector)
{
if (!panel)
return 0;
if (panel->funcs && panel->funcs->get_modes) {
int num;
num = panel->funcs->get_modes(panel, connector);
if (num > 0)
return num;
}
return 0;
}
EXPORT_SYMBOL(drm_panel_get_modes);
#ifdef CONFIG_OF
/**
* of_drm_find_panel - look up a panel using a device tree node
* @np: device tree node of the panel
*
* Searches the set of registered panels for one that matches the given device
* tree node. If a matching panel is found, return a pointer to it.
*
* Return: A pointer to the panel registered for the specified device tree
* node or an ERR_PTR() if no panel matching the device tree node can be found.
*
* Possible error codes returned by this function:
*
* - EPROBE_DEFER: the panel device has not been probed yet, and the caller
* should retry later
* - ENODEV: the device is not available (status != "okay" or "ok")
*/
struct drm_panel *of_drm_find_panel(const struct device_node *np)
{
struct drm_panel *panel;
if (!of_device_is_available(np))
return ERR_PTR(-ENODEV);
mutex_lock(&panel_lock);
list_for_each_entry(panel, &panel_list, list) {
if (panel->dev->of_node == np) {
mutex_unlock(&panel_lock);
return panel;
}
}
mutex_unlock(&panel_lock);
return ERR_PTR(-EPROBE_DEFER);
}
EXPORT_SYMBOL(of_drm_find_panel);
/**
* of_drm_get_panel_orientation - look up the orientation of the panel through
* the "rotation" binding from a device tree node
* @np: device tree node of the panel
* @orientation: orientation enum to be filled in
*
* Looks up the rotation of a panel in the device tree. The orientation of the
* panel is expressed as a property name "rotation" in the device tree. The
* rotation in the device tree is counter clockwise.
*
* Return: 0 when a valid rotation value (0, 90, 180, or 270) is read or the
* rotation property doesn't exist. Return a negative error code on failure.
*/
int of_drm_get_panel_orientation(const struct device_node *np,
enum drm_panel_orientation *orientation)
{
int rotation, ret;
ret = of_property_read_u32(np, "rotation", &rotation);
if (ret == -EINVAL) {
/* Don't return an error if there's no rotation property. */
*orientation = DRM_MODE_PANEL_ORIENTATION_UNKNOWN;
return 0;
}
if (ret < 0)
return ret;
if (rotation == 0)
*orientation = DRM_MODE_PANEL_ORIENTATION_NORMAL;
else if (rotation == 90)
*orientation = DRM_MODE_PANEL_ORIENTATION_RIGHT_UP;
else if (rotation == 180)
*orientation = DRM_MODE_PANEL_ORIENTATION_BOTTOM_UP;
else if (rotation == 270)
*orientation = DRM_MODE_PANEL_ORIENTATION_LEFT_UP;
else
return -EINVAL;
return 0;
}
EXPORT_SYMBOL(of_drm_get_panel_orientation);
#endif
/**
* drm_is_panel_follower() - Check if the device is a panel follower
* @dev: The 'struct device' to check
*
* This checks to see if a device needs to be power sequenced together with
* a panel using the panel follower API.
* At the moment panels can only be followed on device tree enabled systems.
* The "panel" property of the follower points to the panel to be followed.
*
* Return: true if we should be power sequenced with a panel; false otherwise.
*/
bool drm_is_panel_follower(struct device *dev)
{
/*
* The "panel" property is actually a phandle, but for simplicity we
* don't bother trying to parse it here. We just need to know if the
* property is there.
*/
return of_property_read_bool(dev->of_node, "panel");
}
EXPORT_SYMBOL(drm_is_panel_follower);
/**
* drm_panel_add_follower() - Register something to follow panel state.
* @follower_dev: The 'struct device' for the follower.
* @follower: The panel follower descriptor for the follower.
*
* A panel follower is called right after preparing the panel and right before
* unpreparing the panel. It's primary intention is to power on an associated
* touchscreen, though it could be used for any similar devices. Multiple
* devices are allowed the follow the same panel.
*
* If a follower is added to a panel that's already been turned on, the
* follower's prepare callback is called right away.
*
* At the moment panels can only be followed on device tree enabled systems.
