drm: mali-dp: enable gamma support

Add gamma via the DRM GAMMA_LUT/GAMMA_LUT_SIZE CRTC
properties. The expected LUT size is 4096 in order
to produce as accurate a set of segments as possible.

This version uses only the green channel's gamma curve
to set the hardware curve on DP550/650. For the sake of
simplicity, it uses the same table of coefficients for
all 3 curves on DP500.

Signed-off-by: Mihail Atanassov <mihail.atanassov@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>

drivers/gpu/drm/arm/malidp_crtc.c

@@ -93,6 +93,108 @@ static void malidp_crtc_disable(struct drm_crtc *crtc)
 	}
 }
 
+static const struct gamma_curve_segment {
+	u16 start;
+	u16 end;
+} segments[MALIDP_COEFFTAB_NUM_COEFFS] = {
+	/* sector 0 */
+	{    0,    0 }, {    1,    1 }, {    2,    2 }, {    3,    3 },
+	{    4,    4 }, {    5,    5 }, {    6,    6 }, {    7,    7 },
+	{    8,    8 }, {    9,    9 }, {   10,   10 }, {   11,   11 },
+	{   12,   12 }, {   13,   13 }, {   14,   14 }, {   15,   15 },
+	/* sector 1 */
+	{   16,   19 }, {   20,   23 }, {   24,   27 }, {   28,   31 },
+	/* sector 2 */
+	{   32,   39 }, {   40,   47 }, {   48,   55 }, {   56,   63 },
+	/* sector 3 */
+	{   64,   79 }, {   80,   95 }, {   96,  111 }, {  112,  127 },
+	/* sector 4 */
+	{  128,  159 }, {  160,  191 }, {  192,  223 }, {  224,  255 },
+	/* sector 5 */
+	{  256,  319 }, {  320,  383 }, {  384,  447 }, {  448,  511 },
+	/* sector 6 */
+	{  512,  639 }, {  640,  767 }, {  768,  895 }, {  896, 1023 },
+	{ 1024, 1151 }, { 1152, 1279 }, { 1280, 1407 }, { 1408, 1535 },
+	{ 1536, 1663 }, { 1664, 1791 }, { 1792, 1919 }, { 1920, 2047 },
+	{ 2048, 2175 }, { 2176, 2303 }, { 2304, 2431 }, { 2432, 2559 },
+	{ 2560, 2687 }, { 2688, 2815 }, { 2816, 2943 }, { 2944, 3071 },
+	{ 3072, 3199 }, { 3200, 3327 }, { 3328, 3455 }, { 3456, 3583 },
+	{ 3584, 3711 }, { 3712, 3839 }, { 3840, 3967 }, { 3968, 4095 },
+};
+
+#define DE_COEFTAB_DATA(a, b) ((((a) & 0xfff) << 16) | (((b) & 0xfff)))
+
+static void malidp_generate_gamma_table(struct drm_property_blob *lut_blob,
+					u32 coeffs[MALIDP_COEFFTAB_NUM_COEFFS])
+{
+	struct drm_color_lut *lut = (struct drm_color_lut *)lut_blob->data;
+	int i;
+
+	for (i = 0; i < MALIDP_COEFFTAB_NUM_COEFFS; ++i) {
+		u32 a, b, delta_in, out_start, out_end;
+
+		delta_in = segments[i].end - segments[i].start;
+		/* DP has 12-bit internal precision for its LUTs. */
+		out_start = drm_color_lut_extract(lut[segments[i].start].green,
+						  12);
+		out_end = drm_color_lut_extract(lut[segments[i].end].green, 12);
+		a = (delta_in == 0) ? 0 : ((out_end - out_start) * 256) / delta_in;
+		b = out_start;
+		coeffs[i] = DE_COEFTAB_DATA(a, b);
+	}
+}
+
+/*
+ * Check if there is a new gamma LUT and if it is of an acceptable size. Also,
+ * reject any LUTs that use distinct red, green, and blue curves.
+ */
+static int malidp_crtc_atomic_check_gamma(struct drm_crtc *crtc,
+					  struct drm_crtc_state *state)
+{
+	struct malidp_crtc_state *mc = to_malidp_crtc_state(state);
+	struct drm_color_lut *lut;
+	size_t lut_size;
+	int i;
+
+	if (!state->color_mgmt_changed || !state->gamma_lut)
+		return 0;
+
+	if (crtc->state->gamma_lut &&
+	    (crtc->state->gamma_lut->base.id == state->gamma_lut->base.id))
+		return 0;
+
+	if (state->gamma_lut->length % sizeof(struct drm_color_lut))
+		return -EINVAL;
+
+	lut_size = state->gamma_lut->length / sizeof(struct drm_color_lut);
+	if (lut_size != MALIDP_GAMMA_LUT_SIZE)
+		return -EINVAL;
+
+	lut = (struct drm_color_lut *)state->gamma_lut->data;
+	for (i = 0; i < lut_size; ++i)
+		if (!((lut[i].red == lut[i].green) &&
+		      (lut[i].red == lut[i].blue)))
+			return -EINVAL;
+
+	if (!state->mode_changed) {
+		int ret;
+
+		state->mode_changed = true;
+		/*
+		 * Kerneldoc for drm_atomic_helper_check_modeset mandates that
+		 * it be invoked when the driver sets ->mode_changed. Since
+		 * changing the gamma LUT doesn't depend on any external
+		 * resources, it is safe to call it only once.
+		 */
+		ret = drm_atomic_helper_check_modeset(crtc->dev, state->state);
+		if (ret)
+			return ret;
+	}
+
+	malidp_generate_gamma_table(state->gamma_lut, mc->gamma_coeffs);
+	return 0;
+}
+
 static int malidp_crtc_atomic_check(struct drm_crtc *crtc,
 				    struct drm_crtc_state *state)
 {
@@ -168,7 +270,7 @@ static int malidp_crtc_atomic_check(struct drm_crtc *crtc,
 		}
 	}
 
