On Mon, 18 May 2020, Daniel Thompson <daniel.thompson@xxxxxxxxxx> wrote:
> On Sun, May 17, 2020 at 09:01:29PM +0200, Sam Ravnborg wrote:
>> Improve the documentation for backlight_device and
>> adapt it to kernel-doc style.
>>
>> Signed-off-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
>> Cc: Lee Jones <lee.jones@xxxxxxxxxx>
>> Cc: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
>> Cc: Jingoo Han <jingoohan1@xxxxxxxxx>
>> ---
>> include/linux/backlight.h | 81 ++++++++++++++++++++++++++++-----------
>> 1 file changed, 58 insertions(+), 23 deletions(-)
>>
>> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
>> index 7f9cef299d6e..e2d72936bf05 100644
>> --- a/include/linux/backlight.h
>> +++ b/include/linux/backlight.h
>> @@ -14,21 +14,6 @@
>> #include <linux/mutex.h>
>> #include <linux/notifier.h>
>>
>> -/* Notes on locking:
>> - *
>> - * backlight_device->ops_lock is an internal backlight lock protecting the
>> - * ops pointer and no code outside the core should need to touch it.
>> - *
>> - * Access to update_status() is serialised by the update_lock mutex since
>> - * most drivers seem to need this and historically get it wrong.
>> - *
>> - * Most drivers don't need locking on their get_brightness() method.
>> - * If yours does, you need to implement it in the driver. You can use the
>> - * update_lock mutex if appropriate.
>> - *
>> - * Any other use of the locks below is probably wrong.
>> - */
>> -
>> enum backlight_update_reason {
>> BACKLIGHT_UPDATE_HOTKEY,
>> BACKLIGHT_UPDATE_SYSFS,
>> @@ -221,30 +206,80 @@ struct backlight_properties {
>> enum backlight_scale scale;
>> };
>>
>> +/**
>> + * struct backlight_device - backlight device data
>> + *
>> + * This structure holds all data required by a backlight device.
>> + */
>> struct backlight_device {
>> - /* Backlight properties */
>> + /**
>> + * @props:
>> + *
>
> As last patch. Why no brief descriptions?
There are no "brief descriptions" in kernel-doc struct member inline
markup.
It would be possible to shorten this to:
/**
* @props: Backlight properties
*/
BR,
Jani.
>
>
>> + * Backlight properties
>> + */
>> struct backlight_properties props;
>>
>> - /* Serialise access to update_status method */
>> + /**
>> + * @update_lock:
>> + *
>> + * update_lock is an internal backlight lock that serialise access
>> + * to the update_status() method. The iupdate_lock mutex shall not be used
>> + * by backlight drivers.
>
> In addition to the typo this directly contradicts the advice in the
> original "Notes on locking".
>
> A change this dramatic needs to be fully explaining in the patch
> description.
>
>
> Daniel.
>
>
>> + */
>> struct mutex update_lock;
>>
>> - /* This protects the 'ops' field. If 'ops' is NULL, the driver that
>> - registered this device has been unloaded, and if class_get_devdata()
>> - points to something in the body of that driver, it is also invalid. */
>> + /**
>> + * @ops_lock:
>> + *
>> + * ops_lock is an internal backlight lock that protects the ops pointer
>> + * and is used around all accesses to ops and when the operations are
>> + * invoked. The mutex shall not be used by backlight drivers.
>> + */
>> struct mutex ops_lock;
>> +
>> + /**
>> + * @ops:
>> + *
>> + * Pointer to the backlight operations. If ops is NULL, the driver that
>> + * registered this device has been unloaded, and if class_get_devdata()
>> + * points to something in the body of that driver, it is also invalid.
>> + */
>> const struct backlight_ops *ops;
>>
>> - /* The framebuffer notifier block */
>> + /**
>> + * @fb_notif:
>> + *
>> + * The framebuffer notifier block
>> + */
>> struct notifier_block fb_notif;
>>
>> - /* list entry of all registered backlight devices */
>> + /**
>> + * @entry:
>> + *
>> + * List entry of all registered backlight devices
>> + */
>> struct list_head entry;
>>
>> + /**
>> + * @dev:
>> + *
>> + * Parent device.
>> + */
>> struct device dev;
>>
>> - /* Multiple framebuffers may share one backlight device */
>> + /**
>> + * @fb_bl_on:
>> + *
>> + * Multiple fbdev's may share one backlight device. The fb_bl_on
>> + * records the state of the individual fbdev.
>> + */
>> bool fb_bl_on[FB_MAX];
>>
>> + /**
>> + * @use_count:
>> + *
>> + * The number of uses of fb_bl_on.
>> + */
>> int use_count;
>> };
>>
>> --
>> 2.25.1
>>
--
Jani Nikula, Intel Open Source Graphics Center
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