Re: [PATCH 19/22] drm/i915: BDW: Pipe level Gamma correction

[Rob Bradford <robert.bradford@intel.com>]

On Sat, 2015-10-10 at 00:59 +0530, Shashank Sharma wrote:
> BDW/SKL/BXT platforms support various Gamma correction modes
> which are:
> 1. Legacy 8-bit mode
> 2. 10-bit Split Gamma mode
> 3. 12-bit mode
> 
> This patch does the following:
> 1. Adds the core function to program Gamma correction values
>    for BDW/SKL/BXT platforms
> 2. Adds Gamma 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            |  25 ++-
>  drivers/gpu/drm/i915/intel_color_manager.c | 248
> +++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_color_manager.h |   6 +
>  3 files changed, 277 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg.h
> b/drivers/gpu/drm/i915/i915_reg.h
> index 5825ab2..ed50f75 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -5647,11 +5647,15 @@ enum skl_disp_power_wells {
>  /* legacy palette */
>  #define _LGC_PALETTE_A           0x4a000
>  #define _LGC_PALETTE_B           0x4a800
> -#define LGC_PALETTE(pipe, i) (_PIPE(pipe, _LGC_PALETTE_A,
> _LGC_PALETTE_B) + (i) * 4)
> +#define _LGC_PALETTE_C           0x4b000
> +#define LGC_PALETTE(pipe, i) (_PIPE3(pipe, _LGC_PALETTE_A,
> _LGC_PALETTE_B, \
> +			 _LGC_PALETTE_C) + (i) * 4)
>  
>  #define _GAMMA_MODE_A		0x4a480
>  #define _GAMMA_MODE_B		0x4ac80
> -#define GAMMA_MODE(pipe) _PIPE(pipe, _GAMMA_MODE_A, _GAMMA_MODE_B)
> +#define _GAMMA_MODE_C		0x4b480
> +#define GAMMA_MODE(pipe) \
> +	_PIPE3(pipe, _GAMMA_MODE_A, _GAMMA_MODE_B, _GAMMA_MODE_C)
>  #define GAMMA_MODE_MODE_MASK	(3 << 0)
>  #define GAMMA_MODE_MODE_8BIT	(0 << 0)
>  #define GAMMA_MODE_MODE_10BIT	(1 << 0)
> @@ -8062,6 +8066,23 @@ enum skl_disp_power_wells {
>  #define _PIPE_CSC_BASE(pipe) \
>  	(_PIPE3(pipe, PIPEA_CGM_CSC, PIPEB_CGM_CSC, PIPEC_CGM_CSC))
>  
> +/* BDW gamma correction */
> +#define PAL_PREC_INDEX_A                       0x4A400
> +#define PAL_PREC_INDEX_B                       0x4AC00
> +#define PAL_PREC_INDEX_C                       0x4B400
> +#define PAL_PREC_DATA_A                        0x4A404
> +#define PAL_PREC_DATA_B                        0x4AC04
> +#define PAL_PREC_DATA_C                        0x4B404
> +#define PAL_PREC_GCMAX_A			0x4A410
> +#define PAL_PREC_GCMAX_B			0x4AC10
> +#define PAL_PREC_GCMAX_C			0x4B410
> +
> +#define _PREC_PAL_INDEX(pipe) \
> +	(_PIPE3(pipe, PAL_PREC_INDEX_A, PAL_PREC_INDEX_B,
> PAL_PREC_INDEX_C))
> +#define _PREC_PAL_DATA(pipe) \
> +	(_PIPE3(pipe, PAL_PREC_DATA_A, PAL_PREC_DATA_B,
> PAL_PREC_DATA_C))
> +#define _PREC_PAL_GCMAX(pipe) \
> +	(_PIPE3(pipe, PAL_PREC_GCMAX_A, PAL_PREC_GCMAX_B,
> PAL_PREC_GCMAX_C))
>  
>  
>  #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 d5315b2..74f8fc3 100644
> --- a/drivers/gpu/drm/i915/intel_color_manager.c
> +++ b/drivers/gpu/drm/i915/intel_color_manager.c
> @@ -26,6 +26,252 @@
>   */
>  
>  #include "intel_color_manager.h"
> +static void bdw_write_10bit_gamma_precision(struct drm_device *dev,
> +	struct drm_r32g32b32 *correction_values, u32 pal_prec_data,
> +			u32 no_of_coeff)
> +{
> +	u16 blue_fract, green_fract, red_fract;
> +	u32 word = 0;
> +	u32 count = 0;
> +	u32 blue, green, red;
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +
> +	while (count < no_of_coeff) {
> +
> +		blue = correction_values[count].b32;
> +		green = correction_values[count].g32;
> +		red = correction_values[count].r32;
> +
> +		/*
> +		* Maximum possible gamma correction value supported
> +		* for BDW is 0xFFFFFFFF, so clip the values
> accordingly
> +		*/

I think you mean clamp not clip.

