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

[Daniel Vetter]

On Fri, Feb 07, 2020 at 03:59:50PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at 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 at suse.de>
> Cc: Daniel Vetter <daniel at ffwll.ch>
> Signed-off-by: Ville Syrjälä <ville.syrjala at 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).

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