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

[Brandon Ross Pollack]

On Thu, Apr 27, 2023 at 7:02 PM Daniel Vetter <daniel at ffwll.ch> wrote:
>
> 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

I'm actually working in relative isolation on this (I'm located in
Tokyo) so please go ahead.  I'll get in touch with some of those folks
soon :)

>
> > ---
> >  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