Re: [PATCH v8 3/3] drm/tinydrm: Add devres versions of backlight_get

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