[PATCH 14/22] drm/i915: CHV: Pipe level degamma correction

[Emil Velikov]

Hi Shashank,

On 9 October 2015 at 20:29, Shashank Sharma <shashank.sharma at intel.com> wrote:
> CHV/BSW supports Degamma color correction, which linearizes all
> the non-linear color values. This will be applied before Color
> Transformation.
>
> This patch does the following:
> 1. Attach deGamma property to CRTC
> 2. Add the core function to program DeGamma correction values for
>    CHV/BSW platform
> 2. Add DeGamma correction macros/defines
>
> Signed-off-by: Shashank Sharma <shashank.sharma at intel.com>
> Signed-off-by: Kausal Malladi <kausalmalladi at gmail.com>
> ---
>  drivers/gpu/drm/i915/i915_reg.h            |  6 ++
>  drivers/gpu/drm/i915/intel_color_manager.c | 93 ++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_color_manager.h |  5 ++
>  3 files changed, 104 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 885ac8a..c32e35d 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -8050,4 +8050,10 @@ enum skl_disp_power_wells {
>  #define _PIPE_GAMMA_BASE(pipe) \
>         (_PIPE3(pipe, PIPEA_CGM_GAMMA, PIPEB_CGM_GAMMA, PIPEC_CGM_GAMMA))
>
> +#define PIPEA_CGM_DEGAMMA                      (VLV_DISPLAY_BASE + 0x66000)
> +#define PIPEB_CGM_DEGAMMA                      (VLV_DISPLAY_BASE + 0x68000)
> +#define PIPEC_CGM_DEGAMMA                      (VLV_DISPLAY_BASE + 0x6A000)
> +#define _PIPE_DEGAMMA_BASE(pipe) \
> +       (_PIPE3(pipe, PIPEA_CGM_DEGAMMA, PIPEB_CGM_DEGAMMA, PIPEC_CGM_DEGAMMA))
> +
>  #endif /* _I915_REG_H_ */
> diff --git a/drivers/gpu/drm/i915/intel_color_manager.c b/drivers/gpu/drm/i915/intel_color_manager.c
> index cf381b8..bbfe185 100644
> --- a/drivers/gpu/drm/i915/intel_color_manager.c
> +++ b/drivers/gpu/drm/i915/intel_color_manager.c
> @@ -27,6 +27,93 @@
>
>  #include "intel_color_manager.h"
>
> +static int chv_set_degamma(struct drm_device *dev,
> +       struct drm_property_blob *blob, struct drm_crtc *crtc)
> +{
> +       u16 red_fract, green_fract, blue_fract;
> +       u32 red, green, blue;
> +       u32 num_samples;
> +       u32 word = 0;
> +       u32 count = 0;
> +       u32 cgm_control_reg = 0;
> +       u32 cgm_degamma_reg = 0;
> +       int length;
> +       int ret = 0;
> +       enum pipe pipe;
> +       struct drm_palette *degamma_data;
> +       struct drm_i915_private *dev_priv = dev->dev_private;
> +       struct drm_r32g32b32 *correction_values = NULL;
Most of the above initializations can go.

> +
> +       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;
> +       length = num_samples * sizeof(struct drm_r32g32b32);
This can overflow.

> +
> +       if (num_samples == GAMMA_DISABLE_VALS) {
You've opted for switch statements in other patches. Why the if else
ladder in here ?

> +               /* Disable DeGamma functionality on Pipe - CGM Block */
> +               cgm_control_reg = I915_READ(_PIPE_CGM_CONTROL(pipe));
> +               cgm_control_reg &= ~CGM_DEGAMMA_EN;
> +               I915_WRITE(_PIPE_CGM_CONTROL(pipe), cgm_control_reg);
> +               DRM_DEBUG_DRIVER("DeGamma disabled on Pipe %c\n",
> +                               pipe_name(pipe));
> +               ret = 0;
Drop the ret variable through the function ?

> +       } else if (num_samples == CHV_DEGAMMA_MAX_VALS) {
> +               cgm_degamma_reg = _PIPE_DEGAMMA_BASE(pipe);
> +
> +               count = 0;
> +               correction_values = (struct drm_r32g32b32 *)&degamma_data->lut;
> +               while (count < CHV_DEGAMMA_MAX_VALS) {
For loop ?

Regards,
Emil