[PATCH v17 00/10] Add backlight helper functions

[PATCH v17 00/10] Add backlight helper functions

[Meghana Madhyastha]

Move drm helper functions from tinydrm-helpers to linux/backlight for
ease of use by callers in other drivers.

changes in v17:
-set fb_blank along with clearing the BL_CORE_FBBLANK bit 
-rebase with drm-misc-next
-fix checkpath errors/warnings
-Make the gpio_backlight issue appear as a comment in the
 code and not as part of the docs
-rebase with drm-misc-next
-convert st7735r callers from tinydrm specific helpers
 to new generic backlight helpers
-remove select BACKLIGHT_LCD_SUPPORT and select 
 BACKLIGHT_CLASS_DEVICE from tinydrm/Kconfig
-fix checkpath errors/warnings
-rename devm_backlight_put to 
 devm_backlight_release
-remove redundant NULL check
-remove put_device() to avoid double put 
 as we are using the devm version

Meghana Madhyastha (10):
  video: backlight: Add helpers to enable and disable backlight
  drm/tinydrm: Convert tinydrm_enable/disable_backlight to
    backlight_enable/disable
  video: backlight: Add of_find_backlight helper in backlight.c
  drm/tinydrm: Replace tinydrm_of_find_backlight with of_find_backlight
  video: backlight: Add devres versions of of_find_backlight
  drm/tinydrm: Call devres version of of_find_backlight
  drm/panel: Use backlight_enable/disable helpers
  drm/omapdrm: Use backlight_enable/disable helpers
  drm/panel: Use of_find_backlight helper
  drm/omapdrm: Use of_find_backlight helper

 drivers/gpu/drm/omapdrm/displays/panel-dpi.c    | 32 ++-------
 drivers/gpu/drm/panel/panel-innolux-p079zca.c   | 29 ++------
 drivers/gpu/drm/panel/panel-jdi-lt070me05000.c  |  6 +-
 drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c | 35 ++-------
 drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c | 35 ++-------
 drivers/gpu/drm/tinydrm/Kconfig                 |  2 -
 drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c  | 95 -------------------------
 drivers/gpu/drm/tinydrm/mi0283qt.c              |  3 +-
 drivers/gpu/drm/tinydrm/mipi-dbi.c              |  4 +-
 drivers/gpu/drm/tinydrm/st7735r.c               |  3 +-
 drivers/video/backlight/backlight.c             | 73 +++++++++++++++++++
 include/drm/tinydrm/tinydrm-helpers.h           |  4 --
 include/linux/backlight.h                       | 58 +++++++++++++++
 13 files changed, 164 insertions(+), 215 deletions(-)

-- 
2.11.0

[PATCH v17 01/10] video: backlight: Add helpers to enable and disable backlight

[Meghana Madhyastha]

Add helper functions backlight_enable and backlight_disable to
enable/disable a backlight device. These helper functions can
then be used by different drm and tinydrm drivers to avoid
repetition of code and also to enforce a uniform and consistent
way to enable/disable a backlight device.

Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
---
changes in v17:
-set fb_blank along with clearing the BL_CORE_FBBLANK bit

 include/linux/backlight.h | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index af7003548..ace825e2c 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -130,6 +130,38 @@ static inline int backlight_update_status(struct backlight_device *bd)
 	return ret;
 }
 
+/**
+ * backlight_enable - Enable backlight
+ * @bd: the backlight device to enable
+ */
+static inline int backlight_enable(struct backlight_device *bd)
+{
+	if (!bd)
+		return 0;
+
+	bd->props.power = FB_BLANK_UNBLANK;
+	bd->props.fb_blank = FB_BLANK_UNBLANK;
+	bd->props.state &= ~BL_CORE_FBBLANK;
+
+	return backlight_update_status(bd);
+}
+
+/**
+ * backlight_disable - Disable backlight
+ * @bd: the backlight device to disable
+ */
+static inline int backlight_disable(struct backlight_device *bd)
+{
+	if (!bd)
+		return 0;
+
+	bd->props.power = FB_BLANK_POWERDOWN;
+	bd->props.fb_blank = FB_BLANK_POWERDOWN;
+	bd->props.state |= BL_CORE_FBBLANK;
+
+	return backlight_update_status(bd);
+}
+
 extern struct backlight_device *backlight_device_register(const char *name,
 	struct device *dev, void *devdata, const struct backlight_ops *ops,
 	const struct backlight_properties *props);
-- 
2.11.0

[PATCH v17 02/10] drm/tinydrm: Convert tinydrm_enable/disable_backlight to backlight_enable/disable

[Meghana Madhyastha]

Remove tinydrm_enable/disable_backlight and let the callers call the
more generic backlight_enable/disable helpers

Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
---
changes in v17:
-rebase with drm-misc-next

 drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 55 --------------------------
 drivers/gpu/drm/tinydrm/mipi-dbi.c             |  4 +-
 include/drm/tinydrm/tinydrm-helpers.h          |  2 -
 3 files changed, 2 insertions(+), 59 deletions(-)

diff --git a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
index bf96072d1..7326e1758 100644
--- a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
+++ b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
@@ -276,61 +276,6 @@ struct backlight_device *tinydrm_of_find_backlight(struct device *dev)
 }
 EXPORT_SYMBOL(tinydrm_of_find_backlight);
 
-/**
- * tinydrm_enable_backlight - Enable backlight helper
- * @backlight: Backlight device
- *
- * Returns:
- * Zero on success, negative error code on failure.
- */
-int tinydrm_enable_backlight(struct backlight_device *backlight)
-{
-	unsigned int old_state;
-	int ret;
-
-	if (!backlight)
-		return 0;
-
-	old_state = backlight->props.state;
-	backlight->props.state &= ~BL_CORE_FBBLANK;
-	DRM_DEBUG_KMS("Backlight state: 0x%x -> 0x%x\n", old_state,
-		      backlight->props.state);
-
-	ret = backlight_update_status(backlight);
-	if (ret)
-		DRM_ERROR("Failed to enable backlight %d\n", ret);
-
-	return ret;
-}
-EXPORT_SYMBOL(tinydrm_enable_backlight);
-
-/**
- * tinydrm_disable_backlight - Disable backlight helper
- * @backlight: Backlight device
- *
- * Returns:
- * Zero on success, negative error code on failure.
- */
-int tinydrm_disable_backlight(struct backlight_device *backlight)
-{
-	unsigned int old_state;
-	int ret;
-
-	if (!backlight)
-		return 0;
-
-	old_state = backlight->props.state;
-	backlight->props.state |= BL_CORE_FBBLANK;
-	DRM_DEBUG_KMS("Backlight state: 0x%x -> 0x%x\n", old_state,
-		      backlight->props.state);
-	ret = backlight_update_status(backlight);
-	if (ret)
-		DRM_ERROR("Failed to disable backlight %d\n", ret);
-
-	return ret;
-}
-EXPORT_SYMBOL(tinydrm_disable_backlight);
-
 #if IS_ENABLED(CONFIG_SPI)
 
 /**
diff --git a/drivers/gpu/drm/tinydrm/mipi-dbi.c b/drivers/gpu/drm/tinydrm/mipi-dbi.c
index 75dd65c57..9e903812b 100644
--- a/drivers/gpu/drm/tinydrm/mipi-dbi.c
+++ b/drivers/gpu/drm/tinydrm/mipi-dbi.c
@@ -286,7 +286,7 @@ void mipi_dbi_enable_flush(struct mipi_dbi *mipi)
 	if (fb)
 		fb->funcs->dirty(fb, NULL, 0, 0, NULL, 0);
 
-	tinydrm_enable_backlight(mipi->backlight);
+	backlight_enable(mipi->backlight);
 }
 EXPORT_SYMBOL(mipi_dbi_enable_flush);
 
@@ -325,7 +325,7 @@ void mipi_dbi_pipe_disable(struct drm_simple_display_pipe *pipe)
 	mipi->enabled = false;
 
 	if (mipi->backlight)
-		tinydrm_disable_backlight(mipi->backlight);
+		backlight_disable(mipi->backlight);
 	else
 		mipi_dbi_blank(mipi);
 
diff --git a/include/drm/tinydrm/tinydrm-helpers.h b/include/drm/tinydrm/tinydrm-helpers.h
index d554ded60..f54fae03e 100644
--- a/include/drm/tinydrm/tinydrm-helpers.h
+++ b/include/drm/tinydrm/tinydrm-helpers.h
@@ -47,8 +47,6 @@ void tinydrm_xrgb8888_to_gray8(u8 *dst, void *vaddr, struct drm_framebuffer *fb,
 			       struct drm_clip_rect *clip);
 
 struct backlight_device *tinydrm_of_find_backlight(struct device *dev);
-int tinydrm_enable_backlight(struct backlight_device *backlight);
-int tinydrm_disable_backlight(struct backlight_device *backlight);
 
 size_t tinydrm_spi_max_transfer_size(struct spi_device *spi, size_t max_len);
 bool tinydrm_spi_bpw_supported(struct spi_device *spi, u8 bpw);
-- 
2.11.0

[PATCH v17 03/10] video: backlight: Add of_find_backlight helper in backlight.c

[Meghana Madhyastha]

Add of_find_backlight, a helper function which is a generic version
of tinydrm_of_find_backlight that can be used by other drivers to avoid
repetition of code and simplify things.

Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
---
changes in v17:
-rebase with drm-misc-next
-convert st7735r callers from tinydrm specific helpers
 to new generic backlight helpers
-remove select BACKLIGHT_LCD_SUPPORT
 and select BACKLIGHT_CLASS_DEVICE from
 tinydrm/Kconfig

 drivers/video/backlight/backlight.c | 43 +++++++++++++++++++++++++++++++++++++
 include/linux/backlight.h           | 19 ++++++++++++++++
 2 files changed, 62 insertions(+)

diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index 8049e7656..553bf5c48 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -580,6 +580,49 @@ struct backlight_device *of_find_backlight_by_node(struct device_node *node)
 EXPORT_SYMBOL(of_find_backlight_by_node);
 #endif
 
+/**
+ * of_find_backlight - Get backlight device
+ * @dev: Device
+ *
+ * This function looks for a property named 'backlight' on the DT node
+ * connected to @dev and looks up the backlight device.
+ *
+ * Call backlight_put() to drop the reference on the backlight device.
+ *
+ * Returns:
+ * A pointer to the backlight device if found.
+ * Error pointer -EPROBE_DEFER if the DT property is set, but no backlight
+ * device is found.
+ * NULL if there's no backlight property.
+ */
+struct backlight_device *of_find_backlight(struct device *dev)
+{
+	struct backlight_device *bd = NULL;
+	struct device_node *np;
+
+	if (!dev)
+		return NULL;
+
+	if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
+		np = of_parse_phandle(dev->of_node, "backlight", 0);
+		if (np) {
+			bd = of_find_backlight_by_node(np);
+			of_node_put(np);
+			if (!bd)
+				return ERR_PTR(-EPROBE_DEFER);
+			/*
+			 * Note: gpio_backlight uses brightness as
+			 * power state during probe
+			 */
+			if (!bd->props.brightness)
+				bd->props.brightness = bd->props.max_brightness;
+		}
+	}
+
+	return bd;
+}
+EXPORT_SYMBOL(of_find_backlight);
+
 static void __exit backlight_class_exit(void)
 {
 	class_destroy(backlight_class);
diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index ace825e2c..ddc9bade4 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -162,6 +162,16 @@ static inline int backlight_disable(struct backlight_device *bd)
 	return backlight_update_status(bd);
 }
 
+/**
+ * backlight_put - Drop backlight reference
+ * @bd: the backlight device to put
+ */
+static inline void backlight_put(struct backlight_device *bd)
+{
+	if (bd)
+		put_device(&bd->dev);
+}
+
 extern struct backlight_device *backlight_device_register(const char *name,
 	struct device *dev, void *devdata, const struct backlight_ops *ops,
 	const struct backlight_properties *props);
@@ -205,4 +215,13 @@ of_find_backlight_by_node(struct device_node *node)
 }
 #endif
 
+#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
+struct backlight_device *of_find_backlight(struct device *dev);
+#else
+static inline struct backlight_device *of_find_backlight(struct device *dev)
+{
+	return NULL;
+}
+#endif
+
 #endif
-- 
2.11.0

[PATCH v17 04/10] drm/tinydrm: Replace tinydrm_of_find_backlight with of_find_backlight

[Meghana Madhyastha]

Remove tinydrm_of_find_backlight from tinydrm-helpers.c. We now have
a generic of_find_backlight defined in backlight.c. Let the callers
of tinydrm_of_find_backlight call of_find_backlight. Also, remove
select BACKLIGHT_LCD_SUPPORT and select BACKLIGHT_CLASS_DEVICE from
tinydrm/Kconfig as it is a hack that is no longer needed.

Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
---
changes in v17:
-rebase with drm-misc-next
-convert st7735r callers from tinydrm specific helpers
 to new generic backlight helpers
-remove select BACKLIGHT_LCD_SUPPORT
 and select BACKLIGHT_CLASS_DEVICE from
 tinydrm/Kconfig

 drivers/gpu/drm/tinydrm/Kconfig                |  2 --
 drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 40 --------------------------
 drivers/gpu/drm/tinydrm/mi0283qt.c             |  3 +-
 drivers/gpu/drm/tinydrm/st7735r.c              |  3 +-
 include/drm/tinydrm/tinydrm-helpers.h          |  2 --
 5 files changed, 4 insertions(+), 46 deletions(-)

diff --git a/drivers/gpu/drm/tinydrm/Kconfig b/drivers/gpu/drm/tinydrm/Kconfig
index b0e567d41..13339be84 100644
--- a/drivers/gpu/drm/tinydrm/Kconfig
+++ b/drivers/gpu/drm/tinydrm/Kconfig
@@ -3,8 +3,6 @@ menuconfig DRM_TINYDRM
 	depends on DRM
 	select DRM_KMS_HELPER
 	select DRM_KMS_CMA_HELPER
-	select BACKLIGHT_LCD_SUPPORT
-	select BACKLIGHT_CLASS_DEVICE
 	help
 	  Choose this option if you have a tinydrm supported display.
 	  If M is selected the module will be called tinydrm.
diff --git a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
index 7326e1758..d1c3ce9ab 100644
--- a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
+++ b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
@@ -236,46 +236,6 @@ void tinydrm_xrgb8888_to_gray8(u8 *dst, void *vaddr, struct drm_framebuffer *fb,
 }
 EXPORT_SYMBOL(tinydrm_xrgb8888_to_gray8);
 
-/**
- * tinydrm_of_find_backlight - Find backlight device in device-tree
- * @dev: Device
- *
- * This function looks for a DT node pointed to by a property named 'backlight'
- * and uses of_find_backlight_by_node() to get the backlight device.
- * Additionally if the brightness property is zero, it is set to
- * max_brightness.
- *
- * Returns:
- * NULL if there's no backlight property.
- * Error pointer -EPROBE_DEFER if the DT node is found, but no backlight device
- * is found.
- * If the backlight device is found, a pointer to the structure is returned.
- */
-struct backlight_device *tinydrm_of_find_backlight(struct device *dev)
-{
-	struct backlight_device *backlight;
-	struct device_node *np;
-
-	np = of_parse_phandle(dev->of_node, "backlight", 0);
-	if (!np)
-		return NULL;
-
-	backlight = of_find_backlight_by_node(np);
-	of_node_put(np);
-
-	if (!backlight)
-		return ERR_PTR(-EPROBE_DEFER);
-
-	if (!backlight->props.brightness) {
-		backlight->props.brightness = backlight->props.max_brightness;
-		DRM_DEBUG_KMS("Backlight brightness set to %d\n",
-			      backlight->props.brightness);
-	}
-
-	return backlight;
-}
-EXPORT_SYMBOL(tinydrm_of_find_backlight);
-
 #if IS_ENABLED(CONFIG_SPI)
 
 /**
diff --git a/drivers/gpu/drm/tinydrm/mi0283qt.c b/drivers/gpu/drm/tinydrm/mi0283qt.c
index 79cb5af5a..a8aafce36 100644
--- a/drivers/gpu/drm/tinydrm/mi0283qt.c
+++ b/drivers/gpu/drm/tinydrm/mi0283qt.c
@@ -9,6 +9,7 @@
  * (at your option) any later version.
  */
 
+#include <linux/backlight.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/module.h>
@@ -195,7 +196,7 @@ static int mi0283qt_probe(struct spi_device *spi)
 	if (IS_ERR(mipi->regulator))
 		return PTR_ERR(mipi->regulator);
 
-	mipi->backlight = tinydrm_of_find_backlight(dev);
+	mipi->backlight = of_find_backlight(dev);
 	if (IS_ERR(mipi->backlight))
 		return PTR_ERR(mipi->backlight);
 
diff --git a/drivers/gpu/drm/tinydrm/st7735r.c b/drivers/gpu/drm/tinydrm/st7735r.c
index 08b4fb18e..2e6b7b8ec 100644
--- a/drivers/gpu/drm/tinydrm/st7735r.c
+++ b/drivers/gpu/drm/tinydrm/st7735r.c
@@ -5,6 +5,7 @@
  * Copyright 2017 David Lechner <david@lechnology.com>
  */
 
