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

["Sharma, Shashank" <shashank.sharma@intel.com>]

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@intel.com> 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@intel.com>
>> Signed-off-by: Kausal Malladi <kausalmalladi@gmail.com>
>> ---
>>   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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