Commit c18119de authored by AngeloGioacchino Del Regno's avatar AngeloGioacchino Del Regno Committed by Chun-Kuang Hu
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drm/mediatek: gamma: Improve and simplify HW LUT calculation 



Use drm_color_lut_extract() to avoid open-coding the bits reduction
calculations for each color channel and use a struct drm_color_lut
to temporarily store the information instead of an array of u32.

Also, slightly improve the precision of the HW LUT calculation in the
LUT DIFF case by performing the subtractions on the 16-bits values and
doing the 10 bits conversion later.

Reviewed-by: default avatarJason-JH.Lin <jason-jh.lin@mediatek.com>
Reviewed-by: default avatarAlexandre Mergnat <amergnat@baylibre.com>
Reviewed-by: default avatarCK Hu <ck.hu@mediatek.com>
Signed-off-by: default avatarAngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20231012095736.100784-5-angelogioacchino.delregno@collabora.com/


Signed-off-by: default avatarChun-Kuang Hu <chunkuang.hu@kernel.org>
parent d243907b

drivers/gpu/drm/mediatek/mtk_disp_gamma.c

+21 −13
Original line number Diff line number Diff line
@@ -23,8 +23,6 @@ 
#define DISP_GAMMA_SIZE				0x0030

#define DISP_GAMMA_LUT				0x0700



#define LUT_10BIT_MASK				0x03ff



struct mtk_disp_gamma_data {

	bool has_dither;

	bool lut_diff;
@@ -73,7 +71,6 @@ void mtk_gamma_set_common(struct device *dev, void __iomem *regs, struct drm_crt 
	bool lut_diff;

	u16 lut_size;

	u32 word;

	u32 diff[3] = {0};



	/* If there's no gamma lut there's nothing to do here. */

	if (!state->gamma_lut)
@@ -96,20 +93,31 @@ void mtk_gamma_set_common(struct device *dev, void __iomem *regs, struct drm_crt 
	lut_base = regs + DISP_GAMMA_LUT;

	lut = (struct drm_color_lut *)state->gamma_lut->data;

	for (i = 0; i < lut_size; i++) {

		struct drm_color_lut diff, hwlut;



		hwlut.red = drm_color_lut_extract(lut[i].red, 10);

		hwlut.green = drm_color_lut_extract(lut[i].green, 10);

		hwlut.blue = drm_color_lut_extract(lut[i].blue, 10);



		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);

			word = (hwlut.red << 20) +

			       (hwlut.green << 10) +

			       hwlut.red;

		} else {

			diff[0] = (lut[i].red >> 6) - (lut[i - 1].red >> 6);

			diff[1] = (lut[i].green >> 6) - (lut[i - 1].green >> 6);

			diff[2] = (lut[i].blue >> 6) - (lut[i - 1].blue >> 6);

			diff.red = lut[i].red - lut[i - 1].red;

			diff.red = drm_color_lut_extract(diff.red, 10);



			diff.green = lut[i].green - lut[i - 1].green;

			diff.green = drm_color_lut_extract(diff.green, 10);



			diff.blue = lut[i].blue - lut[i - 1].blue;

			diff.blue = drm_color_lut_extract(diff.blue, 10);



			word = ((diff[0] & LUT_10BIT_MASK) << 20) +

				((diff[1] & LUT_10BIT_MASK) << 10) +

				(diff[2] & LUT_10BIT_MASK);

			word = (diff.blue << 20) +

			       (diff.green << 10) +

			       diff.red;

		}

		writel(word, (lut_base + i * 4));

		writel(word, lut_base + i * 4);

	}

}