drm/mediatek: set mt8173 dithering function

Some panels only accept bpc (bit per color) 6-bit.
But, the default bpc in mt8173 display data path is 8-bit.
If we didn't enable dithering function to convert bpc,
display cannot show the smooth grayscale image.

In mt8173, the dithering function in OD (OverDrive) and
GAMMA module, we have to config them with
connector->display_mode.bpc when CRTC initial.

1. Clear the default value at *_DITHER_5 and *_DITHER_7 register.
2. Calculate the LSB_ERR_SHIFT bits and ADD_LSHIFT bits two values.
i.e. Input bpc of OD is 10 bits, we assume the bpc of panel is 6-bit,
so, we need to set 4-bit to LSB_ERR_SHIFT and ADD_LSHIFT bits respectively.
3. Then, set the OD or GAMMA to dithering mode depends on path-1 or path-2.

Signed-off-by: Bibby Hsieh <bibby.hsieh@mediatek.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
index 8f62671..019b7ca 100644 (file)
--- a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
@@ -103,7 +103,8 @@ static void mtk_ovl_stop(struct mtk_ddp_comp *comp)
 }
 
 static void mtk_ovl_config(struct mtk_ddp_comp *comp, unsigned int w,
-                          unsigned int h, unsigned int vrefresh)
+                          unsigned int h, unsigned int vrefresh,
+                          unsigned int bpc)
 {
        if (w != 0 && h != 0)
                writel_relaxed(h << 16 | w, comp->regs + DISP_REG_OVL_ROI_SIZE);

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_rdma.c b/drivers/gpu/drm/mediatek/mtk_disp_rdma.c
index 5fb80cb..0df05f9 100644 (file)
--- a/drivers/gpu/drm/mediatek/mtk_disp_rdma.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_rdma.c
@@ -106,7 +106,8 @@ static void mtk_rdma_stop(struct mtk_ddp_comp *comp)
 }
 
 static void mtk_rdma_config(struct mtk_ddp_comp *comp, unsigned int width,
-                           unsigned int height, unsigned int vrefresh)
+                           unsigned int height, unsigned int vrefresh,
+                           unsigned int bpc)
 {
        unsigned int threshold;
        unsigned int reg;

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
index e3ac280..58725d3 100644 (file)
--- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
@@ -222,7 +222,9 @@ static void mtk_crtc_ddp_clk_disable(struct mtk_drm_crtc *mtk_crtc)
 static int mtk_crtc_ddp_hw_init(struct mtk_drm_crtc *mtk_crtc)
 {
        struct drm_crtc *crtc = &mtk_crtc->base;
-       unsigned int width, height, vrefresh;
+       struct drm_connector *connector;
+       struct drm_encoder *encoder;
+       unsigned int width, height, vrefresh, bpc = MTK_MAX_BPC;
        int ret;
        int i;
 
@@ -234,6 +236,19 @@ static int mtk_crtc_ddp_hw_init(struct mtk_drm_crtc *mtk_crtc)
        height = crtc->state->adjusted_mode.vdisplay;
        vrefresh = crtc->state->adjusted_mode.vrefresh;
 
+       drm_for_each_encoder(encoder, crtc->dev) {
+               if (encoder->crtc != crtc)
+                       continue;
+
+               drm_for_each_connector(connector, crtc->dev) {
+                       if (connector->encoder != encoder)
+                               continue;
+                       if (connector->display_info.bpc != 0 &&
+                           bpc > connector->display_info.bpc)
+                               bpc = connector->display_info.bpc;
+               }
+       }
+
        ret = pm_runtime_get_sync(crtc->dev->dev);
        if (ret < 0) {
                DRM_ERROR("Failed to enable power domain: %d\n", ret);
@@ -266,7 +281,7 @@ static int mtk_crtc_ddp_hw_init(struct mtk_drm_crtc *mtk_crtc)
        for (i = 0; i < mtk_crtc->ddp_comp_nr; i++) {
                struct mtk_ddp_comp *comp = mtk_crtc->ddp_comp[i];
 
-               mtk_ddp_comp_config(comp, width, height, vrefresh);
+               mtk_ddp_comp_config(comp, width, height, vrefresh, bpc);
                mtk_ddp_comp_start(comp);
        }
 
@@ -468,7 +483,7 @@ void mtk_crtc_ddp_irq(struct drm_crtc *crtc, struct mtk_ddp_comp *ovl)
        if (state->pending_config) {
                mtk_ddp_comp_config(ovl, state->pending_width,
                                    state->pending_height,
-                                   state->pending_vrefresh);
+                                   state->pending_vrefresh, 0);
 
                state->pending_config = false;
        }

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.h b/drivers/gpu/drm/mediatek/mtk_drm_crtc.h
index d332564..33f6ab6 100644 (file)
--- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.h
+++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.h
@@ -20,6 +20,8 @@
 
 #define OVL_LAYER_NR   4
 #define MTK_LUT_SIZE   512
+#define MTK_MAX_BPC    10
+#define MTK_MIN_BPC    3
 
 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 42cd587..df33b3c 100644 (file)
--- a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
@@ -31,6 +31,10 @@
 #define DISP_OD_INTSTA                         0x000c
 #define DISP_OD_CFG                            0x0020
 #define DISP_OD_SIZE                           0x0030
+#define DISP_DITHER_5                          0x0114
+#define DISP_DITHER_7                          0x011c
+#define DISP_DITHER_15                         0x013c
+#define DISP_DITHER_16                         0x0140
 
 #define DISP_REG_UFO_START                     0x0000
 
@@ -49,20 +53,59 @@
 
 #define LUT_10BIT_MASK                         0x03ff
 
-#define        OD_RELAY_MODE           BIT(0)
+#define COLOR_BYPASS_ALL                       BIT(7)
+#define COLOR_SEQ_SEL                          BIT(13)
 
-#define        UFO_BYPASS              BIT(2)
+#define OD_RELAYMODE                           BIT(0)
 
-#define        COLOR_BYPASS_ALL        BIT(7)
-#define        COLOR_SEQ_SEL           BIT(13)
+#define UFO_BYPASS                             BIT(2)
 
-#define AAL_EN                 BIT(0)
+#define AAL_EN                                 BIT(0)
 
-#define GAMMA_EN               BIT(0)
-#define GAMMA_LUT_EN           BIT(1)
+#define GAMMA_EN                               BIT(0)
+#define GAMMA_LUT_EN                           BIT(1)
+
+#define DISP_DITHERING                         BIT(2)
+#define DITHER_LSB_ERR_SHIFT_R(x)              (((x) & 0x7) << 28)
+#define DITHER_OVFLW_BIT_R(x)                  (((x) & 0x7) << 24)
+#define DITHER_ADD_LSHIFT_R(x)                 (((x) & 0x7) << 20)
+#define DITHER_ADD_RSHIFT_R(x)                 (((x) & 0x7) << 16)
+#define DITHER_NEW_BIT_MODE                    BIT(0)
+#define DITHER_LSB_ERR_SHIFT_B(x)              (((x) & 0x7) << 28)
+#define DITHER_OVFLW_BIT_B(x)                  (((x) & 0x7) << 24)
+#define DITHER_ADD_LSHIFT_B(x)                 (((x) & 0x7) << 20)
+#define DITHER_ADD_RSHIFT_B(x)                 (((x) & 0x7) << 16)
+#define DITHER_LSB_ERR_SHIFT_G(x)              (((x) & 0x7) << 12)
+#define DITHER_OVFLW_BIT_G(x)                  (((x) & 0x7) << 8)
+#define DITHER_ADD_LSHIFT_G(x)                 (((x) & 0x7) << 4)
+#define DITHER_ADD_RSHIFT_G(x)                 (((x) & 0x7) << 0)
+
+void mtk_dither_set(struct mtk_ddp_comp *comp, unsigned int bpc,
+                   unsigned int CFG)
+{
+       /* If bpc equal to 0, the dithering function didn't be enabled */
+       if (bpc == 0)
+               return;
+
+       if (bpc >= MTK_MIN_BPC) {
+               writel(0, comp->regs + DISP_DITHER_5);
+               writel(0, comp->regs + DISP_DITHER_7);
+               writel(DITHER_LSB_ERR_SHIFT_R(MTK_MAX_BPC - bpc) |
+                      DITHER_ADD_LSHIFT_R(MTK_MAX_BPC - bpc) |
+                      DITHER_NEW_BIT_MODE,
+                      comp->regs + DISP_DITHER_15);
+               writel(DITHER_LSB_ERR_SHIFT_B(MTK_MAX_BPC - bpc) |
+                      DITHER_ADD_LSHIFT_B(MTK_MAX_BPC - bpc) |
+                      DITHER_LSB_ERR_SHIFT_G(MTK_MAX_BPC - bpc) |
+                      DITHER_ADD_LSHIFT_G(MTK_MAX_BPC - bpc),
+                      comp->regs + DISP_DITHER_16);
+               writel(DISP_DITHERING, comp->regs + CFG);
+       }
+}
 