> +		if (blue >= BDW_MAX_GAMMA)
> +			blue = BDW_MAX_GAMMA;
> +		if (green >= BDW_MAX_GAMMA)
> +			green = BDW_MAX_GAMMA;
> +		if (red >= BDW_MAX_GAMMA)
> +			red = BDW_MAX_GAMMA;

So this handles the issue that was raised before that 1.0 in 8.24
should map to 1023.

> +
> +		/*
> +		* Gamma correction values are sent in 8.24 format
> +		* with 8 int and 24 fraction bits. BDW 10 bit gamma
> +		* unit expects correction registers to be programmed
> in
> +		* 0.10 format, with 0 int and 16 fraction bits. So
> take
> +		* MSB 10 bit values(bits 23-14) from the fraction
> part and
> +		* prepare the correction registers.
> +		*/
> +		blue_fract = GET_BITS(blue, 14, 10);
> +		green_fract = GET_BITS(green, 14, 10);
> +		red_fract = GET_BITS(red, 14, 10);
> +

I think this should round to the nearest rather than floor.

> +		/* Arrange: Red (29:20) Green (19:10) and Blue (9:0)
> */
> +		SET_BITS(word, red_fract, 20, 10);
> +		SET_BITS(word, red_fract, 10, 10);
> +		SET_BITS(word, red_fract, 0, 10);

Red is my favourite colour too, is that why you programmed all the
channels to the red bits? :-)

> +		I915_WRITE(pal_prec_data, word);
> +		count++;
> +	}
> +	DRM_DEBUG_DRIVER("Gamma correction programmed\n");
> +}
> +
> +void bdw_write_12bit_gamma_precision(struct drm_device *dev,
> +	struct drm_r32g32b32 *correction_values, u32 pal_prec_data,
> +		enum pipe pipe)
> +{
> +	uint16_t blue_fract, green_fract, red_fract;
> +	uint32_t gcmax;
> +	uint32_t word = 0;
> +	uint32_t count = 0;
> +	uint32_t gcmax_reg;
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +
> +	/* Program first 512 values in precision palette */
> +	while (count < BDW_12BIT_GAMMA_MAX_VALS - 1) {
> +		/*
> +		* Framework's general gamma format is 8.24 (8 int 16
> fraction)
> +		* BDW Platform's supported gamma format is 16 bit
> correction
> +		* values in 0.16 format. So extract higher 16
> fraction bits
> +		* from 8.24 gamma correction values.
> +		*/
> +		red_fract = GET_BITS(correction_values[count].r32,
> 8, 16);
> +		green_fract = GET_BITS(correction_values[count].g32,
> 8, 16);
> +		blue_fract = GET_BITS(correction_values[count].b32,
> 8, 16);

Again, 1.0 in 8.24 will result in you programming zeros rather than
max.