+#include <linux/backlight.h>
 #include <linux/delay.h>
 #include <linux/dma-buf.h>
 #include <linux/gpio/consumer.h>
@@ -163,7 +164,7 @@ static int st7735r_probe(struct spi_device *spi)
 		return PTR_ERR(dc);
 	}
 
-	mipi->backlight = tinydrm_of_find_backlight(dev);
+	mipi->backlight = of_find_backlight(dev);
 	if (IS_ERR(mipi->backlight))
 		return PTR_ERR(mipi->backlight);
 
diff --git a/include/drm/tinydrm/tinydrm-helpers.h b/include/drm/tinydrm/tinydrm-helpers.h
index f54fae03e..0a4ddbc04 100644
--- a/include/drm/tinydrm/tinydrm-helpers.h
+++ b/include/drm/tinydrm/tinydrm-helpers.h
@@ -46,8 +46,6 @@ void tinydrm_xrgb8888_to_rgb565(u16 *dst, void *vaddr,
 void tinydrm_xrgb8888_to_gray8(u8 *dst, void *vaddr, struct drm_framebuffer *fb,
 			       struct drm_clip_rect *clip);
 
-struct backlight_device *tinydrm_of_find_backlight(struct device *dev);
-
 size_t tinydrm_spi_max_transfer_size(struct spi_device *spi, size_t max_len);
 bool tinydrm_spi_bpw_supported(struct spi_device *spi, u8 bpw);
 int tinydrm_spi_transfer(struct spi_device *spi, u32 speed_hz,
-- 
2.11.0

[PATCH v17 05/10] video: backlight: Add devres versions of of_find_backlight

[Meghana Madhyastha]

Add devm_of_find_backlight and the corresponding release
function because some drivers use devres versions of functions
for acquiring device resources.

Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
---
changes in v17:
-fix checkpath errors/warnings
-rename devm_backlight_put to 
 devm_backlight_release

 drivers/video/backlight/backlight.c | 30 ++++++++++++++++++++++++++++++
 include/linux/backlight.h           |  7 +++++++
 2 files changed, 37 insertions(+)

diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index 553bf5c48..deb824bef 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -623,6 +623,36 @@ struct backlight_device *of_find_backlight(struct device *dev)
 }
 EXPORT_SYMBOL(of_find_backlight);
 
+static void devm_backlight_release(void *data)
+{
+	backlight_put(data);
+}
+
+/**
+ * devm_of_find_backlight - Resource-managed of_find_backlight()
+ * @dev: Device
+ *
+ * Device managed version of of_find_backlight().
+ * The reference on the backlight device is automatically
+ * dropped on driver detach.
+ */
+struct backlight_device *devm_of_find_backlight(struct device *dev)
+{
+	struct backlight_device *bd;
+	int ret;
+
+	bd = of_find_backlight(dev);
+	if (IS_ERR_OR_NULL(bd))
+		return bd;
+	ret = devm_add_action(dev, devm_backlight_release, bd);
+	if (ret) {
+		backlight_put(bd);
+		return ERR_PTR(ret);
+	}
+	return bd;
+}
+EXPORT_SYMBOL(devm_of_find_backlight);
+
 static void __exit backlight_class_exit(void)
 {
 	class_destroy(backlight_class);
diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index ddc9bade4..2baab6f38 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -217,11 +217,18 @@ of_find_backlight_by_node(struct device_node *node)
 
 #if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
 struct backlight_device *of_find_backlight(struct device *dev);
+struct backlight_device *devm_of_find_backlight(struct device *dev);
 #else
 static inline struct backlight_device *of_find_backlight(struct device *dev)
 {
 	return NULL;
 }
+
+static inline struct backlight_device *
+devm_of_find_backlight(struct device *dev)
+{
+	return NULL;
+}
 #endif
 
 #endif
-- 
2.11.0

[PATCH v17 06/10] drm/tinydrm: Call devres version of of_find_backlight

[Meghana Madhyastha]

Call devm_of_find_backlight (the devres version) instead of
of_find_backlight.

Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
---
changes in v17:
-convert st7735r callers from tinydrm specific helpers
 to new generic backlight helpers

 drivers/gpu/drm/tinydrm/mi0283qt.c | 2 +-
 drivers/gpu/drm/tinydrm/st7735r.c  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tinydrm/mi0283qt.c b/drivers/gpu/drm/tinydrm/mi0283qt.c
index a8aafce36..d8ed6e6f8 100644
--- a/drivers/gpu/drm/tinydrm/mi0283qt.c
+++ b/drivers/gpu/drm/tinydrm/mi0283qt.c
@@ -196,7 +196,7 @@ static int mi0283qt_probe(struct spi_device *spi)
 	if (IS_ERR(mipi->regulator))
 		return PTR_ERR(mipi->regulator);
 
-	mipi->backlight = of_find_backlight(dev);
+	mipi->backlight = devm_of_find_backlight(dev);
 	if (IS_ERR(mipi->backlight))
 		return PTR_ERR(mipi->backlight);
 
diff --git a/drivers/gpu/drm/tinydrm/st7735r.c b/drivers/gpu/drm/tinydrm/st7735r.c
index 2e6b7b8ec..67d197ecf 100644
--- a/drivers/gpu/drm/tinydrm/st7735r.c
+++ b/drivers/gpu/drm/tinydrm/st7735r.c
@@ -164,7 +164,7 @@ static int st7735r_probe(struct spi_device *spi)
 		return PTR_ERR(dc);
 	}
 
-	mipi->backlight = of_find_backlight(dev);
+	mipi->backlight = devm_of_find_backlight(dev);
 	if (IS_ERR(mipi->backlight))
 		return PTR_ERR(mipi->backlight);
 
-- 
2.11.0

[PATCH v17 07/10] drm/panel: Use backlight_enable/disable helpers

[Meghana Madhyastha]

Use backlight_enable/disable helpers instead of changing
the property and calling backlight_update_status for cleaner
and simpler code and also to avoid repetitions.

Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
---
changes in v17:
-remove redundant NULL check

 drivers/gpu/drm/panel/panel-innolux-p079zca.c   |  6 ++----
 drivers/gpu/drm/panel/panel-jdi-lt070me05000.c  |  6 ++----
 drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c | 10 ++--------
 drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c | 10 ++--------
 4 files changed, 8 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-innolux-p079zca.c b/drivers/gpu/drm/panel/panel-innolux-p079zca.c
index 6ba93449f..4c1b29eec 100644
--- a/drivers/gpu/drm/panel/panel-innolux-p079zca.c
+++ b/drivers/gpu/drm/panel/panel-innolux-p079zca.c
@@ -45,8 +45,7 @@ static int innolux_panel_disable(struct drm_panel *panel)
 	if (!innolux->enabled)
 		return 0;
 
-	innolux->backlight->props.power = FB_BLANK_POWERDOWN;
-	backlight_update_status(innolux->backlight);
+	backlight_disable(innolux->backlight);
 
 	err = mipi_dsi_dcs_set_display_off(innolux->link);
 	if (err < 0)
@@ -151,8 +150,7 @@ static int innolux_panel_enable(struct drm_panel *panel)
 	if (innolux->enabled)
 		return 0;
 
-	innolux->backlight->props.power = FB_BLANK_UNBLANK;
-	ret = backlight_update_status(innolux->backlight);
+	ret = backlight_enable(innolux->backlight);
 	if (ret) {
 		DRM_DEV_ERROR(panel->drm->dev,
 			      "Failed to enable backlight %d\n", ret);
diff --git a/drivers/gpu/drm/panel/panel-jdi-lt070me05000.c b/drivers/gpu/drm/panel/panel-jdi-lt070me05000.c
index 5b2340ef7..0a94ab79a 100644
--- a/drivers/gpu/drm/panel/panel-jdi-lt070me05000.c
+++ b/drivers/gpu/drm/panel/panel-jdi-lt070me05000.c
@@ -192,8 +192,7 @@ static int jdi_panel_disable(struct drm_panel *panel)
 	if (!jdi->enabled)
 		return 0;
 
-	jdi->backlight->props.power = FB_BLANK_POWERDOWN;
-	backlight_update_status(jdi->backlight);
+	backlight_disable(jdi->backlight);
 
 	jdi->enabled = false;
 
@@ -289,8 +288,7 @@ static int jdi_panel_enable(struct drm_panel *panel)
 	if (jdi->enabled)
 		return 0;
 
