[PATCH 07/11] drm/mediatek: gamma: Support specifying number of bits per LUT component

[AngeloGioacchino Del Regno]

New SoCs, like MT8195, not only may support bigger lookup tables, but
have got a different register layout to support bigger precision:
support specifying the number of `lut_bits` for each SoC and use it
in mtk_gamma_set_common() to perform the right calculation.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno at collabora.com>
---
 drivers/gpu/drm/mediatek/mtk_disp_gamma.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
index ef0243034663..320a7e36d9c5 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
@@ -38,6 +38,7 @@ struct mtk_disp_gamma_data {
 	bool has_dither;
 	bool lut_diff;
 	u16 lut_size;
+	u8 lut_bits;
 };
 
 /*
@@ -83,6 +84,7 @@ void mtk_gamma_set_common(struct device *dev, void __iomem *regs, struct drm_crt
 	void __iomem *lut_base;
 	bool lut_diff;
 	u16 lut_size;
+	u8 lut_bits;
 	u32 cfg_val, word;
 
 	/* If there's no gamma lut there's nothing to do here. */
@@ -91,9 +93,11 @@ void mtk_gamma_set_common(struct device *dev, void __iomem *regs, struct drm_crt
 
 	if (gamma && gamma->data) {
 		lut_diff = gamma->data->lut_diff;
+		lut_bits = gamma->data->lut_bits;
 		lut_size = gamma->data->lut_size;
 	} else {
 		lut_diff = false;
+		lut_bits = LUT_BITS_DEFAULT;
 		lut_size = LUT_SIZE_DEFAULT;
 	}
 
@@ -103,9 +107,9 @@ void mtk_gamma_set_common(struct device *dev, void __iomem *regs, struct drm_crt
 	for (i = 0; i < lut_size; i++) {
 		struct drm_color_lut diff, hwlut;
 
-		hwlut.red = drm_color_lut_extract(lut[i].red, LUT_BITS_DEFAULT);
-		hwlut.green = drm_color_lut_extract(lut[i].green, LUT_BITS_DEFAULT);
-		hwlut.red = drm_color_lut_extract(lut[i].blue, LUT_BITS_DEFAULT);
+		hwlut.red = drm_color_lut_extract(lut[i].red, lut_bits);
+		hwlut.green = drm_color_lut_extract(lut[i].green, lut_bits);
+		hwlut.red = drm_color_lut_extract(lut[i].blue, lut_bits);
 
 		if (!lut_diff || (i % 2 == 0)) {
 			word = FIELD_PREP(DISP_GAMMA_LUT_10BIT_R, hwlut.red);
@@ -113,13 +117,13 @@ void mtk_gamma_set_common(struct device *dev, void __iomem *regs, struct drm_crt
 			word |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_B, hwlut.blue);
 		} else {
 			diff.red = lut[i].red - lut[i - 1].red;
-			diff.red = drm_color_lut_extract(diff.red, LUT_BITS_DEFAULT);
+			diff.red = drm_color_lut_extract(diff.red, lut_bits);
 
 			diff.green = lut[i].green - lut[i - 1].green;
-			diff.green = drm_color_lut_extract(diff.green, LUT_BITS_DEFAULT);
+			diff.green = drm_color_lut_extract(diff.green, lut_bits);
 
 			diff.blue = lut[i].blue - lut[i - 1].blue;
-			diff.blue = drm_color_lut_extract(diff.blue, LUT_BITS_DEFAULT);
+			diff.blue = drm_color_lut_extract(diff.blue, lut_bits);
 
 			word = FIELD_PREP(DISP_GAMMA_LUT_10BIT_R, diff.red);
 			word |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_G, diff.green);
@@ -236,10 +240,12 @@ static int mtk_disp_gamma_remove(struct platform_device *pdev)
 
 static const struct mtk_disp_gamma_data mt8173_gamma_driver_data = {
 	.has_dither = true,
+	.lut_bits = 10,
 	.lut_size = 512,
 };
 
 static const struct mtk_disp_gamma_data mt8183_gamma_driver_data = {
+	.lut_bits = 10,
 	.lut_diff = true,
 	.lut_size = 512,
 };
-- 
2.40.1