[Intel-gfx] [PATCH v2 1/6] drm: Include the encoder itself in possible_clones

[Daniel Vetter]

On Fri, Feb 07, 2020 at 06:34:47PM +0200, Ville Syrjälä wrote:
> On Fri, Feb 07, 2020 at 05:27:51PM +0100, Daniel Vetter wrote:
> > On Fri, Feb 07, 2020 at 04:50:01PM +0200, Ville Syrjälä wrote:
> > > On Fri, Feb 07, 2020 at 03:28:35PM +0100, Thomas Zimmermann wrote:
> > > > Hi
> > > > 
> > > > Am 07.02.20 um 14:59 schrieb Ville Syrjala:
> > > > > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > > > 
> > > > > The docs say possible_clones should always include the encoder itself.
> > > > > Since most drivers don't want to deal with the complexities of cloning
> > > > > let's allow them to set possible_clones=0 and instead we'll fix that
> > > > > up in the core.
> > > > > 
> > > > > We can't put this special case into drm_encoder_init() because drivers
> > > > > will have to fill up possible_clones after adding all the relevant
> > > > > encoders. Otherwise they wouldn't know the proper encoder indexes to
> > > > > use. So we'll just do it just before registering the encoders.
> > > > > 
> > > > > TODO: Should we do something similar for possible_crtcs==0?
> > > > > 
> > > > > Cc: Thomas Zimmermann <tzimmermann at suse.de>
> > > > > Cc: Daniel Vetter <daniel at ffwll.ch>
> > > > > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > > 
> > > > May this fixup function should warn iff possible_clones was set to non-0
> > > > by the driver, but the encoder itself is missing.
> > > 
> > > Yeah, I guess we could do that.
> > 
> > +1 on that, should catch some bugs at least.
> > 
> > Also can you pls fix up the kerneldoc for drm_encoder.possible_clones,
> > defacto this now means that 0 is a totally fine setting.
> 
> Sure.
> 
> And for possible_crtcs I was thinking similar concept:
> 
> for_each_encoder()
> 	if (possible_crtc == 0)
> 		possible_crtcs = all_crtc_mask;

A quick grep shows that I think we can risk enforcing this. If that turns
out to be a misconception we can always go back to the fixup approach if
possible_crtcs is 0. But unlike possible_clones I think for possible_crtcs
the fixup-less approach looks possible at least.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch