[PATCH libdrm v3 0/9] util, modetest: Add support for low-color frame buffer formats

[PATCH libdrm v3 0/9] util, modetest: Add support for low-color frame buffer formats

[Geert Uytterhoeven]

	Hi all,

A long outstanding issue with the DRM subsystem has been the lack of
support for low-color displays, as used typically on older desktop
systems, and on small embedded displays.

This patch series adds support for color-indexed frame buffer formats
with 2, 4, and 16 colors.  It has been tested on ARAnyM using a
work-in-progress Atari DRM driver.

Changes compared to v2[1]:
  - Add Acked-by,
  - Add Wikipedia link,
  - Dropped "[RFC] drm_fourcc: Add DRM_FORMAT_C[124]", as these were
    added in commit 329eebcf32793361 ("drm_fourcc: sync drm_fourcc with
    latest drm-next kernel") in libdrm-2.4.115.

Changes compared to v1[2]:
  - SMPTE color LUT accuracy,
  - Factor out smpte color LUT,
  - Restructure patches,
  - Improve descriptions.
  - Store number of colors for indexed formats,
  - Add SMPTE pattern support for the C1 and C2 formats.

I have also opened a merge request at [3].

Thanks for your comments!

[1] https://lore.kernel.org/r/cover.1657302034.git.geert@linux-m68k.org/
[2] https://lore.kernel.org/r/cover.1646683737.git.geert@linux-m68k.org/
[3] https://gitlab.freedesktop.org/mesa/drm/-/merge_requests/314

Geert Uytterhoeven (9):
  util: Improve SMPTE color LUT accuracy
  util: Factor out and optimize C8 SMPTE color LUT
  util: Add support for DRM_FORMAT_C[124]
  util: Store number of colors for indexed formats
  util: Add SMPTE pattern support for C4 format
  util: Add SMPTE pattern support for C1 format
  util: Add SMPTE pattern support for C2 format
  modetest: Add support for DRM_FORMAT_C[124]
  modetest: Add SMPTE pattern support for C4 format

 tests/modetest/buffers.c  |  15 ++
 tests/modetest/modetest.c |   9 +-
 tests/util/format.c       |   5 +-
 tests/util/format.h       |   1 +
 tests/util/pattern.c      | 416 ++++++++++++++++++++++++++++++++++----
 tests/util/pattern.h      |   2 +-
 6 files changed, 405 insertions(+), 43 deletions(-)

-- 
2.34.1

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds

[PATCH libdrm v3 1/9] util: Improve SMPTE color LUT accuracy

[Geert Uytterhoeven]

Fill in the LSB when converting color components from 8-bit to 16-bit.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
---
v3:
  - Add Acked-by,

v2:
  - New.
---
 tests/util/pattern.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tests/util/pattern.c b/tests/util/pattern.c
index 158c0b160a2ee870..e85efdc893891bf7 100644
--- a/tests/util/pattern.c
+++ b/tests/util/pattern.c
@@ -646,9 +646,9 @@ void util_smpte_c8_gamma(unsigned size, struct drm_color_lut *lut)
 	memset(lut, 0, size * sizeof(struct drm_color_lut));
 
 #define FILL_COLOR(idx, r, g, b) \
-	lut[idx].red = (r) << 8; \
-	lut[idx].green = (g) << 8; \
-	lut[idx].blue = (b) << 8
+	lut[idx].red = (r) * 0x101; \
+	lut[idx].green = (g) * 0x101; \
+	lut[idx].blue = (b) * 0x101
 
 	FILL_COLOR( 0, 192, 192, 192);	/* grey */
 	FILL_COLOR( 1, 192, 192, 0  );	/* yellow */
-- 
2.34.1

[PATCH libdrm v3 2/9] util: Factor out and optimize C8 SMPTE color LUT

[Geert Uytterhoeven]

The color LUT for the SMPTE pattern in indexed mode contains 22 entries,
although only 13 are non-unique.

Reduce the size of the color LUT by dropping duplicate entries, so it
can be reused for formats supporting e.g. 16 colors.  Rename
util_smpte_c8_gamma() to util_smpte_index_gamma() accordingly.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
---
v3:
  - Add Acked-by,

v2:
  - Factor out smpte color LUT.
---
 tests/modetest/modetest.c |   2 +-
 tests/util/pattern.c      | 107 ++++++++++++++++++++++++++------------
 tests/util/pattern.h      |   2 +-
 3 files changed, 76 insertions(+), 35 deletions(-)

diff --git a/tests/modetest/modetest.c b/tests/modetest/modetest.c
index 42e2d1f477c3736b..ce91d404d747beb9 100644
--- a/tests/modetest/modetest.c
+++ b/tests/modetest/modetest.c
@@ -1122,7 +1122,7 @@ static void set_gamma(struct device *dev, unsigned crtc_id, unsigned fourcc)
 
 	if (fourcc == DRM_FORMAT_C8) {
 		/* TODO: Add C8 support for more patterns */
-		util_smpte_c8_gamma(256, gamma_lut);
+		util_smpte_index_gamma(256, gamma_lut);
 		drmModeCreatePropertyBlob(dev->fd, gamma_lut, sizeof(gamma_lut), &blob_id);
 	} else {
 		for (i = 0; i < 256; i++) {
diff --git a/tests/util/pattern.c b/tests/util/pattern.c
index e85efdc893891bf7..2132515681162d0f 100644
--- a/tests/util/pattern.c
+++ b/tests/util/pattern.c
@@ -605,6 +605,69 @@ static void fill_smpte_rgb16fp(const struct util_rgb_info *rgb, void *mem,
 	}
 }
 
