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 at 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

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