Re: [i-g-t 12/14] kms_color_helper: Add helper functions to support logarithmic gamma mode

[Pekka Paalanen <ppaalanen@gmail.com>]

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On Mon, 15 Nov 2021 15:17:57 +0530
Bhanuprakash Modem <bhanuprakash.modem@intel.com> wrote:

> From: Mukunda Pramodh Kumar <mukunda.pramodh.kumar@intel.com>
> 
> Add helper functions to support logarithmic gamma mode
> 
> Cc: Harry Wentland <harry.wentland@amd.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
> Cc: Uma Shankar <uma.shankar@intel.com>
> Signed-off-by: Mukunda Pramodh Kumar <mukunda.pramodh.kumar@intel.com>
> Signed-off-by: Bhanuprakash Modem <bhanuprakash.modem@intel.com>
> ---
>  tests/kms_color_helper.c | 127 +++++++++++++++++++++++++++++++++++++++
>  tests/kms_color_helper.h |  16 +++++
>  2 files changed, 143 insertions(+)
> 
> diff --git a/tests/kms_color_helper.c b/tests/kms_color_helper.c
> index c65b7a0f50..7ea8282df3 100644
> --- a/tests/kms_color_helper.c
> +++ b/tests/kms_color_helper.c
> @@ -190,6 +190,33 @@ struct drm_color_lut *coeffs_to_lut(data_t *data,
>  	return lut;
>  }
>  
> +struct drm_color_lut *coeffs_to_logarithmic_lut(data_t *data,
> +						const gamma_lut_t *gamma,
> +						uint32_t color_depth,
> +						int off)
> +{
> +	struct drm_color_lut *lut;
> +	int i, lut_size = gamma->size;
> +	/* This is the maximum value due to 16 bit precision in hardware. */

In whose hardware?

Are igt tests not supposed to be generic for everything that exposes
the particular KMS properties?

This also hints that the UAPI design is lacking, because userspace
needs to know hardware specific things out of thin air. Display servers
are not going to have hardware-specific code. They specialise based on
the existence of KMS properties instead.

> +	uint32_t max_hw_value = (1 << 16) - 1;
> +	unsigned int max_segment_value = 1 << 24;
> +
> +	lut = malloc(sizeof(struct drm_color_lut) * lut_size);
> +
> +	for (i = 0; i < lut_size; i++) {
> +		double scaling_factor = (double)max_hw_value / (double)max_segment_value;
> +		uint32_t r = MIN((gamma->coeffs[i].r * scaling_factor), max_hw_value);
> +		uint32_t g = MIN((gamma->coeffs[i].g * scaling_factor), max_hw_value);
> +		uint32_t b = MIN((gamma->coeffs[i].b * scaling_factor), max_hw_value);
> +
> +		lut[i].red = r;
> +		lut[i].green = g;
> +		lut[i].blue = b;
> +	}
> +
> +	return lut;
> +}
> +
>  void set_degamma(data_t *data,
>  		 igt_pipe_t *pipe,
>  		 const gamma_lut_t *gamma)
> @@ -203,6 +230,15 @@ void set_degamma(data_t *data,
>  	free(lut);
>  }
>  
> +void set_pipe_gamma(igt_pipe_t *pipe,
> +		    uint64_t value,
> +		    struct drm_color_lut *lut,
> +		    uint32_t size)
> +{
> +	igt_pipe_obj_set_prop_value(pipe, IGT_CRTC_GAMMA_MODE, value);
> +	igt_pipe_obj_replace_prop_blob(pipe, IGT_CRTC_GAMMA_LUT, lut, size);
> +}
> +
>  void set_gamma(data_t *data,
>  	       igt_pipe_t *pipe, const gamma_lut_t *gamma)
>  {
> @@ -241,6 +277,51 @@ void disable_prop(igt_pipe_t *pipe, enum igt_atomic_crtc_properties prop)
>  		igt_pipe_obj_replace_prop_blob(pipe, prop, NULL, 0);
>  }
>  
> +drmModePropertyPtr get_pipe_gamma_degamma_mode(igt_pipe_t *pipe,
> +					       enum igt_atomic_crtc_properties prop)
> +{
> +	igt_display_t *display = pipe->display;
> +	uint32_t prop_id = pipe->props[prop];
> +	drmModePropertyPtr drmProp;
> +
> +	igt_assert(prop_id);
> +
> +	drmProp = drmModeGetProperty(display->drm_fd, prop_id);
> +
> +	igt_assert(drmProp);
> +	igt_assert(drmProp->count_enums);
> +
> +	return drmProp;
> +}
> +
> +gamma_lut_t *pipe_create_linear_lut(segment_data_t *info)

