[Intel-gfx] [PATCH 06/18] drm/i915/display13: Only enable legacy gamma for now

[Lucas De Marchi]

On Thu, Jan 28, 2021 at 11:24:01AM -0800, Matt Roper wrote:
>The multi-segment gamma used on past platforms is gone and replaced by a
>logarithmic LUT.  Until logarithmic LUT is enabled, let's just turn off
>uapi color management (aside from legacy gamma) since it doesn't really
>make sense to expose the full degamma and CTM when we only have limited
>legacy gamma support to go with them.  Note that the hardware
>programming of the degamma and CTM is unchanged except that the degamma
>table now has 128 entries instead of just 33.
>
>The output CSC used implicitly for RGB->YUV conversions is also
>unchanged and will continue to function as expected.
>
>Cc: Lucas De Marchi <lucas.demarchi at intel.com>
>Signed-off-by: Matt Roper <matthew.d.roper at intel.com>


Reviewed-by: Lucas De Marchi <lucas.demarchi at intel.com>

Lucas De Marchi

>---
> drivers/gpu/drm/i915/i915_pci.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c
>index e5e10484bf8d..fb28f3b24dd8 100644
>--- a/drivers/gpu/drm/i915/i915_pci.c
>+++ b/drivers/gpu/drm/i915/i915_pci.c
>@@ -945,7 +945,18 @@ static const struct intel_device_info adl_s_info = {
> 		BIT(TRANSCODER_C) | BIT(TRANSCODER_D),			\
> 	.ddb_size = 4096,						\
> 	.mbus_size = 2048,						\
>-	.num_supported_dbuf_slices = 4,
>+	.num_supported_dbuf_slices = 4,					\
>+	/*								\
>+	 * FIXME: Just enable legacy gamma (and no degamma/csc) until	\
>+	 * logarithmic LUT is implemented.				\
>+	 *								\
>+	 * LEGACY_LUT_LENGTH = 256 entries				\
>+	 *								\
>+	 * Note that once logarithmic LUT is enabled and we re-enable	\
>+	 * real color management, degamma_lut_size here should be set	\
>+	 * to 128.							\
>+	 */								\
>+	.color = { .degamma_lut_size = 0, .gamma_lut_size = 256 }
>
> #undef GEN
> #undef PLATFORM
>-- 
>2.25.4
>
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