+enum smpte_colors {
+	SMPTE_COLOR_GREY,
+	SMPTE_COLOR_YELLOW,
+	SMPTE_COLOR_CYAN,
+	SMPTE_COLOR_GREEN,
+	SMPTE_COLOR_MAGENTA,
+	SMPTE_COLOR_RED,
+	SMPTE_COLOR_BLUE,
+	SMPTE_COLOR_BLACK,
+	SMPTE_COLOR_IN_PHASE,
+	SMPTE_COLOR_SUPER_WHITE,
+	SMPTE_COLOR_QUADRATURE,
+	SMPTE_COLOR_3PC5,
+	SMPTE_COLOR_11PC5,
+};
+
+static const struct drm_color_lut smpte_color_lut[] = {
+	[SMPTE_COLOR_GREY] =        { 192 * 0x101, 192 * 0x101, 192 * 0x101 },
+	[SMPTE_COLOR_YELLOW] =      { 192 * 0x101, 192 * 0x101, 0   * 0x101 },
+	[SMPTE_COLOR_CYAN] =        { 0   * 0x101, 192 * 0x101, 192 * 0x101 },
+	[SMPTE_COLOR_GREEN] =       { 0   * 0x101, 192 * 0x101, 0   * 0x101 },
+	[SMPTE_COLOR_MAGENTA] =     { 192 * 0x101, 0   * 0x101, 192 * 0x101 },
+	[SMPTE_COLOR_RED] =         { 192 * 0x101, 0   * 0x101, 0   * 0x101 },
+	[SMPTE_COLOR_BLUE] =        { 0   * 0x101, 0   * 0x101, 192 * 0x101 },
+	[SMPTE_COLOR_BLACK] =       { 19  * 0x101, 19  * 0x101, 19  * 0x101 },
+	[SMPTE_COLOR_IN_PHASE] =    { 0   * 0x101, 33  * 0x101, 76  * 0x101 },
+	[SMPTE_COLOR_SUPER_WHITE] = { 255 * 0x101, 255 * 0x101, 255 * 0x101 },
+	[SMPTE_COLOR_QUADRATURE] =  { 50  * 0x101, 0   * 0x101, 106 * 0x101 },
+	[SMPTE_COLOR_3PC5] =        { 9   * 0x101, 9   * 0x101, 9   * 0x101 },
+	[SMPTE_COLOR_11PC5] =       { 29  * 0x101, 29  * 0x101, 29  * 0x101 },
+};
+
+static unsigned int smpte_top[7] = {
+	SMPTE_COLOR_GREY,
+	SMPTE_COLOR_YELLOW,
+	SMPTE_COLOR_CYAN,
+	SMPTE_COLOR_GREEN,
+	SMPTE_COLOR_MAGENTA,
+	SMPTE_COLOR_RED,
+	SMPTE_COLOR_BLUE,
+};
+
+static unsigned int smpte_middle[7] = {
+	SMPTE_COLOR_BLUE,
+	SMPTE_COLOR_BLACK,
+	SMPTE_COLOR_MAGENTA,
+	SMPTE_COLOR_BLACK,
+	SMPTE_COLOR_CYAN,
+	SMPTE_COLOR_BLACK,
+	SMPTE_COLOR_GREY,
+};
+
+static unsigned int smpte_bottom[8] = {
+	SMPTE_COLOR_IN_PHASE,
+	SMPTE_COLOR_SUPER_WHITE,
+	SMPTE_COLOR_QUADRATURE,
+	SMPTE_COLOR_BLACK,
+	SMPTE_COLOR_3PC5,
+	SMPTE_COLOR_BLACK,
+	SMPTE_COLOR_11PC5,
+	SMPTE_COLOR_BLACK,
+};
+
 static void fill_smpte_c8(void *mem, unsigned int width, unsigned int height,
 			  unsigned int stride)
 {
@@ -613,34 +676,35 @@ static void fill_smpte_c8(void *mem, unsigned int width, unsigned int height,
 
 	for (y = 0; y < height * 6 / 9; ++y) {
 		for (x = 0; x < width; ++x)
-			((uint8_t *)mem)[x] = x * 7 / width;
+			((uint8_t *)mem)[x] = smpte_top[x * 7 / width];
 		mem += stride;
 	}
 