Identity transformation?

> +{
> +	uint32_t segment, entry, index = 0;
> +	double val;
> +	int i = 0;
> +	gamma_lut_t *gamma = alloc_lut(info->entries_count);
> +
> +	igt_assert(gamma);
> +
> +	gamma->size = info->entries_count;
> +	for (segment = 0; segment < info->segment_count; segment++) {
> +		uint32_t entry_count = info->segment_data[segment].count;
> +		uint32_t start = (segment == 0) ? 0 : (1 << (segment - 1));
> +		uint32_t end = 1 << segment;
> +
> +		for (entry = 0; entry < entry_count; entry++) {
> +			val = (index == 0) ? /* First entry is Zero. */
> +				0 : start + entry *
> +				((end - start) * 1.0 / entry_count);
> +
> +			set_rgb(&gamma->coeffs[i++], val);
> +			index++;
> +		}
> +	}
> +
> +	return gamma;
> +}
> +
>  drmModePropertyPtr get_plane_gamma_degamma_mode(igt_plane_t *plane,
>  				enum igt_atomic_plane_properties prop)
>  {
> @@ -331,6 +412,7 @@ segment_data_t *get_segment_data(data_t *data,
>  	info->segment_data = malloc(sizeof(struct drm_color_lut_range) * info->segment_count);
>  	igt_assert(info->segment_data);
>  
> +	info->entries_count = 0;

What's this?

>  	for (i = 0; i < info->segment_count; i++) {
>  		info->entries_count += lut_range[i].count;
>  		info->segment_data[i] = lut_range[i];
> @@ -341,6 +423,51 @@ segment_data_t *get_segment_data(data_t *data,
>  	return info;
>  }
>  
> +void set_advance_gamma(data_t *data, igt_pipe_t *pipe, enum gamma_type type)
> +{
> +	igt_display_t *display = &data->display;
> +	gamma_lut_t *gamma_log;
> +	drmModePropertyPtr gamma_mode = NULL;
> +	segment_data_t *segment_info = NULL;
> +	struct drm_color_lut *lut = NULL;
> +	int lut_size = 0;
> +
> +	drmSetClientCap(data->drm_fd, DRM_CLIENT_CAP_ADVANCE_GAMMA_MODES, 1);

Is this how we are going to do cross-software DRM-master hand-over or
switching compatibility in general?

Add a new client cap for every new KMS property, and if the KMS client
does not set the property, the kernel will magically reset it to ensure
the client's expectations are met? Is that how it works?

Or why does this exist?

