[Intel-gfx] [PATCH 1/3] drm/i915: DRM_FORMAT_C8 is not possible with Yf tiling

[Ville Syrjälä]

On Mon, Sep 24, 2018 at 05:19:11PM -0700, Paulo Zanoni wrote:
> Function intel_framebuffer_init() checks for the possibilities during
> framebuffer creation (addfb ioctl time). It is missing the fact that
> the indexed format is not supported with Yf tiling.
> 
> It is worth noticing that skl_plane_format_mod_supported() correctly
> handles for the C8/Yf combination, but this function runs during
> modeset time, so we only reject the combination later.
> 
> Ville recently proposed a new IGT test that only uses addfb to assert
> supported formats, so that IGT was failing. Add the check so we get
> green squares right from the start after Ville merges his test.

I have two of three (possibly) nicer ways to solve this:
https://patchwork.freedesktop.org/series/39700/
https://patchwork.freedesktop.org/series/39383/
https://patchwork.freedesktop.org/series/39813/

Would be nice if someone could figure out a solution (one of those or
perhaps some other solution I didn't think of) that enough people are
willing to accept.

> 
> Also drive-by fix the missing /* fall through */ in the chunk we
> modified by just turning it into a "break;" since IMHO breaks are
> easier to read than fall-throughs.
> 
> BSpec: 18565
> Testcase: igt/kms_addfb_basic/expected-formats (not merged yet)
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index eb25037d7b38..fdff1779f778 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -14473,13 +14473,19 @@ static int intel_framebuffer_init(struct intel_framebuffer *intel_fb,
>  			goto err;
>  		}
>  		/* fall through */
> -	case I915_FORMAT_MOD_Y_TILED:
>  	case I915_FORMAT_MOD_Yf_TILED:
> +		if (mode_cmd->pixel_format == DRM_FORMAT_C8) {
> +			DRM_DEBUG_KMS("Indexed format does not support Yf tiling\n");
> +			goto err;
> +		}
> +		/* fall through */
> +	case I915_FORMAT_MOD_Y_TILED:
>  		if (INTEL_GEN(dev_priv) < 9) {
>  			DRM_DEBUG_KMS("Unsupported tiling 0x%llx!\n",
>  				      mode_cmd->modifier[0]);
>  			goto err;
>  		}
> +		break;
>  	case DRM_FORMAT_MOD_LINEAR:
>  	case I915_FORMAT_MOD_X_TILED:
>  		break;
> -- 
> 2.14.4

-- 
Ville Syrjälä
Intel