[PATCH v2 5/6] drm: Validate encoder->possible_clones

[Thomas Zimmermann]

Am 07.02.20 um 14:59 schrieb Ville Syrjala:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Many drivers are populating encoder->possible_clones wrong. Let's
> persuade them to get it right by adding some loud WARNs.
> 
> We'll cross check the bits between any two encoders. So either
> both encoders can clone with the other, or neither can.
> 
> We'll also complain about effectively empty possible_clones, and
> possible_clones containing bits for encoders that don't exist.
> 
> TODO: Or should we just silently filter out any bits for non-existing
> encoders?

Please be noisy. Setting these masks incorrectly could be a bug.

> 
> v2: encoder->possible_clones now includes the encoder itelf
> 
> 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>

Acked-by: Thomas Zimmermann <tzimmermann at suse.de>

> ---
>  drivers/gpu/drm/drm_encoder.c | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_encoder.c b/drivers/gpu/drm/drm_encoder.c
> index f761d9306028..bc2246f27e0d 100644
> --- a/drivers/gpu/drm/drm_encoder.c
> +++ b/drivers/gpu/drm/drm_encoder.c
> @@ -79,6 +79,34 @@ static void fixup_possible_clones(struct drm_device *dev)
>  		encoder->possible_clones |= drm_encoder_mask(encoder);
>  }
>  
> +static void validate_possible_clones(struct drm_encoder *encoder)
> +{
> +	struct drm_device *dev = encoder->dev;
> +	struct drm_encoder *other;
> +	u32 encoder_mask = 0;
> +
> +	drm_for_each_encoder(other, dev) {
> +		encoder_mask |= drm_encoder_mask(other);
> +
> +		WARN(!(encoder->possible_clones & drm_encoder_mask(other)) !=
> +		     !(other->possible_clones & drm_encoder_mask(encoder)),
> +		     "possible_clones mismatch: "
> +		     "[ENCODER:%d:%s] mask=0x%x possible_clones=0x%x vs. "
> +		     "[ENCODER:%d:%s] mask=0x%x possible_clones=0x%x\n",
> +		     encoder->base.id, encoder->name,
> +		     drm_encoder_mask(encoder), encoder->possible_clones,
> +		     other->base.id, other->name,
> +		     drm_encoder_mask(other), other->possible_clones);
> +	}
> +
> +	WARN((encoder->possible_clones & drm_encoder_mask(encoder)) == 0 ||
> +	     (encoder->possible_clones & ~encoder_mask) != 0,
> +	     "Bogus possible_clones: "
> +	     "[ENCODER:%d:%s] possible_clones=0x%x (full encoder mask=0x%x)\n",
> +	     encoder->base.id, encoder->name,
> +	     encoder->possible_clones, encoder_mask);
> +}
> +
>  int drm_encoder_register_all(struct drm_device *dev)
>  {
>  	struct drm_encoder *encoder;
> @@ -87,6 +115,8 @@ int drm_encoder_register_all(struct drm_device *dev)
>  	fixup_possible_clones(dev);
>  
>  	drm_for_each_encoder(encoder, dev) {
> +		validate_possible_clones(encoder);
> +
>  		if (encoder->funcs->late_register)
>  			ret = encoder->funcs->late_register(encoder);
>  		if (ret)
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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