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From: Sam Ravnborg <sam@ravnborg.org>
To: dri-devel@lists.freedesktop.org,
	Thierry Reding <thierry.reding@gmail.com>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Linus Walleij <linus.walleij@linaro.org>,
	Sam Ravnborg <sam@ravnborg.org>
Cc: Neil Armstrong <narmstrong@baylibre.com>,
	David Airlie <airlied@linux.ie>,
	Maxime Ripard <maxime.ripard@bootlin.com>,
	linux-samsung-soc@vger.kernel.org,
	linux-rockchip@lists.infradead.org,
	Tomi Valkeinen <tomi.valkeinen@ti.com>,
	Jagan Teki <jagan@amarulasolutions.com>,
	NXP Linux Team <linux-imx@nxp.com>,
	Jitao Shi <jitao.shi@mediatek.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	linux-mediatek@lists.infradead.org,
	Abhinav Kumar <abhinavk@codeaurora.org>,
	linux-tegra@vger.kernel.org, Sean Paul <sean@poorly.run>,
	linux-arm-kernel@lists.infradead.org,
	Purism Kernel Team <kernel@puri.sm>,
	linux-renesas-soc@vger.kernel.org,
	Boris Brezillon <boris.brezillon@collabora.com>
Subject: [PATCH v2 02/25] drm/panel: add backlight support
Date: Sat,  7 Dec 2019 15:03:30 +0100	[thread overview]
Message-ID: <20191207140353.23967-3-sam@ravnborg.org> (raw)
In-Reply-To: <20191207140353.23967-1-sam@ravnborg.org>

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(-)

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
-- 
2.20.1

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

WARNING: multiple messages have this Message-ID
From: Sam Ravnborg <sam@ravnborg.org>
To: dri-devel@lists.freedesktop.org,
	Thierry Reding <thierry.reding@gmail.com>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Linus Walleij <linus.walleij@linaro.org>,
	Sam Ravnborg <sam@ravnborg.org>
Cc: Abhinav Kumar <abhinavk@codeaurora.org>,
	Andrzej Hajda <a.hajda@samsung.com>,
	Benjamin Gaignard <benjamin.gaignard@linaro.org>,
	Boris Brezillon <boris.brezillon@collabora.com>,
	Daniel Vetter <daniel@ffwll.ch>, David Airlie <airlied@linux.ie>,
	Jagan Teki <jagan@amarulasolutions.com>,
	Jitao Shi <jitao.shi@mediatek.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org,
	linux-renesas-soc@vger.kernel.org,
	linux-rockchip@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org, linux-tegra@vger.kernel.org,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Neil Armstrong <narmstrong@baylibre.com>,
	NXP Linux Team <linux-imx@nxp.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Purism Kernel Team <kernel@puri.sm>, Sean Paul <sean@poorly.run>,
	Stefan Agner <stefan@agner.ch>,
	Tomi Valkeinen <tomi.valkeinen@ti.com>,
	Maxime Ripard <maxime.ripard@bootlin.com>
Subject: [PATCH v2 02/25] drm/panel: add backlight support
Date: Sat,  7 Dec 2019 15:03:30 +0100	[thread overview]
Message-ID: <20191207140353.23967-3-sam@ravnborg.org> (raw)
In-Reply-To: <20191207140353.23967-1-sam@ravnborg.org>

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(-)

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
-- 
2.20.1


WARNING: multiple messages have this Message-ID
From: Sam Ravnborg <sam@ravnborg.org>
To: dri-devel@lists.freedesktop.org,
	Thierry Reding <thierry.reding@gmail.com>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Linus Walleij <linus.walleij@linaro.org>,
	Sam Ravnborg <sam@ravnborg.org>
Cc: Neil Armstrong <narmstrong@baylibre.com>,
	David Airlie <airlied@linux.ie>, Stefan Agner <stefan@agner.ch>,
	Andrzej Hajda <a.hajda@samsung.com>,
	Benjamin Gaignard <benjamin.gaignard@linaro.org>,
	Maxime Ripard <maxime.ripard@bootlin.com>,
	linux-samsung-soc@vger.kernel.org,
	linux-rockchip@lists.infradead.org,
	Tomi Valkeinen <tomi.valkeinen@ti.com>,
	Jagan Teki <jagan@amarulasolutions.com>,
	NXP Linux Team <linux-imx@nxp.com>,
	Jitao Shi <jitao.shi@mediatek.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	linux-mediatek@lists.infradead.org,
	Abhinav Kumar <abhinavk@codeaurora.org>,
	linux-tegra@vger.kernel.org, Sean Paul <sean@poorly.run>,
	linux-arm-kernel@lists.infradead.org,
	Purism Kernel Team <kernel@puri.sm>,
	linux-renesas-soc@vger.kernel.org,
	Boris Brezillon <boris.brezillon@collabora.com>,
	Daniel Vetter <daniel@ffwll.ch>
Subject: [PATCH v2 02/25] drm/panel: add backlight support
Date: Sat,  7 Dec 2019 15:03:30 +0100	[thread overview]
Message-ID: <20191207140353.23967-3-sam@ravnborg.org> (raw)
In-Reply-To: <20191207140353.23967-1-sam@ravnborg.org>

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(-)

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
-- 
2.20.1


_______________________________________________
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WARNING: multiple messages have this Message-ID
From: Sam Ravnborg <sam@ravnborg.org>
To: dri-devel@lists.freedesktop.org,
	Thierry Reding <thierry.reding@gmail.com>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Linus Walleij <linus.walleij@linaro.org>,
	Sam Ravnborg <sam@ravnborg.org>
Cc: Neil Armstrong <narmstrong@baylibre.com>,
	David Airlie <airlied@linux.ie>, Stefan Agner <stefan@agner.ch>,
	Andrzej Hajda <a.hajda@samsung.com>,
	Benjamin Gaignard <benjamin.gaignard@linaro.org>,
	Maxime Ripard <maxime.ripard@bootlin.com>,
	linux-samsung-soc@vger.kernel.org,
	linux-rockchip@lists.infradead.org,
	Tomi Valkeinen <tomi.valkeinen@ti.com>,
	Jagan Teki <jagan@amarulasolutions.com>,
	NXP Linux Team <linux-imx@nxp.com>,
	Jitao Shi <jitao.shi@mediatek.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	linux-mediatek@lists.infradead.org,
	Abhinav Kumar <abhinavk@codeaurora.org>,
	linux-tegra@vger.kernel.org, Sean Paul <sean@poorly.run>,
	linux-arm-kernel@lists.infradead.org,
	Purism Kernel Team <kernel@puri.sm>,
	linux-renesas-soc@vger.kernel.org,
	Boris Brezillon <boris.brezillon@collabora.com>,
	Daniel Vetter <daniel@ffwll.ch>
Subject: [PATCH v2 02/25] drm/panel: add backlight support
Date: Sat,  7 Dec 2019 15:03:30 +0100	[thread overview]
Message-ID: <20191207140353.23967-3-sam@ravnborg.org> (raw)
In-Reply-To: <20191207140353.23967-1-sam@ravnborg.org>

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(-)

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
-- 
2.20.1


_______________________________________________
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2019-12-07 14:03 UTC|newest]

Thread overview: 128+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-07 14:03 [PATCH v2 0/25] drm/panel infrastructure + backlight update Sam Ravnborg
2019-12-07 14:03 ` Sam Ravnborg
2019-12-07 14:03 ` Sam Ravnborg
2019-12-07 14:03 ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 01/25] drm/drm_panel: no error when no callback Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 19:08   ` Michał Mirosław
2019-12-08  8:41     ` Sam Ravnborg
2019-12-09  0:50   ` Laurent Pinchart
2019-12-09  0:50     ` Laurent Pinchart
2019-12-09  0:50     ` Laurent Pinchart
2019-12-09  0:50     ` Laurent Pinchart
2019-12-07 14:03 ` Sam Ravnborg [this message]
2019-12-07 14:03   ` [PATCH v2 02/25] drm/panel: add backlight support Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-09  0:55   ` Laurent Pinchart
2019-12-09  0:55     ` Laurent Pinchart
2019-12-09  0:55     ` Laurent Pinchart
2019-12-09  0:55     ` Laurent Pinchart
2019-12-13 13:30   ` Linus Walleij
2019-12-13 13:30     ` Linus Walleij
2019-12-13 13:30     ` Linus Walleij
2019-12-13 13:30     ` Linus Walleij
2019-12-13 13:30     ` Linus Walleij
2019-12-07 14:03 ` [PATCH v2 03/25] drm/panel: simple: use drm_panel " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 04/25] drm: get drm_bridge_panel connector via helper Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-10 14:48   ` [PATCH] drm/bridge: panel: export drm_panel_bridge_connector Mihail Atanassov
2019-12-10 14:48     ` Mihail Atanassov
2019-12-10 16:26     ` Laurent Pinchart
2019-12-10 16:26       ` Laurent Pinchart
2019-12-10 17:28       ` Mihail Atanassov
2019-12-10 17:28         ` Mihail Atanassov
2019-12-07 14:03 ` [PATCH v2 05/25] drm/panel: add drm_connector argument to get_modes() Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 06/25] drm/panel: decouple connector from drm_panel Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 07/25] drm/panel: drop drm_device " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 08/25] drm/panel: feiyang-fy07024di26a30d: use drm_panel backlight support Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 09/25] drm/panel: ilitek-ili9881c: " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 10/25] drm/panel: innolux-p079zca: " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 11/25] drm/panel: kingdisplay-kd097d04: " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 12/25] drm/panel: lvds: " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 13/25] drm/panel: olimex-lcd-olinuxino: " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 14/25] drm/panel: osd-osd101t2587-53ts: " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 15/25] drm/panel: panasonic-vvx10f034n00: " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 16/25] drm/panel: raydium-rm68200: " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 17/25] drm/panel: rocktech-jh057n00900: " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 18/25] drm/panel: ronbo-rb070d30: " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 19/25] drm/panel: seiko-43wvf1g: " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 20/25] drm/panel: sharp-lq101r1sx01: " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 21/25] drm/panel: sharp-ls043t1le01: " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 22/25] drm/panel: sitronix-st7701: " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 23/25] drm/panel: sitronix-st7789v: " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 24/25] drm/panel: tpo-td028ttec1: " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03 ` [PATCH v2 25/25] drm/panel: tpo-tpg110: " Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-07 14:03   ` Sam Ravnborg
2019-12-09 22:04 ` [PATCH v2 0/25] drm/panel infrastructure + backlight update Sam Ravnborg
2019-12-09 22:04   ` Sam Ravnborg
2019-12-09 22:04   ` Sam Ravnborg
2019-12-09 22:04   ` Sam Ravnborg

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