> +		/*
> +		* From the bspec:
> +		* For 12 bit gamma correction, program precision
> palette
> +		* with 16 bits per color in a 0.16 format with 0
> integer and
> +		* 16 fractional bits (upper 10 bits in odd indexes,
> lower 6
> +		* bits in even indexes)
> +		*/
> +
> +		/* Even index: Lower 6 bits from correction should
> go as MSB */
> +		SET_BITS(word, GET_BITS(red_fract, 0, 6), 24, 6);
> +		SET_BITS(word, GET_BITS(green_fract, 0, 6), 14, 6);
> +		SET_BITS(word, GET_BITS(blue_fract, 0, 6), 4, 6);
> +		I915_WRITE(pal_prec_data, word);
> +
> +		word = 0x0;
> +		/* Odd index: Upper 10 bits of correction should go
> as MSB */
> +		SET_BITS(word, GET_BITS(red_fract, 6, 10), 20, 10);
> +		SET_BITS(word, GET_BITS(green_fract, 6, 10), 10,
> 10);
> +		SET_BITS(word, GET_BITS(blue_fract, 6, 10), 0, 10);
> +
> +		I915_WRITE(pal_prec_data, word);
> +		count++;
> +	}
> +
> +	/* Now program the 513th value in GCMAX regs */
> +	word = 0;
> +	gcmax_reg = _PREC_PAL_GCMAX(pipe);
> +	gcmax = min_t(u32, GET_BITS(correction_values[count].r32, 8,
> 17),
> +				BDW_MAX_GAMMA);
> +	SET_BITS(word, gcmax, 0, 17);
> +	I915_WRITE(gcmax_reg, word);
> +	gcmax_reg += 4;
> +
> +	word = 0;
> +	gcmax = min_t(u32, GET_BITS(correction_values[count].g32, 8,
> 17),
> +				BDW_MAX_GAMMA);
> +	SET_BITS(word, gcmax, 0, 17);
> +	I915_WRITE(gcmax_reg, word);
> +	gcmax_reg += 4;
> +
> +	word = 0;
> +	gcmax = min_t(u32, GET_BITS(correction_values[count].b32, 8,
> 17),
> +				BDW_MAX_GAMMA);
> +	SET_BITS(word, gcmax, 0, 17);
> +	I915_WRITE(gcmax_reg, word);
> +}
> +
> +/* Apply unity gamma for gamma reset */
> +static void bdw_reset_gamma(struct drm_i915_private *dev_priv,
> +			enum pipe pipe)
> +{
> +	u16 count = 0;
> +	u32 val;
> +	u32 pal_prec_data = LGC_PALETTE(pipe, 0);
> +
> +	DRM_DEBUG_DRIVER("\n");
> +
> +	/* Reset the palette for unit gamma */
> +	while (count < BDW_8BIT_GAMMA_MAX_VALS) {
> +		/* Red (23:16) Green (15:8) and Blue (7:0) */
> +		val = (count << 16) | (count << 8) | count;
> +		I915_WRITE(pal_prec_data, val);
> +		pal_prec_data += 4;
> +		count++;
> +	}
> +}
> +
> +static int bdw_set_gamma(struct drm_device *dev, struct
> drm_property_blob *blob,
> +			struct drm_crtc *crtc)
> +{
> +	u16 blue_fract, green_fract, red_fract;
> +	enum pipe pipe;
> +	int count, num_samples;
> +	u32 blue, green, red;
> +	u32 mode, pal_prec_index, pal_prec_data;
> +	u32 index;
> +	u32 word = 0;
> +	struct drm_palette *gamma_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;
> +
> +	gamma_data = (struct drm_palette *)blob->data;
> +	pipe = to_intel_crtc(crtc)->pipe;
> +	num_samples = gamma_data->num_samples;
> +
> +	pal_prec_index = _PREC_PAL_INDEX(pipe);
> +	pal_prec_data = _PREC_PAL_DATA(pipe);
> +
> +	correction_values = (struct drm_r32g32b32 *)&gamma_data
> ->lut;
> +	index = I915_READ(pal_prec_index);
> +
> +	switch (num_samples) {
> +	case GAMMA_DISABLE_VALS:
> +
> +		/* Disable Gamma functionality on Pipe */
> +		DRM_DEBUG_DRIVER("Disabling gamma on Pipe %c\n",
> +		pipe_name(pipe));
> +		mode = I915_READ(GAMMA_MODE(pipe));
> +		if ((mode & GAMMA_MODE_MODE_MASK) ==
> GAMMA_MODE_MODE_12BIT)
> +			bdw_reset_gamma(dev_priv, pipe);

Why only call bdw_reset_gamma() if we were in 12-bit mode? What about
the other modes? What about if somebody has programmed the value
through the legacy ioctl? 

