[PATCH] drm/doc: Improve docs for conn_state->best_encoder

[Daniel Vetter]

On Mon, May 06, 2019 at 05:57:53PM +0300, Laurent Pinchart wrote:
> Hi Daniel,
> 
> Thank you for the patch.
> 
> On Mon, May 06, 2019 at 04:46:29PM +0200, Daniel Vetter wrote:
> > It's mandatory and considered core state since ioctls rely on this
> > working.
> > 
> > Thanks to Laurent for pointing out this gap.
> > 
> > v2: Clarify to "atomic drivers" only.
> > 
> > Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > Cc: Sean Paul <sean at poorly.run>
> > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> > ---
> >  include/drm/drm_connector.h | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> > index 02a131202add..f43f40d5888a 100644
> > --- a/include/drm/drm_connector.h
> > +++ b/include/drm/drm_connector.h
> > @@ -517,6 +517,10 @@ struct drm_connector_state {
> >  	 * Used by the atomic helpers to select the encoder, through the
> >  	 * &drm_connector_helper_funcs.atomic_best_encoder or
> >  	 * &drm_connector_helper_funcs.best_encoder callbacks.
> 
> How about updating this part as well ?
> 
> "Used by both the DRM core and the atomic helpers to select the encoder
> (through the &drm_connector_helper_funcs.atomic_best_encoder), access it
> and report it to userspace (through the GETCONNECTOR and GETENCODER
> ioctls). This field shall be set by all atomic drivers, either directly
> or through atomic helpers."

It's kinda two things, I think best to describe in two paragraphs. But I
can move the core usage up, since arguable more important. Otoh most
drivers won't care since helpers handle this, and they care more about how
@best_encoder is used.

E.g. core never calls the helper callbacks
@atomic_best_endoer/best_encoder, which isn't clear anymore with your
wording. And I have a sticker for core/helper splits :-)
-Daniel
> 
> > +	 *
> > +	 * NOTE: Atomic drivers must fill this out (either themselves or through
> > +	 * helpers), for otherwise the GETCONNECTOR and GETENCODER IOCTLs will
> > +	 * not return correct data to userspace.
> >  	 */
> >  	struct drm_encoder *best_encoder;
> >  
> 
> -- 
> Regards,
> 
> Laurent Pinchart

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