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author | Sam Ravnborg <sam@ravnborg.org> | 2019-12-07 15:03:30 +0100 |
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committer | Sam Ravnborg <sam@ravnborg.org> | 2019-12-09 22:57:26 +0100 |
commit | 152dbdeab1b2571c107357a7bd59f5cd5be52e30 (patch) | |
tree | c928343816c2ef2eeff3acf351331a56d1e1350d /include | |
parent | 5dce87a91970bf7c7ef3de5e2bff08b695d858a3 (diff) | |
download | linux-stable-152dbdeab1b2571c107357a7bd59f5cd5be52e30.tar.gz linux-stable-152dbdeab1b2571c107357a7bd59f5cd5be52e30.tar.bz2 linux-stable-152dbdeab1b2571c107357a7bd59f5cd5be52e30.zip |
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 <sam@ravnborg.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <maxime.ripard@bootlin.com>
Cc: Sean Paul <sean@poorly.run>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20191207140353.23967-3-sam@ravnborg.org
Diffstat (limited to 'include')
-rw-r--r-- | include/drm/drm_panel.h | 25 |
1 files changed, 25 insertions, 0 deletions
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 <linux/errno.h> #include <linux/list.h> +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 { /** @@ -145,6 +150,17 @@ 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: * * Operations that can be performed on the panel. @@ -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 |