On Thu, 2021-01-28 at 16:28 +0800, CK Hu wrote:

On Thu, 2021-01-28 at 16:18 +0800, Hsin-Yi Wang wrote:

quoted

On Thu, Jan 28, 2021 at 4:10 PM Yongqiang Niu
[off-list ref] wrote:

quoted

On Thu, 2021-01-28 at 16:07 +0800, CK Hu wrote:

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On Thu, 2021-01-28 at 15:59 +0800, Yongqiang Niu wrote:

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On Thu, 2021-01-28 at 15:42 +0800, CK Hu wrote:

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Hi, Hsin-Yi:

On Thu, 2021-01-28 at 15:28 +0800, Hsin-Yi Wang wrote:

quoted

From: Yongqiang Niu <redacted>

for 5 or 6 bpc panel, we need enable dither function
to improve the display quality

Signed-off-by: Yongqiang Niu <redacted>
Signed-off-by: Hsin-Yi Wang <redacted>
---
 drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c | 44 ++++++++++++++++++++-
 1 file changed, 43 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
index 8173f709272be..e85625704d611 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c

@@ -53,7 +53,9 @@
 #define DITHER_EN                              BIT(0)
 #define DISP_DITHER_CFG                                0x0020
 #define DITHER_RELAY_MODE                      BIT(0)
+#define DITHER_ENGINE_EN                       BIT(1)
 #define DISP_DITHER_SIZE                       0x0030
+#define DITHER_REG(idx)                                (0x100 + (idx) * 4)

 #define LUT_10BIT_MASK                         0x03ff

@@ -313,8 +315,48 @@ static void mtk_dither_config(struct device *dev, unsigned int w,
 {
        struct mtk_ddp_comp_dev *priv = dev_get_drvdata(dev);

+       bool enable = false;
+
+       /* default value for dither reg 5 to 14 */
+       const u32 dither_setting[] = {
+               0x00000000, /* 5 */
+               0x00003002, /* 6 */
+               0x00000000, /* 7 */
+               0x00000000, /* 8 */
+               0x00000000, /* 9 */
+               0x00000000, /* 10 */
+               0x00000000, /* 11 */
+               0x00000011, /* 12 */
+               0x00000000, /* 13 */
+               0x00000000, /* 14 */

Could you explain what is this?

this is dither 5 to dither 14 setting
this will be useless, we just need set dither 5 and dither 7 like
mtk_ddp_write(cmdq_pkt, 0, comp, DISP_DITHER_5);
mtk_ddp_write(cmdq_pkt, 0, comp, DISP_DITHER_7);
other value is same with hardware default value.

quoted

quoted

+       };
+
+       if (bpc == 5 || bpc == 6) {
+               enable = true;
+               mtk_ddp_write(cmdq_pkt,
+                             DITHER_LSB_ERR_SHIFT_R(MTK_MAX_BPC - bpc) |
+                             DITHER_ADD_LSHIFT_R(MTK_MAX_BPC - bpc) |
+                             DITHER_NEW_BIT_MODE,
+                             &priv->cmdq_reg, priv->regs, DITHER_REG(15));
+               mtk_ddp_write(cmdq_pkt,
+                             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),

This result in 0x50505050, but previous version is 0x50504040, so this
version is correct and previous version is incorrect?

the new version set r g b 3 channel same, seams more reasonable

So all the setting of DISP_DITHER_5, DISP_DITHER_7, DISP_DITHER_15,
DISP_DITHER_16 is identical to mtk_dither_set(), so call
mtk_dither_set() instead of duplication here.

dither enable set in mtk_dither_set is
mtk_ddp_write(cmdq_pkt, DISP_DITHERING, comp, CFG);

that is different 8183 and mt8192.
mt8173 dither enable in gamma is bit2
mt8183 and mt8192 dither engine enable is bit 1

We can still call mtk_dither_set() for bpc is 5 or 6 here, though it
will be set to bit2,
but later in mtk_ddp_write(cmdq_pkt, enable ? DITHER_ENGINE_EN :
DITHER_RELAY_MODE, &priv->cmdq_reg, priv->regs, DISP_DITHER_CFG); it
will be correct back to bit 1.

Is this reasonable?

Looks weird. Maybe pass some information into mtk_dither_set() to set
DISP_DITHERING correctly. 

I find one thing need to be fixed. CFG should be lower case.

we could modify this like this:

void mtk_dither_set(struct mtk_ddp_comp *comp, unsigned int bpc,
		    unsigned int cfg, u32 dither_enable, struct cmdq_pkt *cmdq_pkt)

		mtk_ddp_write(cmdq_pkt, dither_enable, comp, cfg);

Regards,
CK

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Regards,
CK

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Regards,
CK

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+                             &priv->cmdq_reg, priv->regs, DITHER_REG(16));
+       }
+
+
+       if (enable) {
+               u32 idx;
+
+               for (idx = 0; idx < ARRAY_SIZE(dither_setting); idx++)
+                       mtk_ddp_write(cmdq_pkt, dither_setting[idx], &priv->cmdq_reg, priv->regs,
+                                     DITHER_REG(idx + 5));
+       }
+
        mtk_ddp_write(cmdq_pkt, h << 16 | w, &priv->cmdq_reg, priv->regs, DISP_DITHER_SIZE);
-       mtk_ddp_write(cmdq_pkt, DITHER_RELAY_MODE, &priv->cmdq_reg, priv->regs, DISP_DITHER_CFG);
+        mtk_ddp_write(cmdq_pkt, enable ? DITHER_ENGINE_EN : DITHER_RELAY_MODE, &priv->cmdq_reg, priv->regs, DISP_DITHER_CFG);
 }

 static void mtk_dither_start(struct device *dev)

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