-	return 0;
+	return malidp_crtc_atomic_check_gamma(crtc, state);
 }
 
 static const struct drm_crtc_helper_funcs malidp_crtc_helper_funcs = {
@@ -180,16 +282,19 @@ static const struct drm_crtc_helper_funcs malidp_crtc_helper_funcs = {
 
 static struct drm_crtc_state *malidp_crtc_duplicate_state(struct drm_crtc *crtc)
 {
-	struct malidp_crtc_state *state;
+	struct malidp_crtc_state *state, *old_state;
 
 	if (WARN_ON(!crtc->state))
 		return NULL;
 
+	old_state = to_malidp_crtc_state(crtc->state);
 	state = kmalloc(sizeof(*state), GFP_KERNEL);
 	if (!state)
 		return NULL;
 
 	__drm_atomic_helper_crtc_duplicate_state(crtc, &state->base);
+	memcpy(state->gamma_coeffs, old_state->gamma_coeffs,
+	       sizeof(state->gamma_coeffs));
 
 	return &state->base;
 }
@@ -244,6 +349,7 @@ static void malidp_crtc_disable_vblank(struct drm_crtc *crtc)
 }
 
 static const struct drm_crtc_funcs malidp_crtc_funcs = {
+	.gamma_set = drm_atomic_helper_legacy_gamma_set,
 	.destroy = drm_crtc_cleanup,
 	.set_config = drm_atomic_helper_set_config,
 	.page_flip = drm_atomic_helper_page_flip,
@@ -281,11 +387,15 @@ int malidp_crtc_init(struct drm_device *drm)
 
 	ret = drm_crtc_init_with_planes(drm, &malidp->crtc, primary, NULL,
 					&malidp_crtc_funcs, NULL);
+	if (ret)
+		goto crtc_cleanup_planes;
 
-	if (!ret) {
+	drm_crtc_helper_add(&malidp->crtc, &malidp_crtc_helper_funcs);
-		drm_crtc_helper_add(&malidp->crtc, &malidp_crtc_helper_funcs);
+	drm_mode_crtc_set_gamma_size(&malidp->crtc, MALIDP_GAMMA_LUT_SIZE);
-		return 0;
+	/* No inverse-gamma and color adjustments yet. */
-	}
+	drm_crtc_enable_color_mgmt(&malidp->crtc, 0, false, MALIDP_GAMMA_LUT_SIZE);
+
+	return 0;
 
 crtc_cleanup_planes:
 	malidp_de_planes_destroy(drm);