-	jdi->backlight->props.power = FB_BLANK_UNBLANK;
-	backlight_update_status(jdi->backlight);
+	backlight_enable(jdi->backlight);
 
 	jdi->enabled = true;
 
diff --git a/drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c b/drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c
index 3cce3ca19..072c0fc79 100644
--- a/drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c
+++ b/drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c
@@ -96,10 +96,7 @@ static int sharp_panel_disable(struct drm_panel *panel)
 	if (!sharp->enabled)
 		return 0;
 
-	if (sharp->backlight) {
-		sharp->backlight->props.power = FB_BLANK_POWERDOWN;
-		backlight_update_status(sharp->backlight);
-	}
+	backlight_disable(sharp->backlight);
 
 	sharp->enabled = false;
 
@@ -263,10 +260,7 @@ static int sharp_panel_enable(struct drm_panel *panel)
 	if (sharp->enabled)
 		return 0;
 
-	if (sharp->backlight) {
-		sharp->backlight->props.power = FB_BLANK_UNBLANK;
-		backlight_update_status(sharp->backlight);
-	}
+	backlight_enable(sharp->backlight);
 
 	sharp->enabled = true;
 
diff --git a/drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c b/drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c
index 3aeb0bda4..8a5137963 100644
--- a/drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c
+++ b/drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c
@@ -117,10 +117,7 @@ static int sharp_nt_panel_disable(struct drm_panel *panel)
 	if (!sharp_nt->enabled)
 		return 0;
 
-	if (sharp_nt->backlight) {
-		sharp_nt->backlight->props.power = FB_BLANK_POWERDOWN;
-		backlight_update_status(sharp_nt->backlight);
-	}
+	backlight_disable(sharp_nt->backlight);
 
 	sharp_nt->enabled = false;
 
@@ -203,10 +200,7 @@ static int sharp_nt_panel_enable(struct drm_panel *panel)
 	if (sharp_nt->enabled)
 		return 0;
 
-	if (sharp_nt->backlight) {
-		sharp_nt->backlight->props.power = FB_BLANK_UNBLANK;
-		backlight_update_status(sharp_nt->backlight);
-	}
+	backlight_enable(sharp_nt->backlight);
 
 	sharp_nt->enabled = true;
 
-- 
2.11.0

[PATCH v17 08/10] drm/omapdrm: Use backlight_enable/disable helpers

[Meghana Madhyastha]

Use backlight_enable/disable helpers instead of changing
the property and calling backlight_update_status for cleaner
and simpler code and also to avoid repetitions.

Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
---
changes in v17:
-remove redundant NULL check

 drivers/gpu/drm/omapdrm/displays/panel-dpi.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/omapdrm/displays/panel-dpi.c b/drivers/gpu/drm/omapdrm/displays/panel-dpi.c
index e065f7e10..ac9596251 100644
--- a/drivers/gpu/drm/omapdrm/displays/panel-dpi.c
+++ b/drivers/gpu/drm/omapdrm/displays/panel-dpi.c
@@ -87,11 +87,7 @@ static int panel_dpi_enable(struct omap_dss_device *dssdev)
 	}
 
 	gpiod_set_value_cansleep(ddata->enable_gpio, 1);
-
-	if (ddata->backlight) {
-		ddata->backlight->props.power = FB_BLANK_UNBLANK;
-		backlight_update_status(ddata->backlight);
-	}
+	backlight_enable(ddata->backlight);
 
 	dssdev->state = OMAP_DSS_DISPLAY_ACTIVE;
 
@@ -106,10 +102,7 @@ static void panel_dpi_disable(struct omap_dss_device *dssdev)
 	if (!omapdss_device_is_enabled(dssdev))
 		return;
 
-	if (ddata->backlight) {
-		ddata->backlight->props.power = FB_BLANK_POWERDOWN;
-		backlight_update_status(ddata->backlight);
-	}
+	backlight_disable(ddata->backlight);
 
 	gpiod_set_value_cansleep(ddata->enable_gpio, 0);
 	regulator_disable(ddata->vcc_supply);
-- 
2.11.0

[PATCH v17 09/10] drm/panel: Use of_find_backlight helper

[Meghana Madhyastha]

Replace of_find_backlight_by_node and of the code around it
with of_find_backlight helper to avoid repetition of code.

Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
---
changes in v17:
-remove put_device() to avoid double put 
 as we are using the devm version

 drivers/gpu/drm/panel/panel-innolux-p079zca.c   | 23 ++++-------------------
 drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c | 25 ++++---------------------
 drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c | 25 ++++---------------------
 3 files changed, 12 insertions(+), 61 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-innolux-p079zca.c b/drivers/gpu/drm/panel/panel-innolux-p079zca.c
index 4c1b29eec..059f4af1a 100644
--- a/drivers/gpu/drm/panel/panel-innolux-p079zca.c
+++ b/drivers/gpu/drm/panel/panel-innolux-p079zca.c
@@ -230,37 +230,22 @@ static int innolux_panel_add(struct innolux_panel *innolux)
 		innolux->enable_gpio = NULL;
 	}
 
-	np = of_parse_phandle(dev->of_node, "backlight", 0);
-	if (np) {
-		innolux->backlight = of_find_backlight_by_node(np);
-		of_node_put(np);
+	innolux->backlight = devm_of_find_backlight(np);
 
-		if (!innolux->backlight)
-			return -EPROBE_DEFER;
-	}
+	if (IS_ERR(innolux->backlight))
+		return PTR_ERR(innolux->backlight);
 
 	drm_panel_init(&innolux->base);
 	innolux->base.funcs = &innolux_panel_funcs;
 	innolux->base.dev = &innolux->link->dev;
 
-	err = drm_panel_add(&innolux->base);
-	if (err < 0)
-		goto put_backlight;
-
-	return 0;
-
-put_backlight:
-	put_device(&innolux->backlight->dev);
-
-	return err;
+	return drm_panel_add(&innolux->base);
 }
 
 static void innolux_panel_del(struct innolux_panel *innolux)
 {
 	if (innolux->base.dev)
 		drm_panel_remove(&innolux->base);
-
-	put_device(&innolux->backlight->dev);
 }
 
 static int innolux_panel_probe(struct mipi_dsi_device *dsi)
diff --git a/drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c b/drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c
index 072c0fc79..85279d224 100644
--- a/drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c
+++ b/drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c
@@ -327,30 +327,16 @@ static int sharp_panel_add(struct sharp_panel *sharp)
 	if (IS_ERR(sharp->supply))
 		return PTR_ERR(sharp->supply);
 
-	np = of_parse_phandle(sharp->link1->dev.of_node, "backlight", 0);
-	if (np) {
-		sharp->backlight = of_find_backlight_by_node(np);
-		of_node_put(np);
+	sharp->backlight = devm_of_find_backlight(np);
 
-		if (!sharp->backlight)
-			return -EPROBE_DEFER;
-	}
+	if (IS_ERR(sharp->backlight))
+		return PTR_ERR(sharp->backlight);
 
 	drm_panel_init(&sharp->base);
 	sharp->base.funcs = &sharp_panel_funcs;
 	sharp->base.dev = &sharp->link1->dev;
 
-	err = drm_panel_add(&sharp->base);
-	if (err < 0)
-		goto put_backlight;
-
-	return 0;
-
-put_backlight:
-	if (sharp->backlight)
-		put_device(&sharp->backlight->dev);
-
-	return err;
+	return drm_panel_add(&sharp->base);
 }
 
 static void sharp_panel_del(struct sharp_panel *sharp)
@@ -358,9 +344,6 @@ static void sharp_panel_del(struct sharp_panel *sharp)
 	if (sharp->base.dev)
 		drm_panel_remove(&sharp->base);
 
-	if (sharp->backlight)
-		put_device(&sharp->backlight->dev);
-
 	if (sharp->link2)
 		put_device(&sharp->link2->dev);
 }
diff --git a/drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c b/drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c
index 8a5137963..b634ec887 100644
--- a/drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c
+++ b/drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c
@@ -271,39 +271,22 @@ static int sharp_nt_panel_add(struct sharp_nt_panel *sharp_nt)
 		gpiod_set_value(sharp_nt->reset_gpio, 0);
 	}
 
-	np = of_parse_phandle(dev->of_node, "backlight", 0);
-	if (np) {
-		sharp_nt->backlight = of_find_backlight_by_node(np);
-		of_node_put(np);
+	sharp_nt->backlight = devm_of_find_backlight(np);
 