 	for (; y < height * 7 / 9; ++y) {
 		for (x = 0; x < width; ++x)
-			((uint8_t *)mem)[x] = 7 + (x * 7 / width);
+			((uint8_t *)mem)[x] = smpte_middle[x * 7 / width];
 		mem += stride;
 	}
 
 	for (; y < height; ++y) {
 		for (x = 0; x < width * 5 / 7; ++x)
 			((uint8_t *)mem)[x] =
-				14 + (x * 4 / (width * 5 / 7));
+				smpte_bottom[x * 4 / (width * 5 / 7)];
 		for (; x < width * 6 / 7; ++x)
 			((uint8_t *)mem)[x] =
-				14 + ((x - width * 5 / 7) * 3
-					      / (width / 7) + 4);
+				smpte_bottom[(x - width * 5 / 7) * 3
+					     / (width / 7) + 4];
 		for (; x < width; ++x)
-			((uint8_t *)mem)[x] = 14 + 7;
+			((uint8_t *)mem)[x] = smpte_bottom[7];
 		mem += stride;
 	}
 }
 
-void util_smpte_c8_gamma(unsigned size, struct drm_color_lut *lut)
+void util_smpte_index_gamma(unsigned size, struct drm_color_lut *lut)
 {
-	if (size < 7 + 7 + 8) {
-		printf("Error: gamma too small: %d < %d\n", size, 7 + 7 + 8);
+	if (size < ARRAY_SIZE(smpte_color_lut)) {
+		printf("Error: gamma too small: %u < %zu\n", size,
+		       ARRAY_SIZE(smpte_color_lut));
 		return;
 	}
 	memset(lut, 0, size * sizeof(struct drm_color_lut));
@@ -650,30 +714,7 @@ void util_smpte_c8_gamma(unsigned size, struct drm_color_lut *lut)
 	lut[idx].green = (g) * 0x101; \
 	lut[idx].blue = (b) * 0x101
 
-	FILL_COLOR( 0, 192, 192, 192);	/* grey */
-	FILL_COLOR( 1, 192, 192, 0  );	/* yellow */
-	FILL_COLOR( 2, 0,   192, 192);	/* cyan */
-	FILL_COLOR( 3, 0,   192, 0  );	/* green */
-	FILL_COLOR( 4, 192, 0,   192);	/* magenta */
-	FILL_COLOR( 5, 192, 0,   0  );	/* red */
-	FILL_COLOR( 6, 0,   0,   192);	/* blue */
-
-	FILL_COLOR( 7, 0,   0,   192);	/* blue */
-	FILL_COLOR( 8, 19,  19,  19 );	/* black */
-	FILL_COLOR( 9, 192, 0,   192);	/* magenta */
-	FILL_COLOR(10, 19,  19,  19 );	/* black */
-	FILL_COLOR(11, 0,   192, 192);	/* cyan */
-	FILL_COLOR(12, 19,  19,  19 );	/* black */
-	FILL_COLOR(13, 192, 192, 192);	/* grey */
-
-	FILL_COLOR(14, 0,   33,  76);	/* in-phase */
-	FILL_COLOR(15, 255, 255, 255);	/* super white */
-	FILL_COLOR(16, 50,  0,   106);	/* quadrature */
-	FILL_COLOR(17, 19,  19,  19);	/* black */
-	FILL_COLOR(18, 9,   9,   9);	/* 3.5% */
-	FILL_COLOR(19, 19,  19,  19);	/* 7.5% */
-	FILL_COLOR(20, 29,  29,  29);	/* 11.5% */
-	FILL_COLOR(21, 19,  19,  19);	/* black */
+	memcpy(lut, smpte_color_lut, sizeof(smpte_color_lut));
 
 #undef FILL_COLOR
 }
diff --git a/tests/util/pattern.h b/tests/util/pattern.h
index ea38cafdcf27d811..d178bca69b227751 100644
--- a/tests/util/pattern.h
+++ b/tests/util/pattern.h
@@ -39,7 +39,7 @@ void util_fill_pattern(uint32_t format, enum util_fill_pattern pattern,
 		       void *planes[3], unsigned int width,
 		       unsigned int height, unsigned int stride);
 
-void util_smpte_c8_gamma(unsigned size, struct drm_color_lut *lut);
+void util_smpte_index_gamma(unsigned size, struct drm_color_lut *lut);
 
 enum util_fill_pattern util_pattern_enum(const char *name);
 
-- 
2.34.1

[PATCH libdrm v3 3/9] util: Add support for DRM_FORMAT_C[124]

[Geert Uytterhoeven]

Add support for creating buffers using the new color-indexed frame
buffer formats with two, four, and sixteen colors.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
---
v3:
  - Add Acked-by,

v2:
  - Split off changes to tests/util/format.c.
---
 tests/util/format.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tests/util/format.c b/tests/util/format.c
index 1ca1b82ce947b2f4..4b984af9bce8ac6f 100644
--- a/tests/util/format.c
+++ b/tests/util/format.c
@@ -40,6 +40,9 @@
 
 static const struct util_format_info format_info[] = {
 	/* Indexed */
+	{ DRM_FORMAT_C1, "C1" },
+	{ DRM_FORMAT_C2, "C2" },
+	{ DRM_FORMAT_C4, "C4" },
 	{ DRM_FORMAT_C8, "C8" },
 	/* YUV packed */
 	{ DRM_FORMAT_UYVY, "UYVY", MAKE_YUV_INFO(YUV_YCbCr | YUV_CY, 2, 2, 2) },
-- 
2.34.1

