Den 29.09.2017 05.17, skrev Meghana Madhyastha:
On Thu, Sep 28, 2017 at 06:19:35PM +0200, Noralf Trønnes wrote:
Den 28.09.2017 11.15, skrev Meghana Madhyastha:
Add devm_drm_of_find_backlight and the corresponding release
function because some drivers such as tinydrm use devres versions
of functions for requiring device resources.
Signed-off-by: Meghana Madhyastha <meghana.madhyastha@xxxxxxxxx>
---
Changes in v3:
-None
drivers/gpu/drm/drm_of.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
include/drm/drm_of.h | 2 ++
2 files changed, 50 insertions(+)
diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
index d878d3a..238e8e5 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -304,3 +304,51 @@ struct backlight_device *drm_of_find_backlight(struct device *dev)
return backlight;
}
EXPORT_SYMBOL(drm_of_find_backlight);
+
+/**
+ * devm_drm_of_find_backlight_release - Release backlight device
+ * @dev: Device
+ *
+ * This is the release function corresponding to the devm_drm_of_find_backlight.
+ * Each devres entry is associated with a release function.
+ */
This is an internal function so no need for docs or exporting. I know
that some devm_ functions have explicit release functions, but I don't
think this is necessary since those users can just use
drm_of_find_backlight() directly instead.
I have a question here. devm_drm_of_find_backlight_release is a
wrapper around put_device which is passed as a parameter to
devm_add_action in devm_drm_of_find_backlight. So isn't the function
useful here ?
We need the function for devm_add_action(), but no one outside of this
file needs
it. Hence the static definition.
We can't use put_device directly:
ret = devm_add_action(dev, put_device,
&backlight->dev);
because devm_add_action expects an argument like this: void
(*action)(void *)
and put_device is: void put_device(struct device *dev)
They differ in their argument type: void * vs. struct device *
The compiler would complain.
So we need a wrapper.
+static void devm_drm_of_find_backlight_release(void *data)
+{
+ put_device(data);
+}
+EXPORT_SYMBOL(devm_drm_of_find_backlight_release);
+
+/**
+ * devm_drm_of_find_backlight - Find backlight device in device-tree
+ * devres version of the function
+ * @dev: Device
+ *
+ * This is the devres version of the function drm_of_find_backlight.
+ * Some drivers such as tinydrm use devres versions of functions for
No need to mention tinydrm here.
+ * requiring device resources.
+ *
+ * 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 *devm_drm_of_find_backlight(struct device *dev)
+{
+ struct backlight_device *backlight;
+ int ret;
+
+ backlight = drm_of_find_backlight(dev);
+ if (IS_ERR_OR_NULL(backlight))
+ return backlight;
+
+ ret = devm_add_action(dev, devm_drm_of_find_backlight_release,
+ &backlight->dev);
+ if (ret) {
+ put_device(&backlight->dev);
+ return ERR_PTR(ret);
+ }
+
+ return backlight;
+}
+EXPORT_SYMBOL(devm_drm_of_find_backlight);
diff --git a/include/drm/drm_of.h b/include/drm/drm_of.h
index e8fba5b..071fb3b 100644
--- a/include/drm/drm_of.h
+++ b/include/drm/drm_of.h
@@ -30,7 +30,9 @@ int drm_of_find_panel_or_bridge(const struct device_node *np,
struct drm_panel **panel,
struct drm_bridge **bridge);
struct backlight_device *drm_of_find_backlight(struct device *dev);
+struct backlight_device *devm_drm_of_find_backlight(struct device *dev);
#else
We need a dummy version of devm_drm_of_find_backlight() here that
returns NULL as in the previous patch.
+static void devm_drm_of_find_backlight_release(void *data);
And this isn't needed as explained above.
static inline uint32_t drm_of_find_possible_crtcs(struct drm_device *dev,
struct device_node *port)
{
I'd appreciate if you could also switch mi0283qt over to this helper :-)
Noralf.
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