drm/mediatek: Fix YCbCr422 color format issue for DP

[ Upstream commit ef24fbd8f12015ff827973fffefed3902ffd61cc ]

Setting up misc0 for Pixel Encoding Format.

According to the definition of YCbCr in spec 1.2a Table 2-96,
0x1 << 1 should be written to the register.

Use switch case to distinguish RGB, YCbCr422,
and unsupported color formats.

Fixes: f70ac097a2cf ("drm/mediatek: Add MT8195 Embedded DisplayPort driver")
Signed-off-by: Liankun Yang <liankun.yang@mediatek.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20241025083036.8829-2-liankun.yang@mediatek.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index c24eeb7ffde7d744b66587d80c6b10ae27945bff..04e3f72fa2324c17d4a695d8847fcf8c087c0d5a 100644 (file)
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -457,18 +457,16 @@ static int mtk_dp_set_color_format(struct mtk_dp *mtk_dp,
                                   enum dp_pixelformat color_format)
 {
        u32 val;
-
-       /* update MISC0 */
-       mtk_dp_update_bits(mtk_dp, MTK_DP_ENC0_P0_3034,
-                          color_format << DP_TEST_COLOR_FORMAT_SHIFT,
-                          DP_TEST_COLOR_FORMAT_MASK);
+       u32 misc0_color;
 
        switch (color_format) {
        case DP_PIXELFORMAT_YUV422:
                val = PIXEL_ENCODE_FORMAT_DP_ENC0_P0_YCBCR422;
+               misc0_color = DP_COLOR_FORMAT_YCbCr422;
                break;
        case DP_PIXELFORMAT_RGB:
                val = PIXEL_ENCODE_FORMAT_DP_ENC0_P0_RGB;
+               misc0_color = DP_COLOR_FORMAT_RGB;
                break;
        default:
                drm_warn(mtk_dp->drm_dev, "Unsupported color format: %d\n",
@@ -476,6 +474,11 @@ static int mtk_dp_set_color_format(struct mtk_dp *mtk_dp,
                return -EINVAL;
        }
 
+       /* update MISC0 */
+       mtk_dp_update_bits(mtk_dp, MTK_DP_ENC0_P0_3034,
+                          misc0_color,
+                          DP_TEST_COLOR_FORMAT_MASK);
+
        mtk_dp_update_bits(mtk_dp, MTK_DP_ENC0_P0_303C,
                           val, PIXEL_ENCODE_FORMAT_DP_ENC0_P0_MASK);
        return 0;