[PATCH libdrm v3 4/9] util: Store number of colors for indexed formats

[Geert Uytterhoeven]

Store the number of available colors for color-indexed frame
buffer formats in the format_info[] array.  This avoids the need of test
code for having to use switch statements all the time to obtain the
number of colors, or to check if a mode is color-indexed or not.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
---
v3:
  - Add Acked-by,

v2:
  - New.
---
 tests/util/format.c | 8 ++++----
 tests/util/format.h | 1 +
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/tests/util/format.c b/tests/util/format.c
index 4b984af9bce8ac6f..a5464de6fc1ac70f 100644
--- a/tests/util/format.c
+++ b/tests/util/format.c
@@ -40,10 +40,10 @@
 
 static const struct util_format_info format_info[] = {
 	/* Indexed */
-	{ DRM_FORMAT_C1, "C1" },
-	{ DRM_FORMAT_C2, "C2" },
-	{ DRM_FORMAT_C4, "C4" },
-	{ DRM_FORMAT_C8, "C8" },
+	{ DRM_FORMAT_C1, "C1", .ncolors = 2 },
+	{ DRM_FORMAT_C2, "C2", .ncolors = 4 },
+	{ DRM_FORMAT_C4, "C4", .ncolors = 16 },
+	{ DRM_FORMAT_C8, "C8", .ncolors = 256 },
 	/* YUV packed */
 	{ DRM_FORMAT_UYVY, "UYVY", MAKE_YUV_INFO(YUV_YCbCr | YUV_CY, 2, 2, 2) },
 	{ DRM_FORMAT_VYUY, "VYUY", MAKE_YUV_INFO(YUV_YCrCb | YUV_CY, 2, 2, 2) },
diff --git a/tests/util/format.h b/tests/util/format.h
index 2ce1c021fd78d51d..b847c9f2933b3cde 100644
--- a/tests/util/format.h
+++ b/tests/util/format.h
@@ -55,6 +55,7 @@ struct util_yuv_info {
 struct util_format_info {
 	uint32_t format;
 	const char *name;
+	unsigned int ncolors;
 	const struct util_rgb_info rgb;
 	const struct util_yuv_info yuv;
 };
-- 
2.34.1

[PATCH libdrm v3 5/9] util: Add SMPTE pattern support for C4 format

[Geert Uytterhoeven]

Add support for drawing the SMPTE pattern in a buffer using the C4
indexed format.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
---
v3:
  - Add Acked-by,

v2:
  - Use new smpte_top[],
  - Split off changes to tests/util/pattern.c.
---
 tests/util/pattern.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/tests/util/pattern.c b/tests/util/pattern.c
index 2132515681162d0f..c6e52d6666cda225 100644
--- a/tests/util/pattern.c
+++ b/tests/util/pattern.c
@@ -668,6 +668,46 @@ static unsigned int smpte_bottom[8] = {
 	SMPTE_COLOR_BLACK,
 };
 
+static void write_pixel_4(uint8_t *mem, unsigned int x, unsigned int pixel)
+{
+	if (x & 1)
+		mem[x / 2] = (mem[x / 2] & 0xf0) | (pixel & 0x0f);
+	else
+		mem[x / 2] = (mem[x / 2] & 0x0f) | (pixel << 4);
+}
+
+static void fill_smpte_c4(void *mem, unsigned int width, unsigned int height,
+			  unsigned int stride)
+{
+	unsigned int x;
+	unsigned int y;
+
+	for (y = 0; y < height * 6 / 9; ++y) {
+		for (x = 0; x < width; ++x)
+			write_pixel_4(mem, x, smpte_top[x * 7 / width]);
+		mem += stride;
+	}
+
+	for (; y < height * 7 / 9; ++y) {
+		for (x = 0; x < width; ++x)
+			write_pixel_4(mem, x, smpte_middle[x * 7 / width]);
+		mem += stride;
+	}
+
+	for (; y < height; ++y) {
+		for (x = 0; x < width * 5 / 7; ++x)
+			write_pixel_4(mem, x,
+				      smpte_bottom[x * 4 / (width * 5 / 7)]);
+		for (; x < width * 6 / 7; ++x)
+			write_pixel_4(mem, x,
+				      smpte_bottom[(x - width * 5 / 7) * 3 /
+						   (width / 7) + 4]);
+		for (; x < width; ++x)
+			write_pixel_4(mem, x, smpte_bottom[7]);
+		mem += stride;
+	}
+}
+
 static void fill_smpte_c8(void *mem, unsigned int width, unsigned int height,
 			  unsigned int stride)
 {
@@ -726,6 +766,8 @@ static void fill_smpte(const struct util_format_info *info, void *planes[3],
 	unsigned char *u, *v;
 
 	switch (info->format) {
+	case DRM_FORMAT_C4:
+		return fill_smpte_c4(planes[0], width, height, stride);
 	case DRM_FORMAT_C8:
 		return fill_smpte_c8(planes[0], width, height, stride);
 	case DRM_FORMAT_UYVY:
-- 
2.34.1

[PATCH libdrm v3 6/9] util: Add SMPTE pattern support for C1 format

[Geert Uytterhoeven]

Add support for drawing the SMPTE pattern in a buffer using the C1
indexed format.

