Re: [PATCH v2 1/6] drm: Include the encoder itself in possible_clones

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Thomas Zimmermann <tzimmermann@suse.de>
Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v2 1/6] drm: Include the encoder itself in possible_clones
Date: Fri, 7 Feb 2020 16:50:01 +0200	[thread overview]
Message-ID: <20200207145001.GI13686@intel.com> (raw)
In-Reply-To: <d58f13cf-6c9e-9a1c-5cbd-e51e1ad04e80@suse.de>

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@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@suse.de>
> > Cc: Daniel Vetter <daniel@ffwll.ch>
> > Signed-off-by: Ville Syrjälä <ville.syrjala@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.

> In any case
> 
> Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
> 
> > ---
> >  drivers/gpu/drm/drm_encoder.c | 15 +++++++++++++++
> >  1 file changed, 15 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_encoder.c b/drivers/gpu/drm/drm_encoder.c
> > index e555281f43d4..f761d9306028 100644
> > --- a/drivers/gpu/drm/drm_encoder.c
> > +++ b/drivers/gpu/drm/drm_encoder.c
> > @@ -66,11 +66,26 @@ static const struct drm_prop_enum_list drm_encoder_enum_list[] = {
> >  	{ DRM_MODE_ENCODER_DPI, "DPI" },
> >  };
> >  
> > +/*
> > + * For some reason we want the encoder itself included in
> > + * possible_clones. Make life easy for drivers by allowing them
> > + * to leave possible_clones unset if no cloning is possible.
> > + */
> > +static void fixup_possible_clones(struct drm_device *dev)
> > +{
> > +	struct drm_encoder *encoder;
> > +
> > +	drm_for_each_encoder(encoder, dev)
> > +		encoder->possible_clones |= drm_encoder_mask(encoder);
> > +}
> > +
> >  int drm_encoder_register_all(struct drm_device *dev)
> >  {
> >  	struct drm_encoder *encoder;
> >  	int ret = 0;
> >  
> > +	fixup_possible_clones(dev);
> > +
> >  	drm_for_each_encoder(encoder, dev) {
> >  		if (encoder->funcs->late_register)
> >  			ret = encoder->funcs->late_register(encoder);
> > 
> 
> -- 
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Felix Imendörffer
> 

-- 
Ville Syrjälä
Intel
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