drm: Add color management LUT validation helper (v4)
Some hardware may place additional restrictions on the gamma/degamma curves described by our LUT properties. E.g., that a gamma curve never decreases or that the red/green/blue channels of a LUT's entries must be equal. Let's add a helper function that drivers can use to test that a userspace-provided LUT is valid and doesn't violate hardware requirements. v2: - Combine into a single helper that just takes a bitmask of the tests to apply. (Brian Starkey) - Add additional check (always performed) that LUT property blob size is always a multiple of the LUT entry size. (stolen from ARM driver) v3: - Drop the LUT size check again since drm_atomic_replace_property_blob_from_id() already covers this for us. (Alexandru Gheorghe) v4: - Use an enum to describe possible test values rather than #define's; this is cleaner to provide kerneldoc for. (Daniel Vetter) - s/DRM_COLOR_LUT_INCREASING/DRM_COLOR_LUT_NON_DECREASING/. (Ville) Cc: Uma Shankar <uma.shankar@intel.com> Cc: Swati Sharma <swati2.sharma@intel.com> Cc: Brian Starkey <Brian.Starkey@arm.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Matt Roper <matthew.d.roper@intel.com> Reviewed-by: Brian Starkey <brian.starkey@arm.com> Reviewed-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe@arm.com> Reviewed-by: Uma Shankar <uma.shankar@intel.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20181217224415.12848-1-matthew.d.roper@intel.com
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