As only two colors are available, the pattern is drawn in black and
white, using Floyd-Steinberg dithering[1].

[1] https://en.wikipedia.org/wiki/Floyd%E2%80%93Steinberg_dithering

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
---
Dithering example at https://drive.google.com/file/d/1waJczErrIaEKRhBCCU1ynxRG8agpo0Xx/view

v3:
  - Add Acked-by,
  - Add Wikipedia link,

v2:
  New.
---
 tests/util/pattern.c | 171 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 167 insertions(+), 4 deletions(-)

diff --git a/tests/util/pattern.c b/tests/util/pattern.c
index c6e52d6666cda225..b85a1f4728b8be1c 100644
--- a/tests/util/pattern.c
+++ b/tests/util/pattern.c
@@ -668,6 +668,163 @@ static unsigned int smpte_bottom[8] = {
 	SMPTE_COLOR_BLACK,
 };
 
+/*
+ * Floyd-Steinberg dithering
+ */
+
+struct fsd {
+	unsigned int width;
+	unsigned int x;
+	unsigned int i;
+	int red;
+	int green;
+	int blue;
+	int error[];
+};
+
+static struct fsd *fsd_alloc(unsigned int width)
+{
+	unsigned int n = 3 * (width + 1);
+	struct fsd *fsd = malloc(sizeof(*fsd) + n * sizeof(fsd->error[0]));
+
+	fsd->width = width;
+	fsd->x = 0;
+	fsd->i = 0;
+	memset(fsd->error, 0, n * sizeof(fsd->error[0]));
+
+	return fsd;
+}
+
+static inline int clamp(int val, int min, int max)
+{
+	if (val < min)
+		return min;
+	if (val > max)
+		return max;
+	return val;
+}
+
+static void fsd_dither(struct fsd *fsd, struct drm_color_lut *color)
+{
+	unsigned int i = fsd->i;
+
+	fsd->red = (int)color->red + (fsd->error[3 * i] + 8) / 16;
+	fsd->green = (int)color->green + (fsd->error[3 * i + 1] + 8) / 16;
+	fsd->blue = (int)color->blue + (fsd->error[3 * i + 2] + 8) / 16;
+
+	color->red = clamp(fsd->red, 0, 65535);
+	color->green = clamp(fsd->green, 0, 65535);
+	color->blue = clamp(fsd->blue, 0, 65535);
+}
+
+static void fsd_update(struct fsd *fsd, const struct drm_color_lut *actual)
+{
+	int error_red = fsd->red - (int)actual->red;
+	int error_green = fsd->green - (int)actual->green;
+	int error_blue = fsd->blue - (int)actual->blue;
+	unsigned int width = fsd->width;
+	unsigned int i = fsd->i, j;
+	unsigned int n = width + 1;
+
+	/* Distribute errors over neighboring pixels */
+	if (fsd->x == width - 1) {
+		/* Last pixel on this scanline */
+		/* South East: initialize to zero */
+		fsd->error[3 * i] = 0;
+		fsd->error[3 * i + 1] = 0;
+		fsd->error[3 * i + 2] = 0;
+	} else {
+		/* East: accumulate error */
+		j = (i + 1) % n;
+		fsd->error[3 * j] += 7 * error_red;
+		fsd->error[3 * j + 1] += 7 * error_green;
+		fsd->error[3 * j + 2] += 7 * error_blue;
+
+		/* South East: initial error */
+		fsd->error[3 * i] = error_red;
+		fsd->error[3 * i + 1] = error_green;
+		fsd->error[3 * i + 2] = error_blue;
+	}
+	/* South West: accumulate error */
+	j = (i + width - 1) % n;
+	fsd->error[3 * j] += 3 * error_red;
+	fsd->error[3 * j + 1] += 3 * error_green;
+	fsd->error[3 * j + 2] += 3 * error_blue;
+
+	/* South: accumulate error */
+	j = (i + width) % n;
+	fsd->error[3 * j] += 5 * error_red;
+	fsd->error[3 * j + 1] += 5 * error_green;
+	fsd->error[3 * j + 2] += 5 * error_blue;
+
+	fsd->x = (fsd->x + 1) % width;
+	fsd->i = (fsd->i + 1) % n;
+}
+
+static void write_pixel_1(uint8_t *mem, unsigned int x, unsigned int pixel)
+{
+	unsigned int shift = 7 - (x & 7);
+	unsigned int mask = 1U << shift;
+
+	mem[x / 8] = (mem[x / 8] & ~mask) | ((pixel << shift) & mask);
+}
+
+static void write_color_1(struct fsd *fsd, uint8_t *mem, unsigned int x,
+			  unsigned int index)
+{
+	struct drm_color_lut color = smpte_color_lut[index];
+	unsigned int pixel;
+
+	fsd_dither(fsd, &color);
+
+	/* ITU BT.601: Y = 0.299 R + 0.587 G + 0.114 B */
+	if (3 * color.red + 6 * color.green + color.blue >= 10 * 32768) {
+		pixel = 1;
+		color.red = color.green = color.blue = 65535;
+	} else {
+		pixel = 0;
+		color.red = color.green = color.blue = 0;
+	}
+
+	fsd_update(fsd, &color);
+
+	write_pixel_1(mem, x, pixel);
+}
+
+static void fill_smpte_c1(void *mem, unsigned int width, unsigned int height,
+			  unsigned int stride)
+{
+	struct fsd *fsd = fsd_alloc(width);
+	unsigned int x;
+	unsigned int y;
+
+	for (y = 0; y < height * 6 / 9; ++y) {
+		for (x = 0; x < width; ++x)
+			write_color_1(fsd, mem, x, smpte_top[x * 7 / width]);
+		mem += stride;
+	}
+
+	for (; y < height * 7 / 9; ++y) {
+		for (x = 0; x < width; ++x)
+			write_color_1(fsd, mem, x, smpte_middle[x * 7 / width]);
+		mem += stride;
+	}
+
+	for (; y < height; ++y) {
+		for (x = 0; x < width * 5 / 7; ++x)
+			write_color_1(fsd, mem, x,
+				      smpte_bottom[x * 4 / (width * 5 / 7)]);
+		for (; x < width * 6 / 7; ++x)
+			write_color_1(fsd, mem, x,
+				      smpte_bottom[(x - width * 5 / 7) * 3 /
+						   (width / 7) + 4]);
+		for (; x < width; ++x)
+			write_color_1(fsd, mem, x, smpte_bottom[7]);
+		mem += stride;
+	}
+
+	free(fsd);
+}
 static void write_pixel_4(uint8_t *mem, unsigned int x, unsigned int pixel)
 {
 	if (x & 1)
@@ -742,9 +899,8 @@ static void fill_smpte_c8(void *mem, unsigned int width, unsigned int height,
 
