[PATCH v11 0/3] Move backlight helper functions from tinydrm-helpers to linux/backlight

[PATCH v11 0/3] Move backlight helper functions from tinydrm-helpers to linux/backlight

[Meghana Madhyastha]

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

Changes in v11:
-Move over tinydrm_disable_backlight to backlight_disable in the caller
in mipi-dbi.c

Meghana Madhyastha (3):
  drm/tinydrm: Move helper functions from tinydrm-helpers to backlight.h
  drm/tinydrm: Move tinydrm_of_find_backlight to backlight.c
  drm/tinydrm: Add devres versions of backlight_get

 drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 95 --------------------------
 drivers/gpu/drm/tinydrm/mi0283qt.c             |  3 +-
 drivers/gpu/drm/tinydrm/mipi-dbi.c             |  5 +-
 drivers/video/backlight/backlight.c            | 71 +++++++++++++++++++
 include/drm/tinydrm/tinydrm-helpers.h          |  5 --
 include/linux/backlight.h                      | 55 +++++++++++++++
 6 files changed, 131 insertions(+), 103 deletions(-)

-- 
2.7.4

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[PATCH v11 1/3] drm/tinydrm: Move helper functions from tinydrm-helpers to backlight.h

[Meghana Madhyastha]

Move the helper functions enable_backlight and disable_backlight
from tinydrm-helpers.c to backlight.h as static inline functions so
that they can be used by other drivers.

Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
---
Changes in v11:
-Move over tinydrm_disable_backlight to backlight_disable in the caller
in mipi-dbi.c

 drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 55 --------------------------
 drivers/gpu/drm/tinydrm/mipi-dbi.c             |  5 ++-
 include/drm/tinydrm/tinydrm-helpers.h          |  2 -
 include/linux/backlight.h                      | 30 ++++++++++++++
 4 files changed, 33 insertions(+), 59 deletions(-)

diff --git a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
index bd6cce0..a42dee6 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 2caeabc..71b416b 100644
--- a/drivers/gpu/drm/tinydrm/mipi-dbi.c
+++ b/drivers/gpu/drm/tinydrm/mipi-dbi.c
@@ -11,6 +11,7 @@
 
 #include <drm/tinydrm/mipi-dbi.h>
 #include <drm/tinydrm/tinydrm-helpers.h>
+#include <linux/backlight.h>
 #include <linux/debugfs.h>
 #include <linux/dma-buf.h>
 #include <linux/gpio/consumer.h>
@@ -279,7 +280,7 @@ void mipi_dbi_pipe_enable(struct drm_simple_display_pipe *pipe,
 	if (fb)
 		fb->funcs->dirty(fb, NULL, 0, 0, NULL, 0);
 
-	tinydrm_enable_backlight(mipi->backlight);
+	backlight_enable(mipi->backlight);
 }
 EXPORT_SYMBOL(mipi_dbi_pipe_enable);
 
@@ -318,7 +319,7 @@ 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 d554ded..f54fae0 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);
diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index 5f2fd61..355e9f5 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -153,6 +153,36 @@ static inline void * bl_get_data(struct backlight_device *bl_dev)
 	return dev_get_drvdata(&bl_dev->dev);
 }
 
+/**
+ * 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.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.state |= BL_CORE_FBBLANK;
+
+	return backlight_update_status(bd);
+}
+
 struct generic_bl_info {
 	const char *name;
 	int max_intensity;
-- 
2.7.4

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[PATCH v11 2/3] drm/tinydrm: Move tinydrm_of_find_backlight to backlight.c

[Meghana Madhyastha]

Rename tinydrm_of_find_backlight to backlight_get and move it
to linux/backlight.c so that it can be used by other drivers.

Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
---
Changes in v11:
-None

 drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 40 --------------------------
 drivers/gpu/drm/tinydrm/mi0283qt.c             |  3 +-
 drivers/video/backlight/backlight.c            | 40 ++++++++++++++++++++++++++
 include/drm/tinydrm/tinydrm-helpers.h          |  3 --
 include/linux/backlight.h                      |  9 ++++++
 5 files changed, 51 insertions(+), 44 deletions(-)

diff --git a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
index a42dee6..cb1a01a 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 7e5bb7d..edf9502 100644
--- a/drivers/gpu/drm/tinydrm/mi0283qt.c
+++ b/drivers/gpu/drm/tinydrm/mi0283qt.c
@@ -12,6 +12,7 @@
 #include <drm/tinydrm/ili9341.h>
 #include <drm/tinydrm/mipi-dbi.h>
 #include <drm/tinydrm/tinydrm-helpers.h>
+#include <linux/backlight.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/module.h>
@@ -189,7 +190,7 @@ 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 = backlight_get(dev);
 	if (IS_ERR(mipi->backlight))
 		return PTR_ERR(mipi->backlight);
 
diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index 8049e76..1debb60 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -580,6 +580,46 @@ struct backlight_device *of_find_backlight_by_node(struct device_node *node)
 EXPORT_SYMBOL(of_find_backlight_by_node);
 #endif
 
+/**
+ * backlight_get - 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.
+ */
+
+#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
+struct backlight_device *backlight_get(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);
+		}
+	}
+
+	return bd;
+}
+EXPORT_SYMBOL(backlight_get);
+#endif
+
 static void __exit backlight_class_exit(void)
 {
 	class_destroy(backlight_class);
diff --git a/include/drm/tinydrm/tinydrm-helpers.h b/include/drm/tinydrm/tinydrm-helpers.h
index f54fae0..b89d8e4 100644
--- a/include/drm/tinydrm/tinydrm-helpers.h
+++ b/include/drm/tinydrm/tinydrm-helpers.h
@@ -10,7 +10,6 @@
 #ifndef __LINUX_TINYDRM_HELPERS_H
 #define __LINUX_TINYDRM_HELPERS_H
 
-struct backlight_device;
 struct tinydrm_device;
 struct drm_clip_rect;
 struct spi_transfer;
@@ -46,8 +45,6 @@ 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,
diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index 355e9f5..1d713b3 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -202,4 +202,13 @@ of_find_backlight_by_node(struct device_node *node)
 }
 #endif
 
+#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
+struct backlight_device *backlight_get(struct device *dev);
+#else
+static inline struct backlight_device *backlight_get(struct device *dev)
+{
+	return NULL;
+}
+#endif
+
 #endif
-- 
2.7.4

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[PATCH v11 3/3] drm/tinydrm: Add devres versions of backlight_get

[Meghana Madhyastha]

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

Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
---
Changes in v11:
-None

 drivers/gpu/drm/tinydrm/mi0283qt.c  |  2 +-
 drivers/video/backlight/backlight.c | 31 +++++++++++++++++++++++++++++++
 include/linux/backlight.h           | 16 ++++++++++++++++
 3 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tinydrm/mi0283qt.c b/drivers/gpu/drm/tinydrm/mi0283qt.c
index edf9502..03fec36 100644
--- a/drivers/gpu/drm/tinydrm/mi0283qt.c
+++ b/drivers/gpu/drm/tinydrm/mi0283qt.c
@@ -190,7 +190,7 @@ static int mi0283qt_probe(struct spi_device *spi)
 	if (IS_ERR(mipi->regulator))
 		return PTR_ERR(mipi->regulator);
 
-	mipi->backlight = backlight_get(dev);
+	mipi->backlight = devm_backlight_get(dev);
 	if (IS_ERR(mipi->backlight))
 		return PTR_ERR(mipi->backlight);
 
diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index 1debb60..fff2d1a 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -618,6 +618,37 @@ struct backlight_device *backlight_get(struct device *dev)
 	return bd;
 }
 EXPORT_SYMBOL(backlight_get);
+
+static void devm_backlight_put(void *data)
+{
+	backlight_put(data);
+}
+
+/**
+ * devm_backlight_get - Resource-managed backlight_get()
+ * @dev: Device
+ *
+ * Device managed version of backlight_get(). The reference on the backlight
+ * device is automatically dropped on driver detach.
+ */
+struct backlight_device *devm_backlight_get(struct device *dev)
+{
+	struct backlight_device *bd;
+	int ret;
+
+	bd = backlight_get(dev);
+	if (!bd)
+		return NULL;
+
+	ret = devm_add_action(dev, devm_backlight_put, bd);
+	if (ret) {
+		backlight_put(bd);
+		return ERR_PTR(ret);
+	}
+
+	return bd;
+}
+EXPORT_SYMBOL(devm_backlight_get);
 #endif
 
 static void __exit backlight_class_exit(void)
diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index 1d713b3..0bfadb6 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -183,6 +183,16 @@ 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);
+}
+
 struct generic_bl_info {
 	const char *name;
 	int max_intensity;
@@ -204,11 +214,17 @@ of_find_backlight_by_node(struct device_node *node)
 
 #if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
 struct backlight_device *backlight_get(struct device *dev);
+struct backlight_device *devm_backlight_get(struct device *dev);
 #else
 static inline struct backlight_device *backlight_get(struct device *dev)
 {
 	return NULL;
 }
+
+static inline struct backlight_device *devm_backlight_get(struct device *dev)
+{
+	return NULL;
+}
 #endif
 
 #endif
-- 
2.7.4

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Re: [PATCH v11 2/3] drm/tinydrm: Move tinydrm_of_find_backlight to backlight.c

[Noralf Trønnes]

Den 12.10.2017 11.40, skrev Meghana Madhyastha:
> Rename tinydrm_of_find_backlight to backlight_get and move it
> to linux/backlight.c so that it can be used by other drivers.
>
> Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
> ---
> Changes in v11:
> -None
>
>   drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 40 --------------------------
>   drivers/gpu/drm/tinydrm/mi0283qt.c             |  3 +-
>   drivers/video/backlight/backlight.c            | 40 ++++++++++++++++++++++++++
>   include/drm/tinydrm/tinydrm-helpers.h          |  3 --
>   include/linux/backlight.h                      |  9 ++++++
>   5 files changed, 51 insertions(+), 44 deletions(-)
>
> diff --git a/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c b/drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
> index a42dee6..cb1a01a 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 7e5bb7d..edf9502 100644
> --- a/drivers/gpu/drm/tinydrm/mi0283qt.c
> +++ b/drivers/gpu/drm/tinydrm/mi0283qt.c
> @@ -12,6 +12,7 @@
>   #include <drm/tinydrm/ili9341.h>
>   #include <drm/tinydrm/mipi-dbi.h>
>   #include <drm/tinydrm/tinydrm-helpers.h>
> +#include <linux/backlight.h>
>   #include <linux/delay.h>
>   #include <linux/gpio/consumer.h>
>   #include <linux/module.h>
> @@ -189,7 +190,7 @@ 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 = backlight_get(dev);
>   	if (IS_ERR(mipi->backlight))
>   		return PTR_ERR(mipi->backlight);
>   
> diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
> index 8049e76..1debb60 100644
> --- a/drivers/video/backlight/backlight.c
> +++ b/drivers/video/backlight/backlight.c
> @@ -580,6 +580,46 @@ struct backlight_device *of_find_backlight_by_node(struct device_node *node)
>   EXPORT_SYMBOL(of_find_backlight_by_node);
>   #endif
>   
> +/**
> + * backlight_get - 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.

Since you need to respin this, add backlight_put() to this patch instead 
of the next.