-		if (!sharp_nt->backlight)
-			return -EPROBE_DEFER;
-	}
+	if (IS_ERR(sharp_nt->backlight))
+		return PTR_ERR(sharp_nt->backlight);
 
 	drm_panel_init(&sharp_nt->base);
 	sharp_nt->base.funcs = &sharp_nt_panel_funcs;
 	sharp_nt->base.dev = &sharp_nt->dsi->dev;
 
-	ret = drm_panel_add(&sharp_nt->base);
-	if (ret < 0)
-		goto put_backlight;
-
-	return 0;
-
-put_backlight:
-	if (sharp_nt->backlight)
-		put_device(&sharp_nt->backlight->dev);
-
-	return ret;
+	return drm_panel_add(&sharp_nt->base);
 }
 
 static void sharp_nt_panel_del(struct sharp_nt_panel *sharp_nt)
 {
 	if (sharp_nt->base.dev)
 		drm_panel_remove(&sharp_nt->base);
-
-	if (sharp_nt->backlight)
-		put_device(&sharp_nt->backlight->dev);
 }
 
 static int sharp_nt_panel_probe(struct mipi_dsi_device *dsi)
-- 
2.11.0

[PATCH v17 10/10] drm/omapdrm: Use of_find_backlight helper

[Meghana Madhyastha]

Replace of_find_backlight_by_node and of the code around it
with of_find_backlight helper to avoid repetition of code.

Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
---
changes in v17:
-remove put_device() to avoid double put 
 as we are using the devm version

 drivers/gpu/drm/omapdrm/displays/panel-dpi.c | 21 +++++----------------
 1 file changed, 5 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/omapdrm/displays/panel-dpi.c b/drivers/gpu/drm/omapdrm/displays/panel-dpi.c
index ac9596251..4d598167f 100644
--- a/drivers/gpu/drm/omapdrm/displays/panel-dpi.c
+++ b/drivers/gpu/drm/omapdrm/displays/panel-dpi.c
@@ -183,19 +183,15 @@ static int panel_dpi_probe_of(struct platform_device *pdev)
 	if (IS_ERR(ddata->vcc_supply))
 		return PTR_ERR(ddata->vcc_supply);
 
-	bl_node = of_parse_phandle(node, "backlight", 0);
-	if (bl_node) {
-		ddata->backlight = of_find_backlight_by_node(bl_node);
-		of_node_put(bl_node);
+	ddata->backlight = of_find_backlight(bl_node);
 
-		if (!ddata->backlight)
-			return -EPROBE_DEFER;
-	}
+	if (IS_ERR(ddata->backlight))
+		return PTR_ERR(ddata->backlight);
 
 	r = of_get_display_timing(node, "panel-timing", &timing);
 	if (r) {
 		dev_err(&pdev->dev, "failed to get video timing\n");
-		goto error_free_backlight;
+		return r;
 	}
 
 	videomode_from_timing(&timing, &ddata->vm);
@@ -203,19 +199,12 @@ static int panel_dpi_probe_of(struct platform_device *pdev)
 	in = omapdss_of_find_source_for_first_ep(node);
 	if (IS_ERR(in)) {
 		dev_err(&pdev->dev, "failed to find video source\n");
-		r = PTR_ERR(in);
-		goto error_free_backlight;
+		return PTR_ERR(in);
 	}
 
 	ddata->in = in;
 
 	return 0;
-
-error_free_backlight:
-	if (ddata->backlight)
-		put_device(&ddata->backlight->dev);
-
-	return r;
 }
 
 static int panel_dpi_probe(struct platform_device *pdev)
-- 
2.11.0

Re: [PATCH v17 01/10] video: backlight: Add helpers to enable and disable backlight

[Daniel Thompson]

On Fri, Jan 19, 2018 at 10:39:16AM +0000, Meghana Madhyastha wrote:
> Add helper functions backlight_enable and backlight_disable to
> enable/disable a backlight device. These helper functions can
> then be used by different drm and tinydrm drivers to avoid
> repetition of code and also to enforce a uniform and consistent
> way to enable/disable a backlight device.
> 
> Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>

Acked-by: Daniel Thompson <daniel.thompson@linaro.org>

BTW Lee J. looks PRs and merges for the backlight tree, I'll leave it 
to Lee and whoevers-DRM-tree-this-would-naturally-land-in to decide the 
merge path.


Daniel.

> ---
> changes in v17:
> -set fb_blank along with clearing the BL_CORE_FBBLANK bit
> 
>  include/linux/backlight.h | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
> 
> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> index af7003548..ace825e2c 100644
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -130,6 +130,38 @@ static inline int backlight_update_status(struct backlight_device *bd)
>  	return ret;
>  }
>  
> +/**
> + * backlight_enable - Enable backlight
> + * @bd: the backlight device to enable
> + */
> +static inline int backlight_enable(struct backlight_device *bd)
> +{
> +	if (!bd)
> +		return 0;
> +
> +	bd->props.power = FB_BLANK_UNBLANK;
> +	bd->props.fb_blank = FB_BLANK_UNBLANK;
> +	bd->props.state &= ~BL_CORE_FBBLANK;
> +
> +	return backlight_update_status(bd);
> +}
> +
> +/**
> + * backlight_disable - Disable backlight
> + * @bd: the backlight device to disable
> + */
> +static inline int backlight_disable(struct backlight_device *bd)
> +{
> +	if (!bd)
> +		return 0;
> +
> +	bd->props.power = FB_BLANK_POWERDOWN;
> +	bd->props.fb_blank = FB_BLANK_POWERDOWN;
> +	bd->props.state |= BL_CORE_FBBLANK;
> +
> +	return backlight_update_status(bd);
> +}
> +
>  extern struct backlight_device *backlight_device_register(const char *name,
>  	struct device *dev, void *devdata, const struct backlight_ops *ops,
>  	const struct backlight_properties *props);
> -- 
> 2.11.0
> 

Re: [PATCH v17 03/10] video: backlight: Add of_find_backlight helper in backlight.c

[Daniel Thompson]

On Fri, Jan 19, 2018 at 10:42:15AM +0000, Meghana Madhyastha wrote:
> Add of_find_backlight, a helper function which is a generic version
> of tinydrm_of_find_backlight that can be used by other drivers to avoid
> repetition of code and simplify things.
> 
> Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>

Didn't I already ack this one?


> ---
> changes in v17:
> -rebase with drm-misc-next
> -convert st7735r callers from tinydrm specific helpers
>  to new generic backlight helpers
> -remove select BACKLIGHT_LCD_SUPPORT
>  and select BACKLIGHT_CLASS_DEVICE from
>  tinydrm/Kconfig
> 
>  drivers/video/backlight/backlight.c | 43 +++++++++++++++++++++++++++++++++++++
>  include/linux/backlight.h           | 19 ++++++++++++++++
>  2 files changed, 62 insertions(+)
> 
> diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
> index 8049e7656..553bf5c48 100644
> --- a/drivers/video/backlight/backlight.c
> +++ b/drivers/video/backlight/backlight.c
> @@ -580,6 +580,49 @@ struct backlight_device *of_find_backlight_by_node(struct device_node *node)
>  EXPORT_SYMBOL(of_find_backlight_by_node);
>  #endif
>  
> +/**
> + * of_find_backlight - Get backlight device
> + * @dev: Device
> + *
> + * This function looks for a property named 'backlight' on the DT node
> + * connected to @dev and looks up the backlight device.
> + *
> + * Call backlight_put() to drop the reference on the backlight device.
> + *
> + * Returns:
> + * A pointer to the backlight device if found.
> + * Error pointer -EPROBE_DEFER if the DT property is set, but no backlight
> + * device is found.
> + * NULL if there's no backlight property.
> + */
> +struct backlight_device *of_find_backlight(struct device *dev)
> +{
> +	struct backlight_device *bd = NULL;
> +	struct device_node *np;
> +
> +	if (!dev)
> +		return NULL;
> +
> +	if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
> +		np = of_parse_phandle(dev->of_node, "backlight", 0);
> +		if (np) {
> +			bd = of_find_backlight_by_node(np);
> +			of_node_put(np);
> +			if (!bd)
> +				return ERR_PTR(-EPROBE_DEFER);
> +			/*
> +			 * Note: gpio_backlight uses brightness as
> +			 * power state during probe
> +			 */
> +			if (!bd->props.brightness)
> +				bd->props.brightness = bd->props.max_brightness;
> +		}
> +	}
> +
> +	return bd;
> +}
> +EXPORT_SYMBOL(of_find_backlight);
> +
>  static void __exit backlight_class_exit(void)
>  {
>  	class_destroy(backlight_class);
> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> index ace825e2c..ddc9bade4 100644
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -162,6 +162,16 @@ static inline int backlight_disable(struct backlight_device *bd)
>  	return backlight_update_status(bd);
>  }
>  
> +/**
> + * backlight_put - Drop backlight reference
> + * @bd: the backlight device to put
> + */
> +static inline void backlight_put(struct backlight_device *bd)
> +{
> +	if (bd)
> +		put_device(&bd->dev);
> +}
> +
>  extern struct backlight_device *backlight_device_register(const char *name,
>  	struct device *dev, void *devdata, const struct backlight_ops *ops,
>  	const struct backlight_properties *props);
> @@ -205,4 +215,13 @@ of_find_backlight_by_node(struct device_node *node)
>  }
>  #endif
>  
> +#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
> +struct backlight_device *of_find_backlight(struct device *dev);
> +#else
> +static inline struct backlight_device *of_find_backlight(struct device *dev)
> +{
> +	return NULL;
> +}
> +#endif
> +
>  #endif
> -- 
> 2.11.0
> 