> +		state->palette_after_ctm_blob = NULL;
> +		word = GAMMA_MODE_MODE_8BIT;
> +		break;
> +
> +	case BDW_8BIT_GAMMA_MAX_VALS:
> +
> +		/* Legacy palette */
> +		pal_prec_data = LGC_PALETTE(pipe, 0);
> +		count = 0;
> +		while (count < BDW_8BIT_GAMMA_MAX_VALS) {
> +			blue = correction_values[count].b32;
> +			green = correction_values[count].g32;
> +			red = correction_values[count].r32;
> +
> +			blue_fract = GET_BITS(blue, 16, 8);
> +			green_fract = GET_BITS(green, 16, 8);
> +			red_fract = GET_BITS(red, 16, 8);

Shouldn't these round? Rather than always floor. Also 1.0 in 8.24
format will result in you programming zero into the palette. You need
to do the max clamping again.

> +
> +			/* Blue (7:0) Green (15:8) and Red (23:16)
> */
> +			SET_BITS(word, blue_fract, 0, 8);
> +			SET_BITS(word, green_fract, 8, 8);
> +			SET_BITS(word, blue_fract, 16, 8);
> +			I915_WRITE(pal_prec_data, word);
> +			pal_prec_data += 4;
> +			count++;

This code also needs to be made to work nicely with other users of
LGC_PALETTE.

> +		}
> +		word = GAMMA_MODE_MODE_8BIT;
> +		break;
> +
> +	case BDW_SPLITGAMMA_MAX_VALS:
> +
> +		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);
> +		word = GAMMA_MODE_MODE_SPLIT;
> +		break;
> +
> +	case BDW_12BIT_GAMMA_MAX_VALS:
> +
> +		index |= BDW_INDEX_AUTO_INCREMENT;
> +		index &= ~BDW_INDEX_SPLIT_MODE;
> +		I915_WRITE(pal_prec_index, index);
> +		bdw_write_12bit_gamma_precision(dev,
> correction_values,
> +			pal_prec_data, pipe);
> +		word = GAMMA_MODE_MODE_12BIT;
> +		break;
> +
> +	case BDW_10BIT_GAMMA_MAX_VALS:
> +		index |= BDW_INDEX_AUTO_INCREMENT;
> +		index &= ~BDW_INDEX_SPLIT_MODE;
> +		I915_WRITE(pal_prec_index, index);
> +		bdw_write_10bit_gamma_precision(dev,
> correction_values,
> +			pal_prec_data, BDW_10BIT_GAMMA_MAX_VALS);
> +		word = GAMMA_MODE_MODE_10BIT;
> +		break;
> +
> +	default:
> +		DRM_ERROR("Invalid number of samples\n");
> +		return -EINVAL;
> +	}
> +
> +	/* Set gamma mode on pipe control reg */
> +	mode = I915_READ(GAMMA_MODE(pipe));
> +	mode &= ~GAMMA_MODE_MODE_MASK;
> +	I915_WRITE(GAMMA_MODE(pipe), mode | word);
> +	DRM_DEBUG_DRIVER("Gamma applied on pipe %c\n",
> +	pipe_name(pipe));
> +	return 0;
> +}
>  
>  static s16 chv_prepare_csc_coeff(s64 csc_value)
>  {
> @@ -319,6 +565,8 @@ void intel_color_manager_crtc_commit(struct
> drm_device *dev,
>  		/* Gamma correction is platform specific */
>  		if (IS_CHERRYVIEW(dev))
>  			ret = chv_set_gamma(dev, blob, crtc);
> +		else if (IS_BROADWELL(dev) || IS_GEN9(dev))
> +			ret = bdw_set_gamma(dev, blob, crtc);
>  
>  		if (ret)
>  			DRM_ERROR("set Gamma correction failed\n");
> diff --git a/drivers/gpu/drm/i915/intel_color_manager.h
> b/drivers/gpu/drm/i915/intel_color_manager.h
> index 271246a..6c7cb08 100644
> --- a/drivers/gpu/drm/i915/intel_color_manager.h
> +++ b/drivers/gpu/drm/i915/intel_color_manager.h
> @@ -92,3 +92,9 @@
>  
>  /* Gamma on BDW */
>  #define BDW_SPLITGAMMA_MAX_VALS                512
> +#define BDW_8BIT_GAMMA_MAX_VALS		256
> +#define BDW_10BIT_GAMMA_MAX_VALS		1024
> +#define BDW_12BIT_GAMMA_MAX_VALS		513
> +#define BDW_MAX_GAMMA                         ((1 << 24) - 1)
> +#define BDW_INDEX_AUTO_INCREMENT               (1 << 15)
> +#define BDW_INDEX_SPLIT_MODE                   (1 << 31)

Rob
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx