From 152dbdeab1b2571c107357a7bd59f5cd5be52e30 Mon Sep 17 00:00:00 2001 From: Sam Ravnborg Date: Sat, 7 Dec 2019 15:03:30 +0100 Subject: drm/panel: add backlight support Panels often support backlight as specified in a device tree. Update the drm_panel infrastructure to support this to simplify the drivers. With this the panel driver just needs to add the following to the probe() function: err = drm_panel_of_backlight(panel); if (err) return err; Then drm_panel will handle all the rest. There is one caveat with the backlight support. If drm_panel_(enable|disable) are called multiple times in a row then backlight_(enable|disable) will be called multiple times. The above will happen when a panel drivers unconditionally calls drm_panel_disable() in their shutdown() function, whan the panel is already disabled and then shutdown() is called. Reading the backlight code it seems safe to call the backlight_(enable|disable) several times. v3: - Improve comments, fix grammar (Laurent) - Do not fail in drm_panel_of_backlight() if no DT support (Laurent) - Log if backlight_(enable|disable) fails (Laurent) - Improve drm_panel_of_backlight() docs - Updated changelog with backlight analysis (triggered by Laurent) v2: - Drop test of CONFIG_DRM_PANEL in header-file (Laurent) - do not enable backlight if ->enable() returns an error Signed-off-by: Sam Ravnborg Reviewed-by: Laurent Pinchart Cc: Thierry Reding Cc: Laurent Pinchart Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Sean Paul Cc: David Airlie Cc: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20191207140353.23967-3-sam@ravnborg.org --- include/drm/drm_panel.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) (limited to 'include/drm/drm_panel.h') diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h index 2bd1d806dbeb..54b5576ce0a9 100644 --- a/include/drm/drm_panel.h +++ b/include/drm/drm_panel.h @@ -28,6 +28,7 @@ #include #include +struct backlight_device; struct device_node; struct drm_connector; struct drm_device; @@ -59,6 +60,10 @@ struct display_timing; * * To save power when no video data is transmitted, a driver can power down * the panel. This is the job of the .unprepare() function. + * + * Backlight can be handled automatically if configured using + * drm_panel_of_backlight(). Then the driver does not need to implement the + * functionality to enable/disable backlight. */ struct drm_panel_funcs { /** @@ -144,6 +149,17 @@ struct drm_panel { */ struct device *dev; + /** + * @backlight: + * + * Backlight device, used to turn on backlight after the call + * to enable(), and to turn off backlight before the call to + * disable(). + * backlight is set by drm_panel_of_backlight() and drivers + * shall not assign it. + */ + struct backlight_device *backlight; + /** * @funcs: * @@ -195,4 +211,13 @@ static inline struct drm_panel *of_drm_find_panel(const struct device_node *np) } #endif +#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE) +int drm_panel_of_backlight(struct drm_panel *panel); +#else +static inline int drm_panel_of_backlight(struct drm_panel *panel) +{ + return 0; +} +#endif + #endif -- cgit v1.2.3