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

From: Pekka Paalanen ppaalanen@gmail.com Sent: Thursday, November 18, 2021 3:15 PM To: Modem, Bhanuprakash bhanuprakash.modem@intel.com Cc: igt-dev@lists.freedesktop.org; dri-devel@lists.freedesktop.org; Kumar, Mukunda Pramodh mukunda.pramodh.kumar@intel.com; Juha-Pekka Heikkila juhapekka.heikkila@gmail.com; Shankar, Uma uma.shankar@intel.com Subject: Re: [i-g-t 12/14] kms_color_helper: Add helper functions to support logarithmic gamma mode

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.

Yeah, the comment is misleading and variable names also bit confusing.

As uapi supports U0.16 precision the max supported value would be (1 << 16) - 1 and Intel h/w supports max value of (1 << 24) so we need to scale the values accordingly.

So, need to drop h/w specific hardcoded stuff and read from uapi & rename the variables as below:

max_uapi_value = (1 << 16) - 1; max_hw_value = /* Read from the uapi. */

...

• 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?

Very good point. Need to explore on this. I think the expectation is: Whoever sets this property should clear before hand-over or switching the compatibility.

...

• 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,