> + *
> + * 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.
> + */
> +
> +#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)

This isn't necessary since this file isn't built if not enabled.
See drivers/video/backlight/Makefile:
obj-$(CONFIG_BACKLIGHT_CLASS_DEVICE)    += backlight.o

> +struct backlight_device *backlight_get(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);
> +		}
> +	}
> +
> +	return bd;
> +}
> +EXPORT_SYMBOL(backlight_get);
> +#endif
> +
>   static void __exit backlight_class_exit(void)
>   {
>   	class_destroy(backlight_class);
> diff --git a/include/drm/tinydrm/tinydrm-helpers.h b/include/drm/tinydrm/tinydrm-helpers.h
> index f54fae0..b89d8e4 100644
> --- a/include/drm/tinydrm/tinydrm-helpers.h
> +++ b/include/drm/tinydrm/tinydrm-helpers.h
> @@ -10,7 +10,6 @@
>   #ifndef __LINUX_TINYDRM_HELPERS_H
>   #define __LINUX_TINYDRM_HELPERS_H
>   
> -struct backlight_device;
>   struct tinydrm_device;
>   struct drm_clip_rect;
>   struct spi_transfer;
> @@ -46,8 +45,6 @@ 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,
> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> index 355e9f5..1d713b3 100644
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -202,4 +202,13 @@ of_find_backlight_by_node(struct device_node *node)
>   }
>   #endif
>   
> +#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
> +struct backlight_device *backlight_get(struct device *dev);
> +#else
> +static inline struct backlight_device *backlight_get(struct device *dev)
> +{
> +	return NULL;
> +}
> +#endif
> +
>   #endif

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Re: [PATCH v11 2/3] drm/tinydrm: Move tinydrm_of_find_backlight to backlight.c

[kbuild test robot]

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Hi Meghana,

[auto build test WARNING on v4.14-rc3]
[also build test WARNING on next-20171009]
[cannot apply to drm/drm-next backlight/for-backlight-next drm-exynos/exynos-drm/for-next]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Meghana-Madhyastha/Move-backlight-helper-functions-from-tinydrm-helpers-to-linux-backlight/20171013-062032
config: i386-randconfig-x001-201741 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All warnings (new ones prefixed by >>):

   drivers/video/backlight/backlight.c: In function 'backlight_get':
>> drivers/video/backlight/backlight.c:609:39: warning: character constant too long for its type
      np = of_parse_phandle(dev->of_node, 'backlight', 0);
                                          ^~~~~~~~~~~
>> drivers/video/backlight/backlight.c:609:39: warning: passing argument 2 of 'of_parse_phandle' makes pointer from integer without a cast [-Wint-conversion]
   In file included from include/linux/irqdomain.h:34:0,
                    from include/linux/i2c.h:34,
                    from include/uapi/linux/fb.h:5,
                    from include/linux/fb.h:5,
                    from include/linux/backlight.h:12,
                    from drivers/video/backlight/backlight.c:13:
   include/linux/of.h:358:28: note: expected 'const char *' but argument is of type 'int'
    extern struct device_node *of_parse_phandle(const struct device_node *np,
                               ^~~~~~~~~~~~~~~~

vim +609 drivers/video/backlight/backlight.c

   582	
   583	/**
   584	 * backlight_get - Get backlight device
   585	 * @dev: Device
   586	 *
   587	 * This function looks for a property named 'backlight' on the DT node
   588	 * connected to @dev and looks up the backlight device.
   589	 *
   590	 * Call backlight_put() to drop the reference on the backlight device.
   591	 *
   592	 * Returns:
   593	 * A pointer to the backlight device if found.
   594	 * Error pointer -EPROBE_DEFER if the DT property is set, but no backlight
   595	 * device is found.
   596	 * NULL if there's no backlight property.
   597	 */
   598	
   599	#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
   600	struct backlight_device *backlight_get(struct device *dev)
   601	{
   602		struct backlight_device *bd = NULL;
   603		struct device_node *np;
   604	
   605		if (!dev)
   606			return NULL;
   607	
   608		if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
 > 609			np = of_parse_phandle(dev->of_node, 'backlight', 0);
   610			if (np) {
   611				bd = of_find_backlight_by_node(np);
   612				of_node_put(np);
   613				if (!bd)
   614					return ERR_PTR(-EPROBE_DEFER);
   615			}
   616		}
   617	
   618		return bd;
   619	}
   620	EXPORT_SYMBOL(backlight_get);
   621	#endif
   622	

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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