<pre>
Hi, Angelo:

On Fri, 2023-08-04 at 09:28 +0200, AngeloGioacchino Del Regno wrote:
> 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@collabora.com>
> Reviewed-by: Jason-JH.Lin <jason-jh.lin@mediatek.com>
> Reviewed-by: Alexandre Mergnat <amergnat@baylibre.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);

Move this to bottom of this function. Move here in the patch which
need.

After this modification,

Reviewed-by: CK Hu <ck.hu@mediatek.com>

> 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)

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