Re: [PATCH v17 05/10] video: backlight: Add devres versions of of_find_backlight

[Daniel Thompson]

On Fri, Jan 19, 2018 at 10:44:33AM +0000, Meghana Madhyastha wrote:
> Add devm_of_find_backlight and the corresponding release
> function because some drivers use devres versions of functions
> for acquiring device resources.
> 
> Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>

Acked-by: Daniel Thompson <daniel.thompson@linaro.org>


> ---
> changes in v17:
> -fix checkpath errors/warnings
> -rename devm_backlight_put to 
>  devm_backlight_release
> 
>  drivers/video/backlight/backlight.c | 30 ++++++++++++++++++++++++++++++
>  include/linux/backlight.h           |  7 +++++++
>  2 files changed, 37 insertions(+)
> 
> diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
> index 553bf5c48..deb824bef 100644
> --- a/drivers/video/backlight/backlight.c
> +++ b/drivers/video/backlight/backlight.c
> @@ -623,6 +623,36 @@ struct backlight_device *of_find_backlight(struct device *dev)
>  }
>  EXPORT_SYMBOL(of_find_backlight);
>  
> +static void devm_backlight_release(void *data)
> +{
> +	backlight_put(data);
> +}
> +
> +/**
> + * devm_of_find_backlight - Resource-managed of_find_backlight()
> + * @dev: Device
> + *
> + * Device managed version of of_find_backlight().
> + * The reference on the backlight device is automatically
> + * dropped on driver detach.
> + */
> +struct backlight_device *devm_of_find_backlight(struct device *dev)
> +{
> +	struct backlight_device *bd;
> +	int ret;
> +
> +	bd = of_find_backlight(dev);
> +	if (IS_ERR_OR_NULL(bd))
> +		return bd;
> +	ret = devm_add_action(dev, devm_backlight_release, bd);
> +	if (ret) {
> +		backlight_put(bd);
> +		return ERR_PTR(ret);
> +	}
> +	return bd;
> +}
> +EXPORT_SYMBOL(devm_of_find_backlight);
> +
>  static void __exit backlight_class_exit(void)
>  {
>  	class_destroy(backlight_class);
> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> index ddc9bade4..2baab6f38 100644
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -217,11 +217,18 @@ of_find_backlight_by_node(struct device_node *node)
>  
>  #if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
>  struct backlight_device *of_find_backlight(struct device *dev);
> +struct backlight_device *devm_of_find_backlight(struct device *dev);
>  #else
>  static inline struct backlight_device *of_find_backlight(struct device *dev)
>  {
>  	return NULL;
>  }
> +
> +static inline struct backlight_device *
> +devm_of_find_backlight(struct device *dev)
> +{
> +	return NULL;
> +}
>  #endif
>  
>  #endif
> -- 
> 2.11.0
> 

Re: [PATCH v17 00/10] Add backlight helper functions

[Daniel Thompson]

On Fri, Jan 19, 2018 at 10:37:58AM +0000, Meghana Madhyastha wrote:
> Move drm helper functions from tinydrm-helpers to linux/backlight for
> ease of use by callers in other drivers.
> 
> changes in v17:
> -set fb_blank along with clearing the BL_CORE_FBBLANK bit 
> -rebase with drm-misc-next
> -fix checkpath errors/warnings
> -Make the gpio_backlight issue appear as a comment in the
>  code and not as part of the docs
> -rebase with drm-misc-next
> -convert st7735r callers from tinydrm specific helpers
>  to new generic backlight helpers
> -remove select BACKLIGHT_LCD_SUPPORT and select 
>  BACKLIGHT_CLASS_DEVICE from tinydrm/Kconfig
> -fix checkpath errors/warnings
> -rename devm_backlight_put to 
>  devm_backlight_release
> -remove redundant NULL check
> -remove put_device() to avoid double put 
>  as we are using the devm version
> 
> Meghana Madhyastha (10):
>   video: backlight: Add helpers to enable and disable backlight
>   drm/tinydrm: Convert tinydrm_enable/disable_backlight to
>     backlight_enable/disable
>   video: backlight: Add of_find_backlight helper in backlight.c
>   drm/tinydrm: Replace tinydrm_of_find_backlight with of_find_backlight
>   video: backlight: Add devres versions of of_find_backlight
>   drm/tinydrm: Call devres version of of_find_backlight
>   drm/panel: Use backlight_enable/disable helpers
>   drm/omapdrm: Use backlight_enable/disable helpers
>   drm/panel: Use of_find_backlight helper
>   drm/omapdrm: Use of_find_backlight helper

So, I've acked all the backlight bits (if there's a v18 please include
the acks in the posting).

I've read the other patches and I *like* them. Switching to 
backlight_enable()/disable() looks like a good way to ensure
drivers don't interact with all those flags in unexpected ways
(so its a good contribution to eventually cleaning them up).


Daniel.


> 
>  drivers/gpu/drm/omapdrm/displays/panel-dpi.c    | 32 ++-------
>  drivers/gpu/drm/panel/panel-innolux-p079zca.c   | 29 ++------
>  drivers/gpu/drm/panel/panel-jdi-lt070me05000.c  |  6 +-
>  drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c | 35 ++-------
>  drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c | 35 ++-------
>  drivers/gpu/drm/tinydrm/Kconfig                 |  2 -
>  drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c  | 95 -------------------------
>  drivers/gpu/drm/tinydrm/mi0283qt.c              |  3 +-
>  drivers/gpu/drm/tinydrm/mipi-dbi.c              |  4 +-
>  drivers/gpu/drm/tinydrm/st7735r.c               |  3 +-
>  drivers/video/backlight/backlight.c             | 73 +++++++++++++++++++
>  include/drm/tinydrm/tinydrm-helpers.h           |  4 --
>  include/linux/backlight.h                       | 58 +++++++++++++++
>  13 files changed, 164 insertions(+), 215 deletions(-)
> 
> -- 
> 2.11.0
> 

Re: [PATCH v17 01/10] video: backlight: Add helpers to enable and disable backlight

[Lee Jones]

On Fri, 19 Jan 2018, Daniel Thompson wrote:

> On Fri, Jan 19, 2018 at 10:39:16AM +0000, Meghana Madhyastha wrote:
> > Add helper functions backlight_enable and backlight_disable to
> > enable/disable a backlight device. These helper functions can
> > then be used by different drm and tinydrm drivers to avoid
> > repetition of code and also to enforce a uniform and consistent
> > way to enable/disable a backlight device.
> > 
> > Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
> 
> Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
> 
> BTW Lee J. looks PRs and merges for the backlight tree, I'll leave it 
> to Lee and whoevers-DRM-tree-this-would-naturally-land-in to decide the 
> merge path.

So the choices are; either I take the set and send out a pull-request
which can be subsequently merged into the DRM repo, OR they are
applied into an immutable branch in the DRM tree and I can pull that
in instead.

Don't really mind which.

-- 
Lee Jones
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

Re: [PATCH v17 03/10] video: backlight: Add of_find_backlight helper in backlight.c

[Noralf Trønnes]

Den 19.01.2018 12.05, skrev Daniel Thompson:
> On Fri, Jan 19, 2018 at 10:42:15AM +0000, Meghana Madhyastha wrote:
>> Add of_find_backlight, a helper function which is a generic version
>> of tinydrm_of_find_backlight that can be used by other drivers to avoid
>> repetition of code and simplify things.
>>
>> Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
> Didn't I already ack this one?

Meghana,

You are supposed to pick up the r-b/acks you get and add them when you send
a new version. This way the reviewer knows which patches still need 
attention.

