Re: [PATCH 21/22] drm/i915: BDW: Pipe level degamma correction

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Regards
Shashank

On 10/10/2015 5:19 AM, Emil Velikov wrote:
Hi Shashank,

On 9 October 2015 at 20:29, Shashank Sharma <shashank.sharma@xxxxxxxxx> wrote:
BDW/SKL/BXT supports Degamma color correction feature, which
linearizes the non-linearity due to gamma encoded color values.
This will be applied before Color Transformation.

This patch does the following:
1. Adds the core function to program DeGamma correction values for
    BDW/SKL/BXT platform
2. Adds DeGamma correction macros/defines

Signed-off-by: Shashank Sharma <shashank.sharma@xxxxxxxxx>
Signed-off-by: Kausal Malladi <kausalmalladi@xxxxxxxxx>
---
  drivers/gpu/drm/i915/intel_color_manager.c | 59 ++++++++++++++++++++++++++++++
  1 file changed, 59 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_color_manager.c b/drivers/gpu/drm/i915/intel_color_manager.c
index 74f8fc3..e659382 100644
--- a/drivers/gpu/drm/i915/intel_color_manager.c
+++ b/drivers/gpu/drm/i915/intel_color_manager.c
@@ -273,6 +273,63 @@ static int bdw_set_gamma(struct drm_device *dev, struct drm_property_blob *blob,
         return 0;
  }

+static int bdw_set_degamma(struct drm_device *dev,
+       struct drm_property_blob *blob, struct drm_crtc *crtc)
+{
+       enum pipe pipe;
+       int num_samples, length;
+       u32 index, mode;
+       u32 pal_prec_index, pal_prec_data;
+       struct drm_palette *degamma_data;
+       struct drm_crtc_state *state = crtc->state;
+       struct drm_i915_private *dev_priv = dev->dev_private;
+       struct drm_r32g32b32 *correction_values = NULL;
+
+       if (WARN_ON(!blob))
+               return -EINVAL;
+
+       degamma_data = (struct drm_palette *)blob->data;
+       pipe = to_intel_crtc(crtc)->pipe;
+       num_samples = degamma_data->num_samples;
+
+       if (num_samples == GAMMA_DISABLE_VALS) {
+               /* Disable degamma on Pipe */
+               mode = I915_READ(GAMMA_MODE(pipe)) & ~GAMMA_MODE_MODE_MASK;
+               I915_WRITE(GAMMA_MODE(pipe), mode | GAMMA_MODE_MODE_8BIT);
+
+               state->palette_before_ctm_blob = NULL;
+               DRM_DEBUG_DRIVER("Disabling degamma on Pipe %c\n",
+               pipe_name(pipe));
+               return 0;
+       }
+
+       if (num_samples != BDW_SPLITGAMMA_MAX_VALS) {
+               DRM_ERROR("Invalid number of samples\n");
+               return -EINVAL;
+       }
+
Why don't you use switch statement here ?

Same as CHV degamma. Degamma has only 3 conditions (enable/disable and invalid), and we generally try to accommodate upto 3 condition within if ... else.
+       length = num_samples * sizeof(struct drm_r32g32b32);
+       mode = I915_READ(GAMMA_MODE(pipe));
+       pal_prec_index = _PREC_PAL_INDEX(pipe);
+       pal_prec_data = _PREC_PAL_DATA(pipe);
+
+       correction_values = (struct drm_r32g32b32 *)&degamma_data->lut;
+       index = I915_READ(pal_prec_index);
+       index |= BDW_INDEX_AUTO_INCREMENT | BDW_INDEX_SPLIT_MODE;
+       I915_WRITE(pal_prec_index, index);
+
+       bdw_write_10bit_gamma_precision(dev, correction_values,
+               pal_prec_data, BDW_SPLITGAMMA_MAX_VALS);
+
+       /* Enable DeGamma on Pipe */
+       mode &= ~GAMMA_MODE_MODE_MASK;
+       I915_WRITE(GAMMA_MODE(pipe), mode | GAMMA_MODE_MODE_SPLIT);
+       DRM_DEBUG_DRIVER("DeGamma correction enabled on Pipe %c\n",
+       pipe_name(pipe));
Indentation seems funny here.

Yeah, every time time we try to publish a success story, pipe_name() ruins it :). Will fix it.
Regards,
Emil

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