[igt-dev] [PATCH i-g-t 1/3] tests/kms_color_helper: Read deep-color capability from EDID

[Bhanuprakash Modem <bhanuprakash.modem@intel.com>]

Add a helper function to read the panel's deep-color capability
from EDID.

https://glenwing.github.io/docs/VESA-EEDID-A2.pdf
(3.6.1 Video Input Definition: 1 Byte)

-----------------------------------------------------------------
| 7 | 6 5 4 3 2 1 0 | Video Signal Interface: Bit 7             |
|---|---------------|-------------------------------------------|
| 1 | x x x x x x x | Input is a Digital Video Signal Interface |
-----------------------------------------------------------------

-----------------------------------------------------
| 7 | 6 5 4 | 3 2 1 0 | Color Bit Depth: Bits 6 → 4 |
|---|-------|---------|-----------------------------|
| 1 | 0 0 0 | x x x x | Color Bit Depth is undefined|
| 1 | 0 0 1 | x x x x | 6 Bits per Primary Color    |
| 1 | 0 1 0 | x x x x | 8 Bits per Primary Color    |
| 1 | 0 1 1 | x x x x | 10 Bits per Primary Color   |
| 1 | 1 0 0 | x x x x | 12 Bits per Primary Color   |
| 1 | 1 0 1 | x x x x | 14 Bits per Primary Color   |
| 1 | 1 1 0 | x x x x | 16 Bits per Primary Color   |
| 1 | 1 1 1 | x x x x | Reserved (Do Not Use)       |
|---|-------|---------|-----------------------------|

For deep-color we need atleast 10-bits.

Cc: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Bhanuprakash Modem <bhanuprakash.modem@intel.com>
---
 lib/igt_edid.c           | 16 ++++++++++++++++
 lib/igt_edid.h           |  1 +
 tests/kms_color_helper.c | 30 ++++++++++++++++++++++++++++++
 tests/kms_color_helper.h |  3 +++
 4 files changed, 50 insertions(+)

diff --git a/lib/igt_edid.c b/lib/igt_edid.c
index df346c4c8c..6864896977 100644
--- a/lib/igt_edid.c
+++ b/lib/igt_edid.c
@@ -349,6 +349,22 @@ size_t edid_get_size(const struct edid *edid)
 	       edid->extensions_len * sizeof(struct edid_ext);
 }
 
+/**
+ * edid_get_bit_depth: return the Color Bit Depth if Input is a Digital Video
+ * Signal Interface, else return zero.
+ */
+uint8_t edid_get_bit_depth(const struct edid *edid)
+{
+	/*
+	 * Video Signal Interface: Bit 7 (1:Digital, 0:Analog)
+	 * Color Bit Depth: Bits 6 → 4
+	 */
+	if (!(edid->input & (1 << 7)))
+		return 0;
+
+	return ((edid->input & (7 << 4)) >> 4);
+}
+
 /**
  * cea_sad_init_pcm:
  * @channels: the number of supported channels (max. 8)
diff --git a/lib/igt_edid.h b/lib/igt_edid.h
index aac2f4a208..bb328b5a89 100644
--- a/lib/igt_edid.h
+++ b/lib/igt_edid.h
@@ -377,6 +377,7 @@ void edid_update_checksum(struct edid *edid);
 void base_edid_update_checksum(struct edid *edid);
 size_t edid_get_size(const struct edid *edid);
 void edid_get_mfg(const struct edid *edid, char out[static 3]);
+uint8_t edid_get_bit_depth(const struct edid *edid);
 void detailed_timing_set_mode(struct detailed_timing *dt, drmModeModeInfo *mode,
 			      int width_mm, int height_mm);
 void detailed_timing_set_monitor_range_mode(struct detailed_timing *dt,
diff --git a/tests/kms_color_helper.c b/tests/kms_color_helper.c
index d71e7bb2e6..1adb4644c5 100644
--- a/tests/kms_color_helper.c
+++ b/tests/kms_color_helper.c
@@ -24,6 +24,36 @@
 
 #include "kms_color_helper.h"
 
+bool
+is_panel_supports_deep_color(int fd, drmModeConnector *connector)
+{
+	uint64_t edid_blob_id;
+	uint8_t bit_depth;
+	drmModePropertyBlobPtr edid_blob = NULL;
+
+	igt_assert(kmstest_get_property(fd, connector->connector_id,
+					DRM_MODE_OBJECT_CONNECTOR, "EDID", NULL,
+					&edid_blob_id, NULL));
+	edid_blob = drmModeGetPropertyBlob(fd, edid_blob_id);
+	igt_require_f(edid_blob, "EDID blob is NULL\n");
+
+	bit_depth = edid_get_bit_depth((const struct edid *) edid_blob->data);
+	drmModeFreePropertyBlob(edid_blob);
+
+	if (bit_depth > 0 && bit_depth < 7)
+		igt_info("Max supported bit depth: %d\n", ((bit_depth << 1) + 4));
+	else
+		igt_info("Max supported bit depth: Undefined\n");
+
+	return (bit_depth >= 3);
+}
+
+bool is_max_bpc_supported(igt_output_t *output)
+{
+	return igt_output_has_prop(output, IGT_CONNECTOR_MAX_BPC) &&
+		igt_output_get_prop(output, IGT_CONNECTOR_MAX_BPC);
+}
+
 void paint_gradient_rectangles(data_t *data,
 			       drmModeModeInfo *mode,
 			       color_t *colors,
diff --git a/tests/kms_color_helper.h b/tests/kms_color_helper.h
index bb6f0054f3..992087ac9c 100644
--- a/tests/kms_color_helper.h
+++ b/tests/kms_color_helper.h
@@ -36,6 +36,7 @@
 #include "drm.h"
 #include "drmtest.h"
 #include "igt.h"
+#include "igt_edid.h"
 
 
 /* Internal */
@@ -64,6 +65,8 @@ typedef struct {
 	color_t coeffs[];
 } gamma_lut_t;
 
+bool is_panel_supports_deep_color(int fd, drmModeConnector *connector);
+bool is_max_bpc_supported(igt_output_t *output);
 void paint_gradient_rectangles(data_t *data,
 			       drmModeModeInfo *mode,
 			       color_t *colors,
-- 
2.32.0