Here's a good overview of the acks/r-b's you've received:
https://patchwork.freedesktop.org/project/dri-devel/patches/?submitter=17149

Beware that r-b/ack to the cover letter doesn't show up in patchwork, like
Sean did on the last version putting his r-b on the whole series.
The same goes for someone putting an r-b in one of the patches stating that
it applies to whole series, patchwork thinks it only applies to this one 
patch.

Noralf.

>
>> ---
>> changes in v17:
>> -rebase with drm-misc-next
>> -convert st7735r callers from tinydrm specific helpers
>>   to new generic backlight helpers
>> -remove select BACKLIGHT_LCD_SUPPORT
>>   and select BACKLIGHT_CLASS_DEVICE from
>>   tinydrm/Kconfig
>>
>>   drivers/video/backlight/backlight.c | 43 +++++++++++++++++++++++++++++++++++++
>>   include/linux/backlight.h           | 19 ++++++++++++++++
>>   2 files changed, 62 insertions(+)
>>
>> diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
>> index 8049e7656..553bf5c48 100644
>> --- a/drivers/video/backlight/backlight.c
>> +++ b/drivers/video/backlight/backlight.c
>> @@ -580,6 +580,49 @@ struct backlight_device *of_find_backlight_by_node(struct device_node *node)
>>   EXPORT_SYMBOL(of_find_backlight_by_node);
>>   #endif
>>   
>> +/**
>> + * of_find_backlight - Get backlight device
>> + * @dev: Device
>> + *
>> + * This function looks for a property named 'backlight' on the DT node
>> + * connected to @dev and looks up the backlight device.
>> + *
>> + * Call backlight_put() to drop the reference on the backlight device.
>> + *
>> + * Returns:
>> + * A pointer to the backlight device if found.
>> + * Error pointer -EPROBE_DEFER if the DT property is set, but no backlight
>> + * device is found.
>> + * NULL if there's no backlight property.
>> + */
>> +struct backlight_device *of_find_backlight(struct device *dev)
>> +{
>> +	struct backlight_device *bd = NULL;
>> +	struct device_node *np;
>> +
>> +	if (!dev)
>> +		return NULL;
>> +
>> +	if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
>> +		np = of_parse_phandle(dev->of_node, "backlight", 0);
>> +		if (np) {
>> +			bd = of_find_backlight_by_node(np);
>> +			of_node_put(np);
>> +			if (!bd)
>> +				return ERR_PTR(-EPROBE_DEFER);
>> +			/*
>> +			 * Note: gpio_backlight uses brightness as
>> +			 * power state during probe
>> +			 */
>> +			if (!bd->props.brightness)
>> +				bd->props.brightness = bd->props.max_brightness;
>> +		}
>> +	}
>> +
>> +	return bd;
>> +}
>> +EXPORT_SYMBOL(of_find_backlight);
>> +
>>   static void __exit backlight_class_exit(void)
>>   {
>>   	class_destroy(backlight_class);
>> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
>> index ace825e2c..ddc9bade4 100644
>> --- a/include/linux/backlight.h
>> +++ b/include/linux/backlight.h
>> @@ -162,6 +162,16 @@ static inline int backlight_disable(struct backlight_device *bd)
>>   	return backlight_update_status(bd);
>>   }
>>   
>> +/**
>> + * backlight_put - Drop backlight reference
>> + * @bd: the backlight device to put
>> + */
>> +static inline void backlight_put(struct backlight_device *bd)
>> +{
>> +	if (bd)
>> +		put_device(&bd->dev);
>> +}
>> +
>>   extern struct backlight_device *backlight_device_register(const char *name,
>>   	struct device *dev, void *devdata, const struct backlight_ops *ops,
>>   	const struct backlight_properties *props);
>> @@ -205,4 +215,13 @@ of_find_backlight_by_node(struct device_node *node)
>>   }
>>   #endif
>>   
>> +#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
>> +struct backlight_device *of_find_backlight(struct device *dev);
>> +#else
>> +static inline struct backlight_device *of_find_backlight(struct device *dev)
>> +{
>> +	return NULL;
>> +}
>> +#endif
>> +
>>   #endif
>> -- 
>> 2.11.0
>>

Re: [PATCH v17 09/10] drm/panel: Use of_find_backlight helper

[Noralf Trønnes]

Den 19.01.2018 11.47, skrev Meghana Madhyastha:
> Replace of_find_backlight_by_node and of the code around it
> with of_find_backlight helper to avoid repetition of code.
>
> Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
> ---
> changes in v17:
> -remove put_device() to avoid double put
>   as we are using the devm version
>
>   drivers/gpu/drm/panel/panel-innolux-p079zca.c   | 23 ++++-------------------
>   drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c | 25 ++++---------------------
>   drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c | 25 ++++---------------------
>   3 files changed, 12 insertions(+), 61 deletions(-)
>
> diff --git a/drivers/gpu/drm/panel/panel-innolux-p079zca.c b/drivers/gpu/drm/panel/panel-innolux-p079zca.c
> index 4c1b29eec..059f4af1a 100644
> --- a/drivers/gpu/drm/panel/panel-innolux-p079zca.c
> +++ b/drivers/gpu/drm/panel/panel-innolux-p079zca.c
> @@ -230,37 +230,22 @@ static int innolux_panel_add(struct innolux_panel *innolux)
>   		innolux->enable_gpio = NULL;
>   	}
>   
> -	np = of_parse_phandle(dev->of_node, "backlight", 0);
> -	if (np) {
> -		innolux->backlight = of_find_backlight_by_node(np);
> -		of_node_put(np);
> +	innolux->backlight = devm_of_find_backlight(np);

There are several errors in these two last patches, like this one:

/home/pi/dim-build/workdirs/drm-misc/linux-linus/drivers/gpu/drm/panel/panel-innolux-p079zca.c: 
In function 'innolux_panel_add':
/home/pi/dim-build/workdirs/drm-misc/linux-linus/drivers/gpu/drm/panel/panel-innolux-p079zca.c:233:46: 
warning: passing argument 1 of 'devm_of_find_backlight' from 
incompatible pointer type
   innolux->backlight = devm_of_find_backlight(np);

Instead of tracking down the build dependencies to get this driver built,
you can instead use these defconfigs and all DRM drivers should be built:
https://cgit.freedesktop.org/drm/drm-tip/tree/?h=rerere-cache

But not all drivers are built on every architecture.

Noralf.

