[PATCH 5/6] drm/i915: Add format modifiers for Intel

[Daniel Stone]

Hi Ben,

On 26 July 2017 at 19:08, Ben Widawsky <ben at bwidawsk.net> wrote:
> +static bool intel_primary_plane_format_mod_supported(struct drm_plane *plane,
> +                                                    uint32_t format,
> +                                                    uint64_t modifier)
> +{
> +       struct drm_i915_private *dev_priv = to_i915(plane->dev);
> +
> +       if (WARN_ON(modifier == DRM_FORMAT_MOD_INVALID))
> +               return false;
> +
> +       if (!(modifier & DRM_FORMAT_MOD_VENDOR_INTEL) &&
> +           modifier != DRM_FORMAT_MOD_LINEAR)
> +               return false;

The vendor ID isn't shifted yet, so this comparison is wrong. Even if
it was shifted, they're sequential rather than bitmask, so
NV/QCOM/BROADCOM all match (vendor & INTEL). To fix both of these:
-       if (!(modifier & DRM_FORMAT_MOD_VENDOR_INTEL) &&
-           modifier != DRM_FORMAT_MOD_LINEAR)
+       if ((modifier >> 56) != DRM_FORMAT_MOD_VENDOR_INTEL &&
+           modifier != DRM_FORMAT_MOD_LINEAR)

The practical effect is that this knocked out MOD_Y_TILED and
MOD_Y_TILED_CCS from the list, since they're the only two Intel
modifiers without the low bit set.

Cheers,
Daniel