drm/panel: Allow powering on panel follower after panel is enabled

Some touch controllers have to be powered on after the panel's backlight
is enabled. To support these controllers, introduce .panel_enabled() and
.panel_disabling() to panel_follower_funcs and use them to power on the
device after the panel and its backlight are enabled.

Signed-off-by: Pin-yen Lin <treapking@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20250818115015.2909525-1-treapking@chromium.org
This commit is contained in:
Pin-yen Lin 2025-08-18 19:49:33 +08:00 committed by Douglas Anderson
parent efe927b970
commit 2eb22214c1
2 changed files with 76 additions and 11 deletions

View File

@ -134,6 +134,9 @@ void drm_panel_prepare(struct drm_panel *panel)
panel->prepared = true;
list_for_each_entry(follower, &panel->followers, list) {
if (!follower->funcs->panel_prepared)
continue;
ret = follower->funcs->panel_prepared(follower);
if (ret < 0)
dev_info(panel->dev, "%ps failed: %d\n",
@ -179,6 +182,9 @@ void drm_panel_unprepare(struct drm_panel *panel)
mutex_lock(&panel->follower_lock);
list_for_each_entry(follower, &panel->followers, list) {
if (!follower->funcs->panel_unpreparing)
continue;
ret = follower->funcs->panel_unpreparing(follower);
if (ret < 0)
dev_info(panel->dev, "%ps failed: %d\n",
@ -209,6 +215,7 @@ EXPORT_SYMBOL(drm_panel_unprepare);
*/
void drm_panel_enable(struct drm_panel *panel)
{
struct drm_panel_follower *follower;
int ret;
if (!panel)
@ -219,10 +226,12 @@ void drm_panel_enable(struct drm_panel *panel)
return;
}
mutex_lock(&panel->follower_lock);
if (panel->funcs && panel->funcs->enable) {
ret = panel->funcs->enable(panel);
if (ret < 0)
return;
goto exit;
}
panel->enabled = true;
@ -230,6 +239,19 @@ void drm_panel_enable(struct drm_panel *panel)
if (ret < 0)
DRM_DEV_INFO(panel->dev, "failed to enable backlight: %d\n",
ret);
list_for_each_entry(follower, &panel->followers, list) {
if (!follower->funcs->panel_enabled)
continue;
ret = follower->funcs->panel_enabled(follower);
if (ret < 0)
dev_info(panel->dev, "%ps failed: %d\n",
follower->funcs->panel_enabled, ret);
}
exit:
mutex_unlock(&panel->follower_lock);
}
EXPORT_SYMBOL(drm_panel_enable);
@ -243,6 +265,7 @@ EXPORT_SYMBOL(drm_panel_enable);
*/
void drm_panel_disable(struct drm_panel *panel)
{
struct drm_panel_follower *follower;
int ret;
if (!panel)
@ -262,6 +285,18 @@ void drm_panel_disable(struct drm_panel *panel)
return;
}
mutex_lock(&panel->follower_lock);
list_for_each_entry(follower, &panel->followers, list) {
if (!follower->funcs->panel_disabling)
continue;
ret = follower->funcs->panel_disabling(follower);
if (ret < 0)
dev_info(panel->dev, "%ps failed: %d\n",
follower->funcs->panel_disabling, ret);
}
ret = backlight_disable(panel->backlight);
if (ret < 0)
DRM_DEV_INFO(panel->dev, "failed to disable backlight: %d\n",
@ -270,9 +305,12 @@ void drm_panel_disable(struct drm_panel *panel)
if (panel->funcs && panel->funcs->disable) {
ret = panel->funcs->disable(panel);
if (ret < 0)
return;
goto exit;
}
panel->enabled = false;
exit:
mutex_unlock(&panel->follower_lock);
}
EXPORT_SYMBOL(drm_panel_disable);
@ -539,13 +577,13 @@ EXPORT_SYMBOL(drm_is_panel_follower);
* @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.
* A panel follower is called right after preparing/enabling the panel and right
* before unpreparing/disabling 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.
* If a follower is added to a panel that's already been prepared/enabled, the
* follower's prepared/enabled callback is called right away.
*
* The "panel" property of the follower points to the panel to be followed.
*
@ -569,12 +607,18 @@ int drm_panel_add_follower(struct device *follower_dev,
mutex_lock(&panel->follower_lock);
list_add_tail(&follower->list, &panel->followers);
if (panel->prepared) {
if (panel->prepared && follower->funcs->panel_prepared) {
ret = follower->funcs->panel_prepared(follower);
if (ret < 0)
dev_info(panel->dev, "%ps failed: %d\n",
follower->funcs->panel_prepared, ret);
}
if (panel->enabled && follower->funcs->panel_enabled) {
ret = follower->funcs->panel_enabled(follower);
if (ret < 0)
dev_info(panel->dev, "%ps failed: %d\n",
follower->funcs->panel_enabled, ret);
}
mutex_unlock(&panel->follower_lock);
@ -587,7 +631,8 @@ EXPORT_SYMBOL(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.
* unpreparing/disabling function if we're removed from a panel that's currently
* prepared/enabled.
*
* Return: 0 or an error code.
*/
@ -598,7 +643,13 @@ void drm_panel_remove_follower(struct drm_panel_follower *follower)
mutex_lock(&panel->follower_lock);
if (panel->prepared) {
if (panel->enabled && follower->funcs->panel_disabling) {
ret = follower->funcs->panel_disabling(follower);
if (ret < 0)
dev_info(panel->dev, "%ps failed: %d\n",
follower->funcs->panel_disabling, ret);
}
if (panel->prepared && follower->funcs->panel_unpreparing) {
ret = follower->funcs->panel_unpreparing(follower);
if (ret < 0)
dev_info(panel->dev, "%ps failed: %d\n",

View File

@ -160,6 +160,20 @@ struct drm_panel_follower_funcs {
* Called before the panel is powered off.
*/
int (*panel_unpreparing)(struct drm_panel_follower *follower);
/**
* @panel_enabled:
*
* Called after the panel and the backlight have been enabled.
*/
int (*panel_enabled)(struct drm_panel_follower *follower);
/**
* @panel_disabling:
*
* Called before the panel and the backlight are disabled.
*/
int (*panel_disabling)(struct drm_panel_follower *follower);
};
struct drm_panel_follower {