linux-kernel - Re: [PATCH v8 07/13] drm/mediatek: gamma: Support specifying number of bits per LUT component

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Date:   Wed, 2 Aug 2023 04:03:36 +0000
From:   CK Hu (胡俊光) <ck.hu@...iatek.com>
To:     "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>,
        "chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>
CC:     "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "wenst@...omium.org" <wenst@...omium.org>,
        Jason-JH Lin (林睿祥) 
        <Jason-JH.Lin@...iatek.com>,
        "kernel@...labora.com" <kernel@...labora.com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "amergnat@...libre.com" <amergnat@...libre.com>,
        "ehristev@...labora.com" <ehristev@...labora.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>
Subject: Re: [PATCH v8 07/13] drm/mediatek: gamma: Support specifying number
 of bits per LUT component

Hi, Angelo:

On Tue, 2023-08-01 at 13:58 +0200, AngeloGioacchino Del Regno wrote:
> 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@...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 | 23 +++++++++++++++----
> ----
>  1 file changed, 15 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
> b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
> index 4f642fed432f..a6f7af1a9e8e 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
> @@ -37,6 +37,7 @@ struct mtk_disp_gamma_data {
>  	bool has_dither;
>  	bool lut_diff;
>  	u16 lut_size;
> +	u8 lut_bits;
>  };
>  
>  /*
> @@ -78,6 +79,7 @@ void mtk_gamma_set_common(struct device *dev, void
> __iomem *regs,
>  	struct drm_color_lut *lut;
>  	void __iomem *lut_base;
>  	bool lut_diff;
> +	u8 lut_bits;
>  	u32 cfg_val, word;
>  
>  	/* If there's no gamma lut there's nothing to do here. */
> @@ -87,10 +89,13 @@ void mtk_gamma_set_common(struct device *dev,
> void __iomem *regs,
>  	/* If we're called from AAL, dev is NULL */
>  	gamma = dev ? dev_get_drvdata(dev) : NULL;
>  
> -	if (gamma && gamma->data)
> +	if (gamma && gamma->data) {
>  		lut_diff = gamma->data->lut_diff;
> -	else
> +		lut_bits = gamma->data->lut_bits;
> +	} else {
>  		lut_diff = false;
> +		lut_bits = LUT_BITS_DEFAULT;

LUT_BITS_DEFAULT is only for AAL driver, so place this definition in
AAL driver and pass it into this function.

Regards,
CK

> +	}
>  
>  	cfg_val = readl(regs + DISP_GAMMA_CFG);
>  	lut_base = regs + DISP_GAMMA_LUT;
> @@ -98,9 +103,9 @@ void mtk_gamma_set_common(struct device *dev, void
> __iomem *regs,
>  	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.blue = 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.blue = 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);
> @@ -108,13 +113,13 @@ void mtk_gamma_set_common(struct device *dev,
> void __iomem *regs,
>  			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);
> @@ -231,10 +236,12 @@ 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,
>  };