drivers/gpu/drm/arm/malidp_drv.c

@@ -34,6 +34,51 @@
 
 #define MALIDP_CONF_VALID_TIMEOUT	250
 
+static void malidp_write_gamma_table(struct malidp_hw_device *hwdev,
+				     u32 data[MALIDP_COEFFTAB_NUM_COEFFS])
+{
+	int i;
+	/* Update all channels with a single gamma curve. */
+	const u32 gamma_write_mask = GENMASK(18, 16);
+	/*
+	 * Always write an entire table, so the address field in
+	 * DE_COEFFTAB_ADDR is 0 and we can use the gamma_write_mask bitmask
+	 * directly.
+	 */
+	malidp_hw_write(hwdev, gamma_write_mask,
+			hwdev->map.coeffs_base + MALIDP_COEF_TABLE_ADDR);
+	for (i = 0; i < MALIDP_COEFFTAB_NUM_COEFFS; ++i)
+		malidp_hw_write(hwdev, data[i],
+				hwdev->map.coeffs_base +
+				MALIDP_COEF_TABLE_DATA);
+}
+
+static void malidp_atomic_commit_update_gamma(struct drm_crtc *crtc,
+					      struct drm_crtc_state *old_state)
+{
+	struct malidp_drm *malidp = crtc_to_malidp_device(crtc);
+	struct malidp_hw_device *hwdev = malidp->dev;
+
+	if (!crtc->state->color_mgmt_changed)
+		return;
+
+	if (!crtc->state->gamma_lut) {
+		malidp_hw_clearbits(hwdev,
+				    MALIDP_DISP_FUNC_GAMMA,
+				    MALIDP_DE_DISPLAY_FUNC);
+	} else {
+		struct malidp_crtc_state *mc =
+			to_malidp_crtc_state(crtc->state);
+
+		if (!old_state->gamma_lut || (crtc->state->gamma_lut->base.id !=
+					      old_state->gamma_lut->base.id))
+			malidp_write_gamma_table(hwdev, mc->gamma_coeffs);
+
+		malidp_hw_setbits(hwdev, MALIDP_DISP_FUNC_GAMMA,
+				  MALIDP_DE_DISPLAY_FUNC);
+	}
+}
+
 /*
  * set the "config valid" bit and wait until the hardware acts on it
  */
@@ -92,11 +137,17 @@ static void malidp_atomic_commit_hw_done(struct drm_atomic_state *state)
 static void malidp_atomic_commit_tail(struct drm_atomic_state *state)
 {
 	struct drm_device *drm = state->dev;
+	struct drm_crtc *crtc;
+	struct drm_crtc_state *old_crtc_state;
+	int i;
 
 	pm_runtime_get_sync(drm->dev);
 
 	drm_atomic_helper_commit_modeset_disables(drm, state);
 
+	for_each_crtc_in_state(state, crtc, old_crtc_state, i)
+		malidp_atomic_commit_update_gamma(crtc, old_crtc_state);
+
 	drm_atomic_helper_commit_planes(drm, state, 0);
 
 	drm_atomic_helper_commit_modeset_enables(drm, state);

drivers/gpu/drm/arm/malidp_drv.h

@@ -50,6 +50,7 @@ struct malidp_plane_state {
 
 struct malidp_crtc_state {
 	struct drm_crtc_state base;
+	u32 gamma_coeffs[MALIDP_COEFFTAB_NUM_COEFFS];
 };
 
 #define to_malidp_crtc_state(x) container_of(x, struct malidp_crtc_state, base)

drivers/gpu/drm/arm/malidp_hw.c

@@ -415,6 +415,7 @@ static int malidp650_query_hw(struct malidp_hw_device *hwdev)
 const struct malidp_hw_device malidp_device[MALIDP_MAX_DEVICES] = {
 	[MALIDP_500] = {
 		.map = {
+			.coeffs_base = MALIDP500_COEFFS_BASE,
 			.se_base = MALIDP500_SE_BASE,
 			.dc_base = MALIDP500_DC_BASE,
 			.out_depth_base = MALIDP500_OUTPUT_DEPTH,
@@ -451,6 +452,7 @@ const struct malidp_hw_device malidp_device[MALIDP_MAX_DEVICES] = {
 	},
 	[MALIDP_550] = {
 		.map = {
+			.coeffs_base = MALIDP550_COEFFS_BASE,
 			.se_base = MALIDP550_SE_BASE,
 			.dc_base = MALIDP550_DC_BASE,
 			.out_depth_base = MALIDP550_DE_OUTPUT_DEPTH,
@@ -485,6 +487,7 @@ const struct malidp_hw_device malidp_device[MALIDP_MAX_DEVICES] = {
 	},
 	[MALIDP_650] = {
 		.map = {
+			.coeffs_base = MALIDP550_COEFFS_BASE,
 			.se_base = MALIDP550_SE_BASE,
 			.dc_base = MALIDP550_DC_BASE,
 			.out_depth_base = MALIDP550_DE_OUTPUT_DEPTH,