 void util_smpte_index_gamma(unsigned size, struct drm_color_lut *lut)
 {
-	if (size < ARRAY_SIZE(smpte_color_lut)) {
-		printf("Error: gamma too small: %u < %zu\n", size,
-		       ARRAY_SIZE(smpte_color_lut));
+	if (size < 2) {
+		printf("Error: gamma too small: %u < 2\n", size);
 		return;
 	}
 	memset(lut, 0, size * sizeof(struct drm_color_lut));
@@ -754,7 +910,12 @@ void util_smpte_index_gamma(unsigned size, struct drm_color_lut *lut)
 	lut[idx].green = (g) * 0x101; \
 	lut[idx].blue = (b) * 0x101
 
-	memcpy(lut, smpte_color_lut, sizeof(smpte_color_lut));
+	if (size < ARRAY_SIZE(smpte_color_lut)) {
+		FILL_COLOR(0, 0,   0,   0  );	/* black */
+		FILL_COLOR(1, 255, 255, 255);	/* white */
+	} else {
+		memcpy(lut, smpte_color_lut, sizeof(smpte_color_lut));
+	}
 
 #undef FILL_COLOR
 }
@@ -766,6 +927,8 @@ static void fill_smpte(const struct util_format_info *info, void *planes[3],
 	unsigned char *u, *v;
 
 	switch (info->format) {
+	case DRM_FORMAT_C1:
+		return fill_smpte_c1(planes[0], width, height, stride);
 	case DRM_FORMAT_C4:
 		return fill_smpte_c4(planes[0], width, height, stride);
 	case DRM_FORMAT_C8:
-- 
2.34.1

[PATCH libdrm v3 7/9] util: Add SMPTE pattern support for C2 format

[Geert Uytterhoeven]

Add support for drawing the SMPTE pattern in a buffer using the C2
indexed format.