* The "panel" property of the follower points to the panel to be followed.
*
* Return: 0 or an error code. Note that -ENODEV means that we detected that
* follower_dev is not actually following a panel. The caller may
* choose to ignore this return value if following a panel is optional.
*/
int drm_panel_add_follower(struct device *follower_dev,
struct drm_panel_follower *follower)
{
struct device_node *panel_np;
struct drm_panel *panel;
int ret;
panel_np = of_parse_phandle(follower_dev->of_node, "panel", 0);
if (!panel_np)
return -ENODEV;
panel = of_drm_find_panel(panel_np);
of_node_put(panel_np);
if (IS_ERR(panel))
return PTR_ERR(panel);
get_device(panel->dev);
follower->panel = panel;
mutex_lock(&panel->follower_lock);
list_add_tail(&follower->list, &panel->followers);
if (panel->prepared) {
ret = follower->funcs->panel_prepared(follower);
if (ret < 0)
dev_info(panel->dev, "%ps failed: %d\n",
follower->funcs->panel_prepared, ret);
}
mutex_unlock(&panel->follower_lock);
return 0;
}
EXPORT_SYMBOL(drm_panel_add_follower);
/**
* drm_panel_remove_follower() - Reverse drm_panel_add_follower().
* @follower: The panel follower descriptor for the follower.
*
* Undo drm_panel_add_follower(). This includes calling the follower's
* unprepare function if we're removed from a panel that's currently prepared.
*
* Return: 0 or an error code.
*/
void drm_panel_remove_follower(struct drm_panel_follower *follower)
{
struct drm_panel *panel = follower->panel;
int ret;
mutex_lock(&panel->follower_lock);
if (panel->prepared) {
ret = follower->funcs->panel_unpreparing(follower);
if (ret < 0)
dev_info(panel->dev, "%ps failed: %d\n",
follower->funcs->panel_unpreparing, ret);
}
list_del_init(&follower->list);
mutex_unlock(&panel->follower_lock);
put_device(panel->dev);
}
EXPORT_SYMBOL(drm_panel_remove_follower);
static void drm_panel_remove_follower_void(void *follower)
{
drm_panel_remove_follower(follower);
}
/**
* devm_drm_panel_add_follower() - devm version of drm_panel_add_follower()
* @follower_dev: The 'struct device' for the follower.
* @follower: The panel follower descriptor for the follower.
*
* Handles calling drm_panel_remove_follower() using devm on the follower_dev.
*
* Return: 0 or an error code.
*/
int devm_drm_panel_add_follower(struct device *follower_dev,
struct drm_panel_follower *follower)
{
int ret;
ret = drm_panel_add_follower(follower_dev, follower);
if (ret)
return ret;
return devm_add_action_or_reset(follower_dev,
drm_panel_remove_follower_void, follower);
}
EXPORT_SYMBOL(devm_drm_panel_add_follower);
#if IS_REACHABLE(CONFIG_BACKLIGHT_CLASS_DEVICE)
/**
* drm_panel_of_backlight - use backlight device node for backlight
* @panel: DRM panel
*
* Use this function to enable backlight handling if your panel
* uses device tree and has a backlight phandle.
*
* When the panel is enabled backlight will be enabled after a
* successful call to &drm_panel_funcs.enable()
*
* When the panel is disabled backlight will be disabled before the
* call to &drm_panel_funcs.disable().
*
* A typical implementation for a panel driver supporting device tree
* will call this function at probe time. Backlight will then be handled
* transparently without requiring any intervention from the driver.
* drm_panel_of_backlight() must be called after the call to drm_panel_init().
*
* Return: 0 on success or a negative error code on failure.
*/
int drm_panel_of_backlight(struct drm_panel *panel)
{
struct backlight_device *backlight;
if (!panel || !panel->dev)
return -EINVAL;
backlight = devm_of_find_backlight(panel->dev);
if (IS_ERR(backlight))
return PTR_ERR(backlight);
panel->backlight = backlight;
return 0;
}
EXPORT_SYMBOL(drm_panel_of_backlight);
#endif
MODULE_AUTHOR("Thierry Reding <treding@nvidia.com>");
MODULE_DESCRIPTION("DRM panel infrastructure");
MODULE_LICENSE("GPL and additional rights");