Move the write to DISP_GAMMA_CFG to enable the Gamma LUT to after
programming the actual table to avoid potential visual glitches during
table modification.

Signed-off-by: AngeloGioacchino Del Regno 
<angelogioacchino.delre...@collabora.com>
---
 drivers/gpu/drm/mediatek/mtk_disp_gamma.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c 
b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
index 89a1640c2e8f..97b34963ef73 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
@@ -71,12 +71,12 @@ unsigned int mtk_gamma_get_lut_size(struct device *dev)
 void mtk_gamma_set_common(struct device *dev, void __iomem *regs, struct 
drm_crtc_state *state)
 {
        struct mtk_disp_gamma *gamma = dev_get_drvdata(dev);
-       unsigned int i, reg;
+       unsigned int i;
        struct drm_color_lut *lut;
        void __iomem *lut_base;
        bool lut_diff;
        u16 lut_size;
-       u32 word;
+       u32 cfg_val, word;
 
        /* If there's no gamma lut there's nothing to do here. */
        if (!state->gamma_lut)
@@ -90,9 +90,7 @@ void mtk_gamma_set_common(struct device *dev, void __iomem 
*regs, struct drm_crt
                lut_size = LUT_SIZE_DEFAULT;
        }
 
-       reg = readl(regs + DISP_GAMMA_CFG);
-       reg = reg | GAMMA_LUT_EN;
-       writel(reg, regs + DISP_GAMMA_CFG);
+       cfg_val = readl(regs + DISP_GAMMA_CFG);
        lut_base = regs + DISP_GAMMA_LUT;
        lut = (struct drm_color_lut *)state->gamma_lut->data;
        for (i = 0; i < lut_size; i++) {
@@ -122,6 +120,11 @@ void mtk_gamma_set_common(struct device *dev, void __iomem 
*regs, struct drm_crt
                }
                writel(word, (lut_base + i * 4));
        }
+
+       /* Enable the gamma table */
+       cfg_val = cfg_val | GAMMA_LUT_EN;
+
+       writel(cfg_val, regs + DISP_GAMMA_CFG);
 }
 
 void mtk_gamma_set(struct device *dev, struct drm_crtc_state *state)
-- 
2.40.1

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