linux-kernel - [PATCH v7 05/13] drm/mediatek: gamma: Enable the Gamma LUT table only after programming

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: <20230731130441.173960-6-angelogioacchino.delregno@collabora.com>
Date:   Mon, 31 Jul 2023 15:04:33 +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>,
        Alexandre Mergnat <amergnat@...libre.com>
Subject: [PATCH v7 05/13] drm/mediatek: gamma: Enable the Gamma LUT table only after programming

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.

Note:
GAMMA should get enabled in between vblanks, but this requires many
efforts in order to make this happen, as that requires migrating all
of the writes to make use of CMDQ instead of cpu writes and that's
not trivial. For this reason, this patch only moves the LUT enable.
The CMDQ rework will come at a later time.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Reviewed-by: Jason-JH.Lin <jason-jh.lin@...iatek.com>
Reviewed-by: Alexandre Mergnat <amergnat@...libre.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 fd6a75a64a9f..18b102bef370 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
@@ -68,12 +68,12 @@ 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;
-	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)
-- 
2.41.0