> +	gamma_mode = get_pipe_gamma_degamma_mode(pipe, IGT_CRTC_GAMMA_MODE);
> +
> +	for (int i = 0; i < gamma_mode->count_enums; i++) {
> +		if (!strcmp(gamma_mode->enums[i].name, "logarithmic gamma")) {
> +			segment_info = get_segment_data(data,
> +							gamma_mode->enums[i].value,
> +							gamma_mode->enums[i].name);
> +			lut_size = sizeof(struct drm_color_lut) *
> +					  segment_info->entries_count;
> +			if (type == LINEAR_GAMMA) {
> +				gamma_log = pipe_create_linear_lut(segment_info);
> +				lut = coeffs_to_logarithmic_lut(data,
> +								gamma_log,
> +								data->color_depth,
> +								0);
> +			} else if (type == MAX_GAMMA) {
> +				gamma_log = generate_table_max(segment_info->entries_count);
> +				gamma_log->size = segment_info->entries_count;
> +				lut = coeffs_to_lut(data, gamma_log,
> +						    data->color_depth, 0);
> +			}
> +			set_pipe_gamma(pipe, gamma_mode->enums[i].value,
> +				       lut, lut_size);
> +			igt_display_commit2(display, display->is_atomic
> +					    ? COMMIT_ATOMIC : COMMIT_LEGACY);
> +			break;
> +		}
> +	}
> +	drmSetClientCap(data->drm_fd, DRM_CLIENT_CAP_ADVANCE_GAMMA_MODES, 0);

I've never seen this done before. I did not know client caps could be
reset.

> +	free(gamma_log);
> +	free(lut);
> +	clear_segment_data(segment_info);
> +	drmModeFreeProperty(gamma_mode);
> +}


Thanks,
pq

> +
>  void set_plane_gamma(igt_plane_t *plane,
>  		char *mode,
>  		struct drm_color_lut_ext *lut,
> diff --git a/tests/kms_color_helper.h b/tests/kms_color_helper.h
> index 5a35dcaac1..c863874f0c 100644
> --- a/tests/kms_color_helper.h
> +++ b/tests/kms_color_helper.h
> @@ -70,6 +70,11 @@ typedef struct {
>  	uint32_t entries_count;
>  } segment_data_t;
>  
> +enum gamma_type {
> +	LINEAR_GAMMA,
> +	MAX_GAMMA
> +};
> +
>  #define MIN(a, b) ((a) < (b) ? (a) : (b))
>  
>  void paint_gradient_rectangles(data_t *data,
> @@ -89,6 +94,10 @@ struct drm_color_lut *coeffs_to_lut(data_t *data,
>  				    const gamma_lut_t *gamma,
>  				    uint32_t color_depth,
>  				    int off);
> +struct drm_color_lut *coeffs_to_logarithmic_lut(data_t *data,
> +						const gamma_lut_t *gamma,
> +						uint32_t color_depth,
> +						int off);
>  void set_degamma(data_t *data,
>  		 igt_pipe_t *pipe,
>  		 const gamma_lut_t *gamma);
> @@ -98,12 +107,19 @@ void set_gamma(data_t *data,
>  void set_ctm(igt_pipe_t *pipe, const double *coefficients);
>  void disable_prop(igt_pipe_t *pipe, enum igt_atomic_crtc_properties prop);
>  
> +drmModePropertyPtr get_pipe_gamma_degamma_mode(igt_pipe_t *pipe,
> +					       enum igt_atomic_crtc_properties
> +					       prop);
>  drmModePropertyPtr get_plane_gamma_degamma_mode(igt_plane_t *plane,
>  	enum igt_atomic_plane_properties prop);
>  void clear_segment_data(segment_data_t *info);
> +gamma_lut_t *pipe_create_linear_lut(segment_data_t *info);
>  struct drm_color_lut_ext *create_linear_lut(segment_data_t *info);
>  struct drm_color_lut_ext *create_max_lut(segment_data_t *info);
>  segment_data_t *get_segment_data(data_t *data, uint64_t blob_id, char *mode);
> +void set_pipe_gamma(igt_pipe_t *pipe, uint64_t value,
> +		    struct drm_color_lut *lut, uint32_t size);
> +void set_advance_gamma(data_t *data, igt_pipe_t *pipe, enum gamma_type type);
>  void set_plane_gamma(igt_plane_t *plane,
>  	char *mode, struct drm_color_lut_ext *lut, uint32_t size);
>  void set_plane_degamma(igt_plane_t *plane,


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