>   
> -		if (!innolux->backlight)
> -			return -EPROBE_DEFER;
> -	}
> +	if (IS_ERR(innolux->backlight))
> +		return PTR_ERR(innolux->backlight);
>   
>   	drm_panel_init(&innolux->base);
>   	innolux->base.funcs = &innolux_panel_funcs;
>   	innolux->base.dev = &innolux->link->dev;
>   
> -	err = drm_panel_add(&innolux->base);
> -	if (err < 0)
> -		goto put_backlight;
> -
> -	return 0;
> -
> -put_backlight:
> -	put_device(&innolux->backlight->dev);
> -
> -	return err;
> +	return drm_panel_add(&innolux->base);
>   }
>   
>   static void innolux_panel_del(struct innolux_panel *innolux)
>   {
>   	if (innolux->base.dev)
>   		drm_panel_remove(&innolux->base);
> -
> -	put_device(&innolux->backlight->dev);
>   }
>   
>   static int innolux_panel_probe(struct mipi_dsi_device *dsi)
> diff --git a/drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c b/drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c
> index 072c0fc79..85279d224 100644
> --- a/drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c
> +++ b/drivers/gpu/drm/panel/panel-sharp-lq101r1sx01.c
> @@ -327,30 +327,16 @@ static int sharp_panel_add(struct sharp_panel *sharp)
>   	if (IS_ERR(sharp->supply))
>   		return PTR_ERR(sharp->supply);
>   
> -	np = of_parse_phandle(sharp->link1->dev.of_node, "backlight", 0);
> -	if (np) {
> -		sharp->backlight = of_find_backlight_by_node(np);
> -		of_node_put(np);
> +	sharp->backlight = devm_of_find_backlight(np);
>   
> -		if (!sharp->backlight)
> -			return -EPROBE_DEFER;
> -	}
> +	if (IS_ERR(sharp->backlight))
> +		return PTR_ERR(sharp->backlight);
>   
>   	drm_panel_init(&sharp->base);
>   	sharp->base.funcs = &sharp_panel_funcs;
>   	sharp->base.dev = &sharp->link1->dev;
>   
> -	err = drm_panel_add(&sharp->base);
> -	if (err < 0)
> -		goto put_backlight;
> -
> -	return 0;
> -
> -put_backlight:
> -	if (sharp->backlight)
> -		put_device(&sharp->backlight->dev);
> -
> -	return err;
> +	return drm_panel_add(&sharp->base);
>   }
>   
>   static void sharp_panel_del(struct sharp_panel *sharp)
> @@ -358,9 +344,6 @@ static void sharp_panel_del(struct sharp_panel *sharp)
>   	if (sharp->base.dev)
>   		drm_panel_remove(&sharp->base);
>   
> -	if (sharp->backlight)
> -		put_device(&sharp->backlight->dev);
> -
>   	if (sharp->link2)
>   		put_device(&sharp->link2->dev);
>   }
> diff --git a/drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c b/drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c
> index 8a5137963..b634ec887 100644
> --- a/drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c
> +++ b/drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c
> @@ -271,39 +271,22 @@ static int sharp_nt_panel_add(struct sharp_nt_panel *sharp_nt)
>   		gpiod_set_value(sharp_nt->reset_gpio, 0);
>   	}
>   
> -	np = of_parse_phandle(dev->of_node, "backlight", 0);
> -	if (np) {
> -		sharp_nt->backlight = of_find_backlight_by_node(np);
> -		of_node_put(np);
> +	sharp_nt->backlight = devm_of_find_backlight(np);
>   
> -		if (!sharp_nt->backlight)
> -			return -EPROBE_DEFER;
> -	}
> +	if (IS_ERR(sharp_nt->backlight))
> +		return PTR_ERR(sharp_nt->backlight);
>   
>   	drm_panel_init(&sharp_nt->base);
>   	sharp_nt->base.funcs = &sharp_nt_panel_funcs;
>   	sharp_nt->base.dev = &sharp_nt->dsi->dev;
>   
> -	ret = drm_panel_add(&sharp_nt->base);
> -	if (ret < 0)
> -		goto put_backlight;
> -
> -	return 0;
> -
> -put_backlight:
> -	if (sharp_nt->backlight)
> -		put_device(&sharp_nt->backlight->dev);
> -
> -	return ret;
> +	return drm_panel_add(&sharp_nt->base);
>   }
>   
>   static void sharp_nt_panel_del(struct sharp_nt_panel *sharp_nt)
>   {
>   	if (sharp_nt->base.dev)
>   		drm_panel_remove(&sharp_nt->base);
> -
> -	if (sharp_nt->backlight)
> -		put_device(&sharp_nt->backlight->dev);
>   }
>   
>   static int sharp_nt_panel_probe(struct mipi_dsi_device *dsi)

Re: [PATCH v17 06/10] drm/tinydrm: Call devres version of of_find_backlight

[Noralf Trønnes]

Den 19.01.2018 11.46, skrev Meghana Madhyastha:
> Call devm_of_find_backlight (the devres version) instead of
> of_find_backlight.
>
> Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
> ---

I already put my r-b on this one in the previous version, but now also:

Tested-by: Noralf Trønnes <noralf@tronnes.org>

I did also test with the backlight subsystem disabled.

> changes in v17:
> -convert st7735r callers from tinydrm specific helpers
>   to new generic backlight helpers
>
>   drivers/gpu/drm/tinydrm/mi0283qt.c | 2 +-
>   drivers/gpu/drm/tinydrm/st7735r.c  | 2 +-
>   2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/tinydrm/mi0283qt.c b/drivers/gpu/drm/tinydrm/mi0283qt.c
> index a8aafce36..d8ed6e6f8 100644
> --- a/drivers/gpu/drm/tinydrm/mi0283qt.c
> +++ b/drivers/gpu/drm/tinydrm/mi0283qt.c
> @@ -196,7 +196,7 @@ static int mi0283qt_probe(struct spi_device *spi)
>   	if (IS_ERR(mipi->regulator))
>   		return PTR_ERR(mipi->regulator);
>   
> -	mipi->backlight = of_find_backlight(dev);
> +	mipi->backlight = devm_of_find_backlight(dev);
>   	if (IS_ERR(mipi->backlight))
>   		return PTR_ERR(mipi->backlight);
>   
> diff --git a/drivers/gpu/drm/tinydrm/st7735r.c b/drivers/gpu/drm/tinydrm/st7735r.c
> index 2e6b7b8ec..67d197ecf 100644
> --- a/drivers/gpu/drm/tinydrm/st7735r.c
> +++ b/drivers/gpu/drm/tinydrm/st7735r.c
> @@ -164,7 +164,7 @@ static int st7735r_probe(struct spi_device *spi)
>   		return PTR_ERR(dc);
>   	}
>   
> -	mipi->backlight = of_find_backlight(dev);
> +	mipi->backlight = devm_of_find_backlight(dev);
>   	if (IS_ERR(mipi->backlight))
>   		return PTR_ERR(mipi->backlight);
>   

Re: [PATCH v17 03/10] video: backlight: Add of_find_backlight helper in backlight.c

[Noralf Trønnes]

Den 19.01.2018 11.42, skrev Meghana Madhyastha:
> Add of_find_backlight, a helper function which is a generic version
> of tinydrm_of_find_backlight that can be used by other drivers to avoid
> repetition of code and simplify things.
>
> Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
> ---

Reviewed-by: Noralf Trønnes <noralf@tronnes.org>

> changes in v17:
> -rebase with drm-misc-next
> -convert st7735r callers from tinydrm specific helpers
>   to new generic backlight helpers
> -remove select BACKLIGHT_LCD_SUPPORT
>   and select BACKLIGHT_CLASS_DEVICE from
>   tinydrm/Kconfig
>
>   drivers/video/backlight/backlight.c | 43 +++++++++++++++++++++++++++++++++++++
>   include/linux/backlight.h           | 19 ++++++++++++++++
>   2 files changed, 62 insertions(+)
>
> diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
> index 8049e7656..553bf5c48 100644
> --- a/drivers/video/backlight/backlight.c
> +++ b/drivers/video/backlight/backlight.c
> @@ -580,6 +580,49 @@ struct backlight_device *of_find_backlight_by_node(struct device_node *node)
>   EXPORT_SYMBOL(of_find_backlight_by_node);
>   #endif
>   
> +/**
> + * of_find_backlight - Get backlight device
> + * @dev: Device
> + *
> + * This function looks for a property named 'backlight' on the DT node
> + * connected to @dev and looks up the backlight device.
> + *
> + * Call backlight_put() to drop the reference on the backlight device.
> + *
> + * Returns:
> + * A pointer to the backlight device if found.
> + * Error pointer -EPROBE_DEFER if the DT property is set, but no backlight
> + * device is found.
> + * NULL if there's no backlight property.
> + */
> +struct backlight_device *of_find_backlight(struct device *dev)
> +{
> +	struct backlight_device *bd = NULL;
> +	struct device_node *np;
> +
> +	if (!dev)
> +		return NULL;
> +
> +	if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
> +		np = of_parse_phandle(dev->of_node, "backlight", 0);
> +		if (np) {
> +			bd = of_find_backlight_by_node(np);
> +			of_node_put(np);
> +			if (!bd)
> +				return ERR_PTR(-EPROBE_DEFER);
> +			/*
> +			 * Note: gpio_backlight uses brightness as
> +			 * power state during probe
> +			 */
> +			if (!bd->props.brightness)
> +				bd->props.brightness = bd->props.max_brightness;
> +		}
> +	}
> +
> +	return bd;
> +}
> +EXPORT_SYMBOL(of_find_backlight);
> +
>   static void __exit backlight_class_exit(void)
>   {
>   	class_destroy(backlight_class);
> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> index ace825e2c..ddc9bade4 100644
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -162,6 +162,16 @@ static inline int backlight_disable(struct backlight_device *bd)
>   	return backlight_update_status(bd);
>   }
>   
> +/**
> + * backlight_put - Drop backlight reference
> + * @bd: the backlight device to put
> + */
> +static inline void backlight_put(struct backlight_device *bd)
> +{
> +	if (bd)
> +		put_device(&bd->dev);
> +}
> +
>   extern struct backlight_device *backlight_device_register(const char *name,
>   	struct device *dev, void *devdata, const struct backlight_ops *ops,
>   	const struct backlight_properties *props);
> @@ -205,4 +215,13 @@ of_find_backlight_by_node(struct device_node *node)
>   }
>   #endif
>   
> +#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
> +struct backlight_device *of_find_backlight(struct device *dev);
> +#else
> +static inline struct backlight_device *of_find_backlight(struct device *dev)
> +{
> +	return NULL;
> +}
> +#endif
> +
>   #endif