linux-kernel - Re: [PATCH v12 14/14] drm/mediatek: dpi: Add matrix

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Date:   Tue, 21 Jun 2022 11:33:15 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     Bo-Chen Chen <rex-bc.chen@...iatek.com>, <chunkuang.hu@...nel.org>,
        <p.zabel@...gutronix.de>, <daniel@...ll.ch>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <matthias.bgg@...il.com>,
        <airlied@...ux.ie>
CC:     <msp@...libre.com>, <granquet@...libre.com>,
        <jitao.shi@...iatek.com>, <wenst@...omium.org>,
        <angelogioacchino.delregno@...labora.com>,
        <dri-devel@...ts.freedesktop.org>,
        <linux-mediatek@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <Project_Global_Chrome_Upstream_Group@...iatek.com>
Subject: Re: [PATCH v12 14/14] drm/mediatek: dpi: Add matrix_sel helper

Hi, Bo-Chen:

On Mon, 2022-06-20 at 20:10 +0800, Bo-Chen Chen wrote:
> From: Guillaume Ranquet <granquet@...libre.com>
> 
> Matrix selection is a new feature for both dpi and dpintf of MT8195.
> Add a mtk_dpi_matrix_sel() helper to update the DPI_MATRIX_SET
> register depending on the color format.

Describe more about what this do.

> 
> Signed-off-by: Guillaume Ranquet <granquet@...libre.com>
> Signed-off-by: Bo-Chen Chen <rex-bc.chen@...iatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dpi.c      | 29
> +++++++++++++++++++++++++
>  drivers/gpu/drm/mediatek/mtk_dpi_regs.h |  3 +++
>  2 files changed, 32 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c
> b/drivers/gpu/drm/mediatek/mtk_dpi.c
> index 220e9b18e2cd..8a9151cb1622 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> @@ -135,6 +135,7 @@ struct mtk_dpi_conf {
>  	u32 channel_swap_shift;
>  	u32 yuv422_en_bit;
>  	u32 csc_enable_bit;
> +	bool matrx_sel_support;
>  };
>  
>  static void mtk_dpi_mask(struct mtk_dpi *dpi, u32 offset, u32 val,
> u32 mask)
> @@ -398,6 +399,31 @@ static void mtk_dpi_config_disable_edge(struct
> mtk_dpi *dpi)
>  		mtk_dpi_mask(dpi, dpi->conf->reg_h_fre_con, 0,
> EDGE_SEL_EN);
>  }
>  
> +static void mtk_dpi_matrix_sel(struct mtk_dpi *dpi,
> +			       enum mtk_dpi_out_color_format format)
> +{
> +	u32 matrix_sel = 0;
> +
> +	if (!dpi->conf->matrx_sel_support) {
> +		dev_info(dpi->dev, "matrix_sel is not supported.\n");

So for this SoC, there would be something wrong? I still does not
understand what this feature is.

static const struct of_device_id mtk_dpi_of_ids[] = {
	{ .compatible = "mediatek,mt2701-dpi",
	  .data = &mt2701_conf,
	},
	{ .compatible = "mediatek,mt8173-dpi",
	  .data = &mt8173_conf,
	},
	{ .compatible = "mediatek,mt8183-dpi",
	  .data = &mt8183_conf,
	},
	{ .compatible = "mediatek,mt8192-dpi",
	  .data = &mt8192_conf,
	},
	{ },
};

> +		return;
> +	}
> +
> +	switch (format) {
> +	case MTK_DPI_COLOR_FORMAT_YCBCR_422:
> +	case MTK_DPI_COLOR_FORMAT_YCBCR_422_FULL:
> +	case MTK_DPI_COLOR_FORMAT_YCBCR_444:
> +	case MTK_DPI_COLOR_FORMAT_YCBCR_444_FULL:
> +	case MTK_DPI_COLOR_FORMAT_XV_YCC:
> +		if (dpi->mode.hdisplay <= 720)
> +			matrix_sel = 0x2;

Symbolize 0x2.

> +		break;
> +	default:

If format is MTK_DPI_COLOR_FORMAT_YCBCR_422 first, then format change
to MTK_DPI_COLOR_FORMAT_RGB and matrix_sel would still be 0x2. Is this
correct?

Regards,
CK

> +		break;
> +	}
> +	mtk_dpi_mask(dpi, DPI_MATRIX_SET, matrix_sel,
> INT_MATRIX_SEL_MASK);
> +}
> +
>  static void mtk_dpi_config_color_format(struct mtk_dpi *dpi,
>  					enum mtk_dpi_out_color_format
> format)
>  {
> @@ -405,6 +431,7 @@ static void mtk_dpi_config_color_format(struct
> mtk_dpi *dpi,
>  	    (format == MTK_DPI_COLOR_FORMAT_YCBCR_444_FULL)) {
>  		mtk_dpi_config_yuv422_enable(dpi, false);
>  		mtk_dpi_config_csc_enable(dpi, true);
> +		mtk_dpi_matrix_sel(dpi, format);
>  		if (dpi->conf->swap_input_support)
>  			mtk_dpi_config_swap_input(dpi, false);
>  		mtk_dpi_config_channel_swap(dpi,
> MTK_DPI_OUT_CHANNEL_SWAP_BGR);
> @@ -412,6 +439,7 @@ static void mtk_dpi_config_color_format(struct
> mtk_dpi *dpi,
>  		   (format == MTK_DPI_COLOR_FORMAT_YCBCR_422_FULL)) {
>  		mtk_dpi_config_yuv422_enable(dpi, true);
>  		mtk_dpi_config_csc_enable(dpi, true);
> +		mtk_dpi_matrix_sel(dpi, format);
>  		if (dpi->conf->swap_input_support)
>  			mtk_dpi_config_swap_input(dpi, true);
>  		else
> @@ -951,6 +979,7 @@ static const struct mtk_dpi_conf
> mt8195_dpintf_conf = {
>  	.channel_swap_shift = DPINTF_CH_SWAP,
>  	.yuv422_en_bit = DPINTF_YUV422_EN,
>  	.csc_enable_bit = DPINTF_CSC_ENABLE,
> +	.matrx_sel_support = true,
>  };
>  
>  static int mtk_dpi_probe(struct platform_device *pdev)
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi_regs.h
> b/drivers/gpu/drm/mediatek/mtk_dpi_regs.h
> index f7f0272dbd6a..96c117202d0d 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi_regs.h
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi_regs.h
> @@ -230,4 +230,7 @@
>  #define EDGE_SEL_EN			BIT(5)
>  #define H_FRE_2N			BIT(25)
>  
> +#define DPI_MATRIX_SET		0xB4
> +#define INT_MATRIX_SEL_MASK	(0x1F << 0)
> +
>  #endif /* __MTK_DPI_REGS_H */