[PATCH v8 0/3] Move backlight helper functions from tinydrm-helpers to linux/backlight

[PATCH v8 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 v8:
-Move backlight_enable and backlight_disable to linux/backlight.h 
 as static inline functions.
-Move drm_of_find_backlight to backlight.c and rename it to
backlight_get.

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             |  3 +-
 drivers/video/backlight/backlight.c            | 71 +++++++++++++++++++
 include/drm/tinydrm/tinydrm-helpers.h          |  5 --
 include/linux/backlight.h                      | 55 +++++++++++++++
 6 files changed, 130 insertions(+), 102 deletions(-)

-- 
2.7.4

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[PATCH v8 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 v8:
-This patch was not present in the earlier versions.

 drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 55 --------------------------
 drivers/gpu/drm/tinydrm/mipi-dbi.c             |  3 +-
 include/drm/tinydrm/tinydrm-helpers.h          |  2 -
 include/linux/backlight.h                      | 30 ++++++++++++++
 4 files changed, 32 insertions(+), 58 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..46f0e80 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);
+	enable_backlight(mipi->backlight);
 }
 EXPORT_SYMBOL(mipi_dbi_pipe_enable);
 
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 v8 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 v8:
-Changed the name of the tinydrm_of_find_backlight to backlight_get and moved it to
 backlight.c

 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 v8 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 v8:
-Put the devres version to backlight.c along with backlight_get.

 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..9b24dc2 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_get_release(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_get_release, 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 v8 3/3] drm/tinydrm: Add devres versions of backlight_get

[Jani Nikula]

On Wed, 11 Oct 2017, Meghana Madhyastha <meghana.madhyastha@gmail.com> wrote:
> 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 v8:
> -Put the devres version to backlight.c along with backlight_get.
>
>  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..9b24dc2 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_get_release(void *data)

I think that's a confusing name because of the "get", maybe just call it
devm_backlight_put?


BR,
Jani.



> +{
> +	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_get_release, 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

-- 
Jani Nikula, Intel Open Source Technology Center
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Re: [PATCH v8 3/3] drm/tinydrm: Add devres versions of backlight_get

[Meghana Madhyastha]

On Wed, Oct 11, 2017 at 04:56:25PM +0300, Jani Nikula wrote:
> On Wed, 11 Oct 2017, Meghana Madhyastha <meghana.madhyastha@gmail.com> wrote:
> > 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 v8:
> > -Put the devres version to backlight.c along with backlight_get.
> >
> >  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..9b24dc2 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_get_release(void *data)
> 
> I think that's a confusing name because of the "get", maybe just call it
> devm_backlight_put?

backlight_put is already in use as a helper function so wouldn't
devm_backlight_put be confusing as there is already a backlight_put?

Regards,
Meghana
 
> BR,
> Jani.
> 
> 
> 
> > +{
> > +	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_get_release, 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
> 
> -- 
> Jani Nikula, Intel Open Source Technology Center
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Re: [PATCH v8 3/3] drm/tinydrm: Add devres versions of backlight_get

[Jani Nikula]

On Wed, 11 Oct 2017, Meghana Madhyastha <meghana.madhyastha@gmail.com> wrote:
> On Wed, Oct 11, 2017 at 04:56:25PM +0300, Jani Nikula wrote:
>> On Wed, 11 Oct 2017, Meghana Madhyastha <meghana.madhyastha@gmail.com> wrote:
>> > 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 v8:
>> > -Put the devres version to backlight.c along with backlight_get.
>> >
>> >  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..9b24dc2 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_get_release(void *data)
>> 
>> I think that's a confusing name because of the "get", maybe just call it
>> devm_backlight_put?
>
> backlight_put is already in use as a helper function so wouldn't
> devm_backlight_put be confusing as there is already a backlight_put?

I'd think not, as it literally is a devm version of the same thing.

BR,
Jani.



>
> Regards,
> Meghana
>  
>> BR,
>> Jani.
>> 
>> 
>> 
>> > +{
>> > +	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_get_release, 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
>> 
>> -- 
>> Jani Nikula, Intel Open Source Technology Center

-- 
Jani Nikula, Intel Open Source Technology Center
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