linux-kernel - [PATCH RESEND v6 04/11] drm/mediatek: gamma: Improve and simplify HW LUT calculation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230727094633.22505-5-angelogioacchino.delregno@collabora.com>
Date:   Thu, 27 Jul 2023 11:46:26 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     chunkuang.hu@...nel.org
Cc:     p.zabel@...gutronix.de, airlied@...il.com, daniel@...ll.ch,
        matthias.bgg@...il.com, angelogioacchino.delregno@...labora.com,
        dri-devel@...ts.freedesktop.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, wenst@...omium.org,
        kernel@...labora.com, ehristev@...labora.com,
        "Jason-JH . Lin" <jason-jh.lin@...iatek.com>
Subject: [PATCH RESEND v6 04/11] 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.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Reviewed-by: Jason-JH.Lin <jason-jh.lin@...iatek.com>
---
 drivers/gpu/drm/mediatek/mtk_disp_gamma.c | 30 +++++++++++++++--------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
index b25ba209e7a4..204a1aa7bfc9 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
@@ -77,7 +77,6 @@ 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)
@@ -97,18 +96,29 @@ 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));
 	}
-- 
2.40.1