As only four colors are available, resolution is halved, and the pattern
is drawn in a PenTile RG-GB matrix, using Floyd-Steinberg dithering.
The magnitude of the green subpixels is reduced, as there are twice as
many green subpixels as red or blue subpixels.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
---
Dithering example at https://drive.google.com/file/d/1g5O8XeacrjrC8rgaVENvR65YeI6QvmtO/view

v3:
  - Add Acked-by,

v2:
  - New.
---
 tests/util/pattern.c | 97 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 96 insertions(+), 1 deletion(-)

diff --git a/tests/util/pattern.c b/tests/util/pattern.c
index b85a1f4728b8be1c..1c6176b41506fa7d 100644
--- a/tests/util/pattern.c
+++ b/tests/util/pattern.c
@@ -825,6 +825,93 @@ static void fill_smpte_c1(void *mem, unsigned int width, unsigned int height,
 
 	free(fsd);
 }
+
+static void write_pixel_2(uint8_t *mem, unsigned int x, unsigned int pixel)
+{
+	unsigned int shift = 6 - 2 * (x & 3);
+	unsigned int mask = 3U << shift;
+
+	mem[x / 4] = (mem[x / 4] & ~mask) | ((pixel << shift) & mask);
+}
+
+static void write_color_2(struct fsd *fsd, uint8_t *mem, unsigned int stride,
+			  unsigned int x, unsigned int index)
+{
+	struct drm_color_lut color = smpte_color_lut[index];
+	unsigned int r, g, b;
+
+	fsd_dither(fsd, &color);
+
+	if (color.red >= 32768) {
+		r = 1;
+		color.red = 65535;
+	} else {
+		r = 0;
+		color.red = 0;
+	}
+	if (color.green >= 32768) {
+		g = 2;
+		color.green = 65535;
+	} else {
+		g = 0;
+		color.green = 0;
+	}
+	if (color.blue >= 32768) {
+		b = 3;
+		color.blue = 65535;
+	} else {
+		b = 0;
+		color.blue = 0;
+	}
+
+	fsd_update(fsd, &color);
+
+	/* Use PenTile RG-GB */
+	write_pixel_2(mem, 2 * x, r);
+	write_pixel_2(mem, 2 * x + 1, g);
+	write_pixel_2(mem + stride, 2 * x, g);
+	write_pixel_2(mem + stride, 2 * x + 1, b);
+}
+
+static void fill_smpte_c2(void *mem, unsigned int width, unsigned int height,
+			  unsigned int stride)
+{
+	struct fsd *fsd = fsd_alloc(width);
+	unsigned int x;
+	unsigned int y;
+
+	/* Half resolution for PenTile RG-GB */
+	width /= 2;
+	height /= 2;
+
+	for (y = 0; y < height * 6 / 9; ++y) {
+		for (x = 0; x < width; ++x)
+			write_color_2(fsd, mem, stride, x, smpte_top[x * 7 / width]);
+		mem += 2 * stride;
+	}
+
+	for (; y < height * 7 / 9; ++y) {
+		for (x = 0; x < width; ++x)
+			write_color_2(fsd, mem, stride, x, smpte_middle[x * 7 / width]);
+		mem += 2 * stride;
+	}
+
+	for (; y < height; ++y) {
+		for (x = 0; x < width * 5 / 7; ++x)
+			write_color_2(fsd, mem, stride, x,
+				      smpte_bottom[x * 4 / (width * 5 / 7)]);
+		for (; x < width * 6 / 7; ++x)
+			write_color_2(fsd, mem, stride, x,
+				      smpte_bottom[(x - width * 5 / 7) * 3 /
+						   (width / 7) + 4]);
+		for (; x < width; ++x)
+			write_color_2(fsd, mem, stride, x, smpte_bottom[7]);
+		mem += 2 * stride;
+	}
+
+	free(fsd);
+}
+
 static void write_pixel_4(uint8_t *mem, unsigned int x, unsigned int pixel)
 {
 	if (x & 1)
@@ -910,9 +997,15 @@ void util_smpte_index_gamma(unsigned size, struct drm_color_lut *lut)
 	lut[idx].green = (g) * 0x101; \
 	lut[idx].blue = (b) * 0x101
 
-	if (size < ARRAY_SIZE(smpte_color_lut)) {
+	if (size < 4) {
 		FILL_COLOR(0, 0,   0,   0  );	/* black */
 		FILL_COLOR(1, 255, 255, 255);	/* white */
+	} else if (size < ARRAY_SIZE(smpte_color_lut)) {
+		/* PenTile RG-GB */
+		FILL_COLOR(0, 0,   0,   0  );	/* black */
+		FILL_COLOR(1, 255, 0,   0  );	/* red */
+		FILL_COLOR(2, 0,   207, 0  );	/* green */
+		FILL_COLOR(3, 0,   0,   255);	/* blue */
 	} else {
 		memcpy(lut, smpte_color_lut, sizeof(smpte_color_lut));
 	}
@@ -929,6 +1022,8 @@ static void fill_smpte(const struct util_format_info *info, void *planes[3],
 	switch (info->format) {
 	case DRM_FORMAT_C1:
 		return fill_smpte_c1(planes[0], width, height, stride);
+	case DRM_FORMAT_C2:
+		return fill_smpte_c2(planes[0], width, height, stride);
 	case DRM_FORMAT_C4:
 		return fill_smpte_c4(planes[0], width, height, stride);
 	case DRM_FORMAT_C8:
-- 
2.34.1

[PATCH libdrm v3 8/9] modetest: Add support for DRM_FORMAT_C[124]

