Hi,
On Thu, Jan 16, 2025 at 02:43:37AM +0200, Dmitry Baryshkov wrote:
> On Wed, Jan 15, 2025 at 10:05:30PM +0100, Maxime Ripard wrote:
> > The current bridge state is accessible from the drm_bridge structure,
> > but since it's fairly indirect it's not easy to figure out.
> >
> > Provide a helper to retrieve it.
> >
> > Signed-off-by: Maxime Ripard <mripard@xxxxxxxxxx>
> > ---
> > include/drm/drm_bridge.h | 17 +++++++++++++++++
> > 1 file changed, 17 insertions(+)
> >
> > diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
> > index 8e18130be8bb85fc2463917dde9bf1d281934184..95c5037a6335e4c1be511e6c31308202015c7754 100644
> > --- a/include/drm/drm_bridge.h
> > +++ b/include/drm/drm_bridge.h
> > @@ -955,10 +955,27 @@ static inline struct drm_bridge *of_drm_find_bridge(struct device_node *np)
> > {
> > return NULL;
> > }
> > #endif
> >
> > +/**
> > + * @drm_bridge_get_current_state() - Get the current bridge state
> > + * @bridge: bridge object
> > + *
> > + * RETURNS:
> > + *
> > + * The current bridge state, or NULL if there is none.
>
> Are there any kind of limitations on when and how this function can be
> used? I don't think we can be accessing the state randomly, as the
> framework can change it at some points. E.g. what if the driver uses
> this state from audio or cec callbacks, while the DRM framework performs
> atomic commit and changes / frees the state right concurrently?
The semantics are equivalent to drm_connector->state, drm_crtc->state,
etc, but I'm not sure we ever defined it clearly.
Also, it looks like I can never remember what the locking rules are :)
It looks like a good occasion to ask Sima and write some more
documentation.
Thanks!
Maxime
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