[Intel-gfx] [PATCH] drm/i915: Don't test plane stride with !INTEL_DISPLAY_ENABLED

[Ville Syrjälä]

On Thu, Nov 07, 2019 at 12:37:22PM -0800, Matt Roper wrote:
> If INTEL_DISPLAY_ENABLED is false, then the modesetting resources were
> never initialized.  Userspace may still call DRM_IOCTL_MODE_CREATE_DUMB
> which will eventually lead i915_gem_dumb_create() to try to dereference
> a non-existent pipe A primary plane while figuring out a proper pitch.
> 
> We could force dumb buffer creation to fail in cases where display isn't
> enabled (since there isn't really a definition of a "suitable for
> scanout" buffer in that case), but it's easier (and probably less
> invasive to IGT tests) to just drop the attempt to align to plane max
> stride in cases where the display isn't enabled.

I just pushed my earlier patch which does it the other way around.
But yeah, we should perhaps just reject the entire thing.

> 
> Cc: Lucas De Marchi <lucas.demarchi at intel.com>
> Cc: Jani Nikula <jani.nikula at intel.com>
> Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 143a8952b736..f022a17328b0 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -229,7 +229,8 @@ i915_gem_dumb_create(struct drm_file *file,
>  	args->pitch = ALIGN(args->width * cpp, 64);
>  
>  	/* align stride to page size so that we can remap */
> -	if (args->pitch > intel_plane_fb_max_stride(to_i915(dev), format,
> +	if (INTEL_DISPLAY_ENABLED(to_i915(dev)) &&
> +	    args->pitch > intel_plane_fb_max_stride(to_i915(dev), format,
>  						    DRM_FORMAT_MOD_LINEAR))
>  		args->pitch = ALIGN(args->pitch, 4096);
>  
> -- 
> 2.21.0
> 
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-- 
Ville Syrjälä
Intel