 static void mtk_color_config(struct mtk_ddp_comp *comp, unsigned int w,
-                            unsigned int h, unsigned int vrefresh)
+                            unsigned int h, unsigned int vrefresh,
+                            unsigned int bpc)
 {
        writel(w, comp->regs + DISP_COLOR_WIDTH);
        writel(h, comp->regs + DISP_COLOR_HEIGHT);
@@ -76,14 +119,16 @@ static void mtk_color_start(struct mtk_ddp_comp *comp)
 }
 
 static void mtk_od_config(struct mtk_ddp_comp *comp, unsigned int w,
-                         unsigned int h, unsigned int vrefresh)
+                         unsigned int h, unsigned int vrefresh,
+                         unsigned int bpc)
 {
        writel(w << 16 | h, comp->regs + DISP_OD_SIZE);
+       writel(OD_RELAYMODE, comp->regs + OD_RELAYMODE);
+       mtk_dither_set(comp, bpc, DISP_OD_CFG);
 }
 
 static void mtk_od_start(struct mtk_ddp_comp *comp)
 {
-       writel(OD_RELAY_MODE, comp->regs + DISP_OD_CFG);
        writel(1, comp->regs + DISP_OD_EN);
 }
 
@@ -93,7 +138,8 @@ static void mtk_ufoe_start(struct mtk_ddp_comp *comp)
 }
 
 static void mtk_aal_config(struct mtk_ddp_comp *comp, unsigned int w,
-                          unsigned int h, unsigned int vrefresh)
+                          unsigned int h, unsigned int vrefresh,
+                          unsigned int bpc)
 {
        writel(h << 16 | w, comp->regs + DISP_AAL_SIZE);
 }
@@ -109,9 +155,11 @@ static void mtk_aal_stop(struct mtk_ddp_comp *comp)
 }
 
 static void mtk_gamma_config(struct mtk_ddp_comp *comp, unsigned int w,
-                            unsigned int h, unsigned int vrefresh)
+                            unsigned int h, unsigned int vrefresh,
+                            unsigned int bpc)
 {
        writel(h << 16 | w, comp->regs + DISP_GAMMA_SIZE);
+       mtk_dither_set(comp, bpc, DISP_GAMMA_CFG);
 }
 
 static void mtk_gamma_start(struct mtk_ddp_comp *comp)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h
index f4b7e0a..22a33ee 100644 (file)
--- a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h
+++ b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h
@@ -65,7 +65,7 @@ struct mtk_ddp_comp;
 
 struct mtk_ddp_comp_funcs {
        void (*config)(struct mtk_ddp_comp *comp, unsigned int w,
-                      unsigned int h, unsigned int vrefresh);
+                      unsigned int h, unsigned int vrefresh, unsigned int bpc);
        void (*start)(struct mtk_ddp_comp *comp);
        void (*stop)(struct mtk_ddp_comp *comp);
        void (*enable_vblank)(struct mtk_ddp_comp *comp, struct drm_crtc *crtc);
@@ -89,10 +89,10 @@ struct mtk_ddp_comp {
 
 static inline void mtk_ddp_comp_config(struct mtk_ddp_comp *comp,
                                       unsigned int w, unsigned int h,
-                                      unsigned int vrefresh)
+                                      unsigned int vrefresh, unsigned int bpc)
 {
        if (comp->funcs && comp->funcs->config)
-               comp->funcs->config(comp, w, h, vrefresh);
+               comp->funcs->config(comp, w, h, vrefresh, bpc);
 }
 
 static inline void mtk_ddp_comp_start(struct mtk_ddp_comp *comp)
@@ -156,5 +156,7 @@ int mtk_ddp_comp_init(struct device *dev, struct device_node *comp_node,
                      const struct mtk_ddp_comp_funcs *funcs);
 int mtk_ddp_comp_register(struct drm_device *drm, struct mtk_ddp_comp *comp);
 void mtk_ddp_comp_unregister(struct drm_device *drm, struct mtk_ddp_comp *comp);
+void mtk_dither_set(struct mtk_ddp_comp *comp, unsigned int bpc,
+                   unsigned int CFG);
 
 #endif /* MTK_DRM_DDP_COMP_H */