[PATCH v1, 1/1] drm/mediatek: add lut diff flag for new gamma hardware support

[Yongqiang Niu]

From: Yongqiang Niu <yongqiang.niu at mediatek.corp-partner.google.com>

mt8183 gamma module usage is different with before soc,
gamma odd(index start from 0) lut value set to hardware
register should be
the difference of current lut value with last lut value.

gamma function support both increase and decrease lut.
chrome os app set increase lut normally.

for increase lut example, chrome os user space set lut
like this(only r chanel for example):
2 4 6 8 10 12.
1) mt8183 gamma driver should set the gamma lut to hardware
register like this:
2 [2] 6 [8] 10 [2]
the value with [] is the difference value
2) gamma hardware will restore the lut when apply gamma
function to display

Signed-off-by: Yongqiang Niu <yongqiang.niu at mediatek.corp-partner.google.com>
---
 drivers/gpu/drm/mediatek/mtk_disp_aal.c   |  4 ++-
 drivers/gpu/drm/mediatek/mtk_disp_drv.h   |  2 +-
 drivers/gpu/drm/mediatek/mtk_disp_gamma.c | 34 +++++++++++++++++++----
 3 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_aal.c b/drivers/gpu/drm/mediatek/mtk_disp_aal.c
index f46d4ab73d6a..e6378b074a17 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_aal.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_aal.c
@@ -23,6 +23,7 @@
 
 struct mtk_disp_aal_data {
 	bool has_gamma;
+	bool lut_diff;
 };
 
 /**
@@ -66,7 +67,7 @@ void mtk_aal_gamma_set(struct device *dev, struct drm_crtc_state *state)
 	struct mtk_disp_aal *aal = dev_get_drvdata(dev);
 
 	if (aal->data && aal->data->has_gamma)
-		mtk_gamma_set_common(aal->regs, state);
+		mtk_gamma_set_common(aal->regs, state, aal->data->lut_diff);
 }
 
 void mtk_aal_start(struct device *dev)
@@ -148,6 +149,7 @@ static int mtk_disp_aal_remove(struct platform_device *pdev)
 
 static const struct mtk_disp_aal_data mt8173_aal_driver_data = {
 	.has_gamma = true,
+	.lut_diff = false,
 };
 
 static const struct of_device_id mtk_disp_aal_driver_dt_match[] = {
diff --git a/drivers/gpu/drm/mediatek/mtk_disp_drv.h b/drivers/gpu/drm/mediatek/mtk_disp_drv.h
index 86c3068894b1..3380651c6707 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_drv.h
+++ b/drivers/gpu/drm/mediatek/mtk_disp_drv.h
@@ -51,7 +51,7 @@ void mtk_gamma_config(struct device *dev, unsigned int w,
 		      unsigned int h, unsigned int vrefresh,
 		      unsigned int bpc, struct cmdq_pkt *cmdq_pkt);
 void mtk_gamma_set(struct device *dev, struct drm_crtc_state *state);
-void mtk_gamma_set_common(void __iomem *regs, struct drm_crtc_state *state);
+void mtk_gamma_set_common(void __iomem *regs, struct drm_crtc_state *state, bool lut_diff);
 void mtk_gamma_start(struct device *dev);
 void mtk_gamma_stop(struct device *dev);
 
diff --git a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
index 3a5815ab4079..fec2e9a5b60d 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
@@ -27,6 +27,7 @@
 
 struct mtk_disp_gamma_data {
 	bool has_dither;
+	bool lut_diff;
 };
 
 /*
@@ -53,12 +54,13 @@ void mtk_gamma_clk_disable(struct device *dev)
 	clk_disable_unprepare(gamma->clk);
 }
 
-void mtk_gamma_set_common(void __iomem *regs, struct drm_crtc_state *state)
+void mtk_gamma_set_common(void __iomem *regs, struct drm_crtc_state *state, bool lut_diff)
 {
 	unsigned int i, reg;
 	struct drm_color_lut *lut;
 	void __iomem *lut_base;
 	u32 word;
+	u32 diff[3] = {0};
 
 	if (state->gamma_lut) {
 		reg = readl(regs + DISP_GAMMA_CFG);
@@ -67,9 +69,20 @@ void mtk_gamma_set_common(void __iomem *regs, struct drm_crtc_state *state)
 		lut_base = regs + DISP_GAMMA_LUT;
 		lut = (struct drm_color_lut *)state->gamma_lut->data;
 		for (i = 0; i < MTK_LUT_SIZE; i++) {
-			word = (((lut[i].red >> 6) & LUT_10BIT_MASK) << 20) +
-				(((lut[i].green >> 6) & LUT_10BIT_MASK) << 10) +
-				((lut[i].blue >> 6) & LUT_10BIT_MASK);
+
+			if (!lut_diff || (i % 2 == 0)) {
+				word = (((lut[i].red >> 6) & LUT_10BIT_MASK) << 20) +
+					(((lut[i].green >> 6) & LUT_10BIT_MASK) << 10) +
+					((lut[i].blue >> 6) & LUT_10BIT_MASK);
+			} else {
+				diff[0] = abs((lut[i].red >> 6) - (lut[i - 1].red >> 6));
+				diff[1] = abs((lut[i].green >> 6) - (lut[i - 1].green >> 6));
+				diff[2] = abs((lut[i].blue >> 6) - (lut[i - 1].blue >> 6));
+
+				word = ((diff[0] & LUT_10BIT_MASK) << 20) +
+					((diff[1] & LUT_10BIT_MASK) << 10) +
+					(diff[2] & LUT_10BIT_MASK);
+			}
 			writel(word, (lut_base + i * 4));
 		}
 	}
@@ -78,8 +91,12 @@ void mtk_gamma_set_common(void __iomem *regs, struct drm_crtc_state *state)
 void mtk_gamma_set(struct device *dev, struct drm_crtc_state *state)
 {
 	struct mtk_disp_gamma *gamma = dev_get_drvdata(dev);
+	bool lut_diff = false;
+
+	if (gamma->data)
+		lut_diff = gamma->data->lut_diff;
 
-	mtk_gamma_set_common(gamma->regs, state);
+	mtk_gamma_set_common(gamma->regs, state, lut_diff);
 }
 
 void mtk_gamma_config(struct device *dev, unsigned int w,
@@ -176,10 +193,15 @@ static const struct mtk_disp_gamma_data mt8173_gamma_driver_data = {
 	.has_dither = true,
 };
 
+static const struct mtk_disp_gamma_data mt8183_gamma_driver_data = {
+	.lut_diff = true,
+};
+
 static const struct of_device_id mtk_disp_gamma_driver_dt_match[] = {
 	{ .compatible = "mediatek,mt8173-disp-gamma",
 	  .data = &mt8173_gamma_driver_data},
-	{ .compatible = "mediatek,mt8183-disp-gamma"},
+	{ .compatible = "mediatek,mt8183-disp-gamma",
+	  .data = &mt8183_gamma_driver_data},
 	{},
 };
 MODULE_DEVICE_TABLE(of, mtk_disp_gamma_driver_dt_match);
-- 
2.25.1