[PATCH 1/2] drm/mediatek: Add gamma correction

[Bibby Hsieh <bibby.hsieh@mediatek.com>]

Apply gamma function to correct brightness values.
It applies arbitrary mapping curve to compensate the
incorrect transfer function of the panel.

Signed-off-by: Bibby Hsieh <bibby.hsieh@mediatek.com>
---
 drivers/gpu/drm/mediatek/mtk_drm_crtc.c     |   12 ++++++
 drivers/gpu/drm/mediatek/mtk_drm_crtc.h     |    1 +
 drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c |   56 ++++++++++++++++++++++++++-
 drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h |    9 +++++
 4 files changed, 77 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
index 24aa3ba..1b38406 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
@@ -127,6 +127,16 @@ static void mtk_drm_crtc_reset(struct drm_crtc *crtc)
 	state->base.crtc = crtc;
 }
 
+static void mtk_crtc_gamma_set(struct drm_crtc *crtc, u16 *r,
+			       u16 *g, u16 *b, uint32_t start, uint32_t size)
+{
+	struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
+	unsigned int i;
+
+	for (i = 0; i < mtk_crtc->ddp_comp_nr; i++)
+		mtk_ddp_gamma_set(mtk_crtc->ddp_comp[i], r, g, b, start, size);
+}
+
 static struct drm_crtc_state *mtk_drm_crtc_duplicate_state(struct drm_crtc *crtc)
 {
 	struct mtk_crtc_state *state;
@@ -418,6 +428,7 @@ static const struct drm_crtc_funcs mtk_crtc_funcs = {
 	.reset			= mtk_drm_crtc_reset,
 	.atomic_duplicate_state	= mtk_drm_crtc_duplicate_state,
 	.atomic_destroy_state	= mtk_drm_crtc_destroy_state,
+	.gamma_set		= mtk_crtc_gamma_set,
 };
 
 static const struct drm_crtc_helper_funcs mtk_crtc_helper_funcs = {
@@ -569,6 +580,7 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
 	if (ret < 0)
 		goto unprepare;
 
+	drm_mode_crtc_set_gamma_size(&mtk_crtc->base, MTK_LUT_SIZE);
 	priv->crtc[pipe] = &mtk_crtc->base;
 	priv->num_pipes++;
 
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.h b/drivers/gpu/drm/mediatek/mtk_drm_crtc.h
index 81e5566..d332564 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.h
+++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.h
@@ -19,6 +19,7 @@
 #include "mtk_drm_plane.h"
 
 #define OVL_LAYER_NR	4
+#define MTK_LUT_SIZE	512
 
 int mtk_drm_crtc_enable_vblank(struct drm_device *drm, unsigned int pipe);
 void mtk_drm_crtc_disable_vblank(struct drm_device *drm, unsigned int pipe);
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
index 3970fcf..3fd5141 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
@@ -24,6 +24,7 @@
 #include "mtk_drm_drv.h"
 #include "mtk_drm_plane.h"
 #include "mtk_drm_ddp_comp.h"
+#include "mtk_drm_crtc.h"
 
 #define DISP_OD_EN				0x0000
 #define DISP_OD_INTEN				0x0008
@@ -38,6 +39,18 @@
 #define DISP_COLOR_WIDTH			0x0c50
 #define DISP_COLOR_HEIGHT			0x0c54
 
+#define DISP_AAL_EN				0x000
+#define DISP_AAL_SIZE				0x030
+
+#define DISP_GAMMA_CFG				0x020
+#define DISP_GAMMA_LUT				0x700
+
+#define LUT_10BIT_MASK				0x3ff
+
+#define AAL_EN			BIT(0)
+
+#define GAMMA_LUT_EN		BIT(1)
+
 #define	OD_RELAY_MODE		BIT(0)
 
 #define	UFO_BYPASS		BIT(2)
@@ -76,6 +89,40 @@ static void mtk_ufoe_start(struct mtk_ddp_comp *comp)
 	writel(UFO_BYPASS, comp->regs + DISP_REG_UFO_START);
 }
 
