[PATCH] Documentation: vkms: clarify devres managed refernce cleanup

[Daniel Vetter]

On Tue, Apr 25, 2023 at 08:02:40AM +0000, Brandon Pollack wrote:
> added documentation to drm_dev_unregister clarifying that devres managed
> devices allocated with devm_drm_dev_alloc do not require calls to
> drm_dev_put.
> 
> Signed-off-by: Brandon Pollack <brpol at chromium.org>
> 
> ---
> 
> This is my first patch to any tree.  I've tried my best to read as many
> kernel docs etc as possible (wip). This took me a moment to realize so I
> figured it was as good a candidate as any for a first patch (at the very
> least to make sure I have the whole patching process figured out).  I
> hope to make more janitorial changes as I continue to learn leading up
> to the work I hope to do.
> 
> We're hoping to add multiple display hotplug output support to VKMS for
> testing purposes.  Some work has been done already, but we'll be taking
> over moving forward.  Our intent is to remain involved and assist in
> maintaining these changes.
> 
> Looking forward to your comments/advice (now and henceforth!)

Looking good!

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

Since you're @chromium.org I'm assuming that one of the cros committers
will push this to drm-misc-next. If not please holler.
-Daniel

> ---
>  drivers/gpu/drm/drm_drv.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index cee0cc522ed9..12687dd9e1ac 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -969,7 +969,9 @@ EXPORT_SYMBOL(drm_dev_register);
>   *
>   * Unregister the DRM device from the system. This does the reverse of
>   * drm_dev_register() but does not deallocate the device. The caller must call
> - * drm_dev_put() to drop their final reference.
> + * drm_dev_put() to drop their final reference, unless it is managed with devres
> + * (as devices allocated with devm_drm_dev_alloc() are), in which case there is
> + * already an unwind action registered.
>   *
>   * A special form of unregistering for hotpluggable devices is drm_dev_unplug(),
>   * which can be called while there are still open users of @dev.
> -- 
> 2.40.0.634.g4ca3ef3211-goog
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch