| Message ID | 20191207140353.23967-3-sam@ravnborg.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | drm/panel infrastructure + backlight update | expand |
Hi Sam, Thank you for the patch. On Sat, Dec 07, 2019 at 03:03:30PM +0100, Sam Ravnborg wrote: > Panels often supports backlight as specified in a device tree. s/supports/support/ > 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 row then backlight_(enable|disable) will be called multiple times. s/in row/in a row/ > 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> > 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> > --- > drivers/gpu/drm/drm_panel.c | 58 ++++++++++++++++++++++++++++++++++++- > include/drm/drm_panel.h | 25 ++++++++++++++++ > 2 files changed, 82 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c > index 4ab7229fb22b..c312d5eb214d 100644 > --- a/drivers/gpu/drm/drm_panel.c > +++ b/drivers/gpu/drm/drm_panel.c > @@ -21,11 +21,13 @@ > * 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); > @@ -196,11 +198,20 @@ EXPORT_SYMBOL(drm_panel_unprepare); > */ > int drm_panel_enable(struct drm_panel *panel) > { > + int ret = 0; > + > if (!panel) > return -EINVAL; > > if (panel->funcs && panel->funcs->enable) > - return panel->funcs->enable(panel); > + ret = panel->funcs->enable(panel); > + > + if (ret < 0) > + return ret; You can move this within the above if () block and avoid initializing ret to 0: if (panel->funcs && panel->funcs->enable) { ret = panel->funcs->enable(panel); if (ret < 0) return ret; } With these small issues addressed, Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> > + ret = backlight_enable(panel->backlight); > + if (ret < 0) > + DRM_DEV_INFO(panel->dev, "failed to enable backlight: %d\n", ret); > > return 0; > } > @@ -218,9 +229,15 @@ EXPORT_SYMBOL(drm_panel_enable); > */ > int drm_panel_disable(struct drm_panel *panel) > { > + int ret; > + > if (!panel) > return -EINVAL; > > + 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) > return panel->funcs->disable(panel); > > @@ -289,6 +306,45 @@ struct drm_panel *of_drm_find_panel(const struct device_node *np) > EXPORT_SYMBOL(of_drm_find_panel); > #endif > > +#ifdef 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 > + * successfull 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"); > diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h > index d71655b2634c..c751c9b17df0 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 { > /** > @@ -146,6 +151,17 @@ 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: > * > @@ -197,4 +213,13 @@ 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
On Sat, Dec 7, 2019 at 3:04 PM Sam Ravnborg <sam@ravnborg.org> wrote: > Panels often supports 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 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: v3 looks good to me +/- Laurent's comments: Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Yours, Linus Walleij
diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c index 4ab7229fb22b..c312d5eb214d 100644 --- a/drivers/gpu/drm/drm_panel.c +++ b/drivers/gpu/drm/drm_panel.c @@ -21,11 +21,13 @@ * 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); @@ -196,11 +198,20 @@ EXPORT_SYMBOL(drm_panel_unprepare); */ int drm_panel_enable(struct drm_panel *panel) { + int ret = 0; + if (!panel) return -EINVAL; if (panel->funcs && panel->funcs->enable) - return panel->funcs->enable(panel); + ret = panel->funcs->enable(panel); + + if (ret < 0) + return ret; + + ret = backlight_enable(panel->backlight); + if (ret < 0) + DRM_DEV_INFO(panel->dev, "failed to enable backlight: %d\n", ret); return 0; } @@ -218,9 +229,15 @@ EXPORT_SYMBOL(drm_panel_enable); */ int drm_panel_disable(struct drm_panel *panel) { + int ret; + if (!panel) return -EINVAL; + 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) return panel->funcs->disable(panel); @@ -289,6 +306,45 @@ struct drm_panel *of_drm_find_panel(const struct device_node *np) EXPORT_SYMBOL(of_drm_find_panel); #endif +#ifdef 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 + * successfull 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"); diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h index d71655b2634c..c751c9b17df0 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 { /** @@ -146,6 +151,17 @@ 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: * @@ -197,4 +213,13 @@ 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
Panels often supports 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 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> 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> --- drivers/gpu/drm/drm_panel.c | 58 ++++++++++++++++++++++++++++++++++++- include/drm/drm_panel.h | 25 ++++++++++++++++ 2 files changed, 82 insertions(+), 1 deletion(-)