Re: [Intel-gfx] [PATCH v2 6/6] drm: Validate encoder->possible_crtcs

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Feb 07, 2020 at 05:39:26PM +0100, Daniel Vetter wrote:
> On Fri, Feb 07, 2020 at 03:59:50PM +0200, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > WARN if the encoder possible_crtcs is effectively empty or contains
> > bits for non-existing crtcs.
> > 
> > TODO: Or should we perhapst just filter out any bit for a
> > non-exisiting crtc?
> > 
> > Cc: Thomas Zimmermann <tzimmermann@suse.de>
> > Cc: Daniel Vetter <daniel@ffwll.ch>
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> >From a quick grep it looks like at least most drivers seem to get this
> right. Worth a shot to find the hold-outs.
> 
> Two things:
> - Imo also best to move into the drm_mode_config_validate I suggested.
> - Please update the kerneldoc for drm_encoder.possible_crtcs to mention
>   that this will WARN if you get it wrong (and maybe remove the line that
>   most drivers screw this up).

ack

> 
> Check itself lgtm.
> -Daniel
> 
> > ---
> >  drivers/gpu/drm/drm_encoder.c | 18 ++++++++++++++++++
> >  1 file changed, 18 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_encoder.c b/drivers/gpu/drm/drm_encoder.c
> > index bc2246f27e0d..f16b2a2518d7 100644
> > --- a/drivers/gpu/drm/drm_encoder.c
> > +++ b/drivers/gpu/drm/drm_encoder.c
> > @@ -107,6 +107,23 @@ static void validate_possible_clones(struct drm_encoder *encoder)
> >  	     encoder->possible_clones, encoder_mask);
> >  }
> >  
> > +static void validate_possible_crtcs(struct drm_encoder *encoder)
> > +{
> > +	struct drm_device *dev = encoder->dev;
> > +	struct drm_crtc *crtc;
> > +	u32 crtc_mask = 0;
> > +
> > +	drm_for_each_crtc(crtc, dev)
> > +		crtc_mask |= drm_crtc_mask(crtc);
> > +
> > +	WARN((encoder->possible_crtcs & crtc_mask) == 0 ||
> > +	     (encoder->possible_crtcs & ~crtc_mask) != 0,
> > +	     "Bogus possible_crtcs: "
> > +	     "[ENCODER:%d:%s] possible_crtcs=0x%x (full crtc mask=0x%x)\n",
> > +	     encoder->base.id, encoder->name,
> > +	     encoder->possible_crtcs, crtc_mask);
> > +}
> > +
> >  int drm_encoder_register_all(struct drm_device *dev)
> >  {
> >  	struct drm_encoder *encoder;
> > @@ -115,6 +132,7 @@ int drm_encoder_register_all(struct drm_device *dev)
> >  	fixup_possible_clones(dev);
> >  
> >  	drm_for_each_encoder(encoder, dev) {
> > +		validate_possible_crtcs(encoder);
> >  		validate_possible_clones(encoder);
> >  
> >  		if (encoder->funcs->late_register)
> > -- 
> > 2.24.1
> > 
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Ville Syrjälä
Intel
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