Re: [PATCH v8 15/25] drm/i915: CHV: Pipe level degamma correction

[Lionel Landwerlin <lionel.g.landwerlin@intel.com>]

I gave a try to this patch on Braswell.
A couple of comments below.

On 03/12/15 11:36, Shashank Sharma 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@intel.com>
> Signed-off-by: Kausal Malladi <kausalmalladi@gmail.com>
> ---
>   drivers/gpu/drm/i915/i915_reg.h            |  6 ++
>   drivers/gpu/drm/i915/intel_color_manager.c | 95 ++++++++++++++++++++++++++++++
>   drivers/gpu/drm/i915/intel_color_manager.h |  5 ++
>   3 files changed, 106 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 6259537..665e23e 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -8166,4 +8166,10 @@ 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 f4334c0..aa89a55 100644
> --- a/drivers/gpu/drm/i915/intel_color_manager.c
> +++ b/drivers/gpu/drm/i915/intel_color_manager.c
> @@ -27,6 +27,95 @@
>   
>   #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, cgm_control, cgm_degamma_reg;
> +	i915_reg_t val;
> +	enum pipe pipe;
> +	struct drm_palette *degamma_data;
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	struct drm_r32g32b32 *correction_values = NULL;
> +	struct drm_crtc_state *state = crtc->state;
> +
> +	if (WARN_ON(!blob))
> +		return -EINVAL;
> +
> +	degamma_data = (struct drm_palette *)blob->data;
> +	pipe = to_intel_crtc(crtc)->pipe;
> +	num_samples = blob->length / sizeof(struct drm_r32g32b32);
> +
> +	switch (num_samples) {
> +	case GAMMA_DISABLE_VALS:
> +		/* Disable DeGamma functionality on Pipe - CGM Block */
> +		val = _MMIO(_PIPE_CGM_CONTROL(pipe));
> +		cgm_control = I915_READ(val);
> +		cgm_control &= ~CGM_DEGAMMA_EN;
> +		state->palette_before_ctm_blob = NULL;
> +
> +		I915_WRITE(val, cgm_control);
> +		DRM_DEBUG_DRIVER("DeGamma disabled on Pipe %c\n",
> +				pipe_name(pipe));
> +		break;
> +
> +	case CHV_DEGAMMA_MAX_VALS:
> +		cgm_degamma_reg = _PIPE_DEGAMMA_BASE(pipe);
> +		count = 0;
> +		correction_values = (struct drm_r32g32b32 *)&degamma_data->lut;

The line above is incorrect. This is reading from an invalid memory address.
Just use this :

correction_values = degamma_data->lut;


> +		while (count < CHV_DEGAMMA_MAX_VALS) {
> +			blue = correction_values[count].b32;
> +			green = correction_values[count].g32;
> +			red = correction_values[count].r32;
> +
> +			if (blue > CHV_MAX_GAMMA)
> +				blue = CHV_MAX_GAMMA;
> +
> +			if (green > CHV_MAX_GAMMA)
> +				green = CHV_MAX_GAMMA;
> +
> +			if (red > CHV_MAX_GAMMA)
> +				red = CHV_MAX_GAMMA;
> +
> +			blue_fract = GET_BITS(blue, 8, 14);
> +			green_fract = GET_BITS(green, 8, 14);
> +			red_fract = GET_BITS(red, 8, 14);
This is reading the wrong bits from the blob here.
Using your macro, it should be :

blue_fract = GET_BITS(blue, 10, 14);
green_fract = GET_BITS(green, 10, 14);
red_fract = GET_BITS(red, 10, 14);

> +
> +			/* Green (29:16) and Blue (13:0) in DWORD1 */
> +			SET_BITS(word, green_fract, 16, 14);
> +			SET_BITS(word, blue_fract, 0, 14);
> +			val = _MMIO(cgm_degamma_reg);
> +			I915_WRITE(val, word);
> +			cgm_degamma_reg += 4;
> +
> +			/* Red (13:0) to be written to DWORD2 */
> +			word = red_fract;
> +			val = _MMIO(cgm_degamma_reg);
> +			I915_WRITE(val, word);
> +			cgm_degamma_reg += 4;
> +			count++;
> +		}
> +
> +		DRM_DEBUG_DRIVER("DeGamma LUT loaded for Pipe %c\n",
> +				pipe_name(pipe));
> +
> +		/* Enable DeGamma on Pipe */
> +		val = _MMIO(_PIPE_CGM_CONTROL(pipe));
> +		I915_WRITE(val, I915_READ(val) | CGM_DEGAMMA_EN);
> +		DRM_DEBUG_DRIVER("DeGamma correction enabled on Pipe %c\n",
> +				pipe_name(pipe));
> +		break;
> +
> +	default:
> +		DRM_ERROR("Invalid number of samples for DeGamma LUT\n");
> +		return -EINVAL;
> +	}
> +	return 0;
> +}
> +
>   static int chv_set_gamma(struct drm_device *dev, struct drm_property_blob *blob,
>   		struct drm_crtc *crtc)
>   {
> @@ -158,4 +247,10 @@ void intel_attach_color_properties_to_crtc(struct drm_device *dev,
>   		DRM_DEBUG_DRIVER("gamma property attached to CRTC\n");
>   	}
>   
> +	/* Degamma correction */
> +	if (config->cm_palette_before_ctm_property) {
> +		drm_object_attach_property(mode_obj,
> +			config->cm_palette_before_ctm_property, 0);
> +		DRM_DEBUG_DRIVER("degamma property attached to CRTC\n");
> +	}
>   }
> diff --git a/drivers/gpu/drm/i915/intel_color_manager.h b/drivers/gpu/drm/i915/intel_color_manager.h
> index de706d9..77a2119 100644
> --- a/drivers/gpu/drm/i915/intel_color_manager.h
> +++ b/drivers/gpu/drm/i915/intel_color_manager.h
> @@ -63,5 +63,10 @@
>   #define CHV_GAMMA_SHIFT_GREEN                  16
>   #define CHV_MAX_GAMMA                          ((1 << 24) - 1)
>   
> +/* Degamma on CHV */
> +#define CHV_DEGAMMA_MSB_SHIFT                  2
> +#define CHV_DEGAMMA_GREEN_SHIFT                16
> +
>   /* CHV CGM Block */
>   #define CGM_GAMMA_EN                           (1 << 2)
> +#define CGM_DEGAMMA_EN                         (1 << 0)

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