drivers/gpu/drm/arm/malidp_hw.h

@@ -67,6 +67,8 @@ struct malidp_layer {
 struct malidp_hw_regmap {
 	/* address offset of the DE register bank */
 	/* is always 0x0000 */
+	/* address offset of the DE coefficients registers */
+	const u16 coeffs_base;
 	/* address offset of the SE registers bank */
 	const u16 se_base;
 	/* address offset of the DC registers bank */
@@ -257,4 +259,8 @@ static inline bool malidp_hw_pitch_valid(struct malidp_hw_device *hwdev,
 #define MALIDP_BGND_COLOR_G		0x000
 #define MALIDP_BGND_COLOR_B		0x000
 
+#define MALIDP_COEFFTAB_NUM_COEFFS	64
+
+#define MALIDP_GAMMA_LUT_SIZE		4096
+
 #endif  /* __MALIDP_HW_H__ */

drivers/gpu/drm/arm/malidp_regs.h

@@ -63,6 +63,7 @@
 
 /* bit masks that are common between products */
 #define   MALIDP_CFG_VALID		(1 << 0)
+#define   MALIDP_DISP_FUNC_GAMMA	(1 << 0)
 #define   MALIDP_DISP_FUNC_ILACED	(1 << 8)
 
 /* register offsets for IRQ management */
@@ -99,6 +100,11 @@
 
 #define MALIDP_PRODUCT_ID(__core_id) ((u32)(__core_id) >> 16)
 
+/* register offsets relative to MALIDP5x0_COEFFS_BASE */
+#define MALIDP_COLOR_ADJ_COEF		0x00000
+#define MALIDP_COEF_TABLE_ADDR		0x00030
+#define MALIDP_COEF_TABLE_DATA		0x00034
+
 /* register offsets and bits specific to DP500 */
 #define MALIDP500_ADDR_SPACE_SIZE	0x01000
 #define MALIDP500_DC_BASE		0x00000
@@ -120,6 +126,18 @@
 #define MALIDP500_COLOR_ADJ_COEF	0x00078
 #define MALIDP500_COEF_TABLE_ADDR	0x000a8
 #define MALIDP500_COEF_TABLE_DATA	0x000ac
+
+/*
+ * The YUV2RGB coefficients on the DP500 are not in the video layer's register
+ * block. They belong in a separate block above the layer's registers, hence
+ * the negative offset.
+ */
+#define MALIDP500_LV_YUV2RGB		((s16)(-0xB8))
+/*
+ * To match DP550/650, the start of the coeffs registers is
+ * at COLORADJ_COEFF0 instead of at YUV_RGB_COEF1.
+ */
+#define MALIDP500_COEFFS_BASE		0x00078
 #define MALIDP500_DE_LV_BASE		0x00100
 #define MALIDP500_DE_LV_PTR_BASE	0x00124
 #define MALIDP500_DE_LG1_BASE		0x00200
@@ -145,9 +163,7 @@
 #define MALIDP550_DE_DISP_SIDEBAND	0x00040
 #define MALIDP550_DE_BGND_COLOR		0x00044
 #define MALIDP550_DE_OUTPUT_DEPTH	0x0004c
-#define MALIDP550_DE_COLOR_COEF		0x00050
+#define MALIDP550_COEFFS_BASE		0x00050
-#define MALIDP550_DE_COEF_TABLE_ADDR	0x00080
-#define MALIDP550_DE_COEF_TABLE_DATA	0x00084
 #define MALIDP550_DE_LV1_BASE		0x00100
 #define MALIDP550_DE_LV1_PTR_BASE	0x00124
 #define MALIDP550_DE_LV2_BASE		0x00200