[Geert Uytterhoeven]

Add support for creating buffers using the new color-indexed frame
buffer formats with two, four, and sixteen colors.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
---
v3:
  - Add Acked-by,

v2:
  - Split off changes to tests/modetest/buffers.c.
---
 tests/modetest/buffers.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/tests/modetest/buffers.c b/tests/modetest/buffers.c
index 0b55aeddfef9a854..8af6201aca3034a9 100644
--- a/tests/modetest/buffers.c
+++ b/tests/modetest/buffers.c
@@ -124,6 +124,18 @@ bo_create(int fd, unsigned int format,
 	int ret;
 
 	switch (format) {
+	case DRM_FORMAT_C1:
+		bpp = 1;
+		break;
+
+	case DRM_FORMAT_C2:
+		bpp = 2;
+		break;
+
+	case DRM_FORMAT_C4:
+		bpp = 4;
+		break;
+
 	case DRM_FORMAT_C8:
 	case DRM_FORMAT_NV12:
 	case DRM_FORMAT_NV21:
@@ -272,6 +284,9 @@ bo_create(int fd, unsigned int format,
 		planes[2] = virtual + offsets[2];
 		break;
 
+	case DRM_FORMAT_C1:
+	case DRM_FORMAT_C2:
+	case DRM_FORMAT_C4:
 	case DRM_FORMAT_C8:
 	case DRM_FORMAT_ARGB4444:
 	case DRM_FORMAT_XRGB4444:
-- 
2.34.1

[PATCH libdrm v3 9/9] modetest: Add SMPTE pattern support for C4 format

[Geert Uytterhoeven]

Add support for drawing the SMPTE pattern in buffers using a
color-indexed frame buffer formats with two, four, or sixteen colors.

Note that this still uses 256 as the CLUT size, as
DRM_IOCTL_MODE_SETGAMMA enforces that the size matches against the
(fixed) gamma size, while the CLUT size depends on the format.

Move clearing the color LUT entries from util_smpte_index_gamma() to its
caller, as only the caller knows how many entries there really are
(currently DRM always assumes 256 entries).

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
---
v3:
  - Add Acked-by,

v2:
  - Split off changes to tests/modetest/modetest.c,
  - Add C1 and C2 support.

The linuxdoc comments say userspace can query the gamma size:

 * drm_mode_gamma_set_ioctl - set the gamma table
 *
 * Set the gamma table of a CRTC to the one passed in by the user. Userspace can
 * inquire the required gamma table size through drm_mode_gamma_get_ioctl.

 * drm_mode_gamma_get_ioctl - get the gamma table
 *
 * Copy the current gamma table into the storage provided. This also provides
 * the gamma table size the driver expects, which can be used to size the
 * allocated storage.

but the code doesn't seem to support that in an easy way (like setting
red/green/blue to NULL on input, retrieving gamma_size on output), only
by providing big enough buffers for red/green/blue, and looping over
gamma_size until -EINVAL is no longer returned.
---
 tests/modetest/modetest.c | 9 ++++++---
 tests/util/pattern.c      | 1 -
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/tests/modetest/modetest.c b/tests/modetest/modetest.c
index ce91d404d747beb9..ce334868df7bf12a 100644
--- a/tests/modetest/modetest.c
+++ b/tests/modetest/modetest.c
@@ -1116,13 +1116,16 @@ static bool add_property_optional(struct device *dev, uint32_t obj_id,
 static void set_gamma(struct device *dev, unsigned crtc_id, unsigned fourcc)
 {
 	unsigned blob_id = 0;
+	const struct util_format_info *info;
 	/* TODO: support 1024-sized LUTs, when the use-case arises */
 	struct drm_color_lut gamma_lut[256];
 	int i, ret;
 
-	if (fourcc == DRM_FORMAT_C8) {
-		/* TODO: Add C8 support for more patterns */
-		util_smpte_index_gamma(256, gamma_lut);
+	info = util_format_info_find(fourcc);
+	if (info->ncolors) {
+		memset(gamma_lut, 0, sizeof(gamma_lut));
+		/* TODO: Add index support for more patterns */
+		util_smpte_index_gamma(info->ncolors, gamma_lut);
 		drmModeCreatePropertyBlob(dev->fd, gamma_lut, sizeof(gamma_lut), &blob_id);
 	} else {
 		for (i = 0; i < 256; i++) {
diff --git a/tests/util/pattern.c b/tests/util/pattern.c
index 1c6176b41506fa7d..a757d3de76fe4a2d 100644
--- a/tests/util/pattern.c
+++ b/tests/util/pattern.c
@@ -990,7 +990,6 @@ void util_smpte_index_gamma(unsigned size, struct drm_color_lut *lut)
 		printf("Error: gamma too small: %u < 2\n", size);
 		return;
 	}
-	memset(lut, 0, size * sizeof(struct drm_color_lut));
 
 #define FILL_COLOR(idx, r, g, b) \
 	lut[idx].red = (r) * 0x101; \
-- 
2.34.1