+static void mtk_aal_config(struct mtk_ddp_comp *comp, unsigned int w,
+			   unsigned int h, unsigned int vrefresh)
+{
+	writel(h << 16 | w, comp->regs + DISP_AAL_SIZE);
+}
+
+static void mtk_aal_start(struct mtk_ddp_comp *comp)
+{
+	writel(AAL_EN, comp->regs  + DISP_AAL_EN);
+}
+
+static void mtk_aal_stop(struct mtk_ddp_comp *comp)
+{
+	writel_relaxed(0x0, comp->regs  + DISP_AAL_EN);
+}
+
+static void mtk_gamma_set(struct mtk_ddp_comp *comp, u16 *r, u16 *g,
+			  u16 *b, uint32_t start, uint32_t size)
+{
+	int i;
+	unsigned int lut;
+	int end = (start + size > MTK_LUT_SIZE) ? MTK_LUT_SIZE : start + size;
+	void __iomem *lut_base;
+
+	writel(GAMMA_LUT_EN, comp->regs + DISP_GAMMA_CFG);
+	lut_base = comp->regs + DISP_GAMMA_LUT;
+	for (i = start; i < end; i++) {
+		lut = (((r[i] >> 6) & LUT_10BIT_MASK) << 20) +
+			(((g[i] >> 6) & LUT_10BIT_MASK) << 10) +
+			((b[i] >> 6) & LUT_10BIT_MASK);
+		writel(lut, (lut_base + i * 4));
+	}
+}
+
 static const struct mtk_ddp_comp_funcs ddp_color = {
 	.config = mtk_color_config,
 	.start = mtk_color_start,
@@ -90,6 +137,13 @@ static const struct mtk_ddp_comp_funcs ddp_ufoe = {
 	.start = mtk_ufoe_start,
 };
 
+static const struct mtk_ddp_comp_funcs ddp_aal = {
+	.gamma_set = mtk_gamma_set,
+	.config = mtk_aal_config,
+	.start = mtk_aal_start,
+	.stop = mtk_aal_stop,
+};
+
 static const char * const mtk_ddp_comp_stem[MTK_DDP_COMP_TYPE_MAX] = {
 	[MTK_DISP_OVL] = "ovl",
 	[MTK_DISP_RDMA] = "rdma",
@@ -112,7 +166,7 @@ struct mtk_ddp_comp_match {
 };
 
 static const struct mtk_ddp_comp_match mtk_ddp_matches[DDP_COMPONENT_ID_MAX] = {
-	[DDP_COMPONENT_AAL]	= { MTK_DISP_AAL,	0, NULL },
+	[DDP_COMPONENT_AAL]	= { MTK_DISP_AAL,	0, &ddp_aal },
 	[DDP_COMPONENT_COLOR0]	= { MTK_DISP_COLOR,	0, &ddp_color },
 	[DDP_COMPONENT_COLOR1]	= { MTK_DISP_COLOR,	1, &ddp_color },
 	[DDP_COMPONENT_DPI0]	= { MTK_DPI,		0, NULL },
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h
index 6b13ba9..0832179 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h
+++ b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h
@@ -73,6 +73,8 @@ struct mtk_ddp_comp_funcs {
 	void (*layer_off)(struct mtk_ddp_comp *comp, unsigned int idx);
 	void (*layer_config)(struct mtk_ddp_comp *comp, unsigned int idx,
 			     struct mtk_plane_state *state);
+	void (*gamma_set)(struct mtk_ddp_comp *comp, u16 *r, u16 *g, u16 *b,
+			  u32 start, u32 size);
 };
 
 struct mtk_ddp_comp {
@@ -139,6 +141,13 @@ static inline void mtk_ddp_comp_layer_config(struct mtk_ddp_comp *comp,
 		comp->funcs->layer_config(comp, idx, state);
 }
 
+static inline void mtk_ddp_gamma_set(struct mtk_ddp_comp *comp, u16 *r, u16 *g,
+				     u16 *b, uint32_t start, uint32_t size)
+{
+	if (comp->funcs && comp->funcs->gamma_set)
+		comp->funcs->gamma_set(comp, r, g, b, start, size);
+}
+
 int mtk_ddp_comp_get_id(struct device_node *node,
 			enum mtk_ddp_comp_type comp_type);
 int mtk_ddp_comp_init(struct device *dev, struct device_node *comp_node,
-- 
1.7.9.5