Re: [PATCH v15 13/16] drm/mediatek: dpi: Add YUV422 output support

[CK Hu <ck.hu@mediatek.com>]

Hi, Bo-Chen:

On Fri, 2022-07-01 at 11:58 +0800, Bo-Chen Chen wrote:
> Dp_intf supports YUV422 as output format. In MT8195 Chrome project,
> YUV422 output format is used for 4K resolution.
> 
> To support this, it is also needed to support color format transfer.
> Color format transfer is a new feature for both dpi and dpintf of
> MT8195.
> 
> The input format could be RGB888 and output format for dp_intf should
> be
> YUV422. Therefore, we add a mtk_dpi_matrix_sel() helper to update the
> DPI_MATRIX_SET register depending on the color format.
> 
> Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
> Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
> Reviewed-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@collabora.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dpi.c      | 61 +++++++++++++++++++++
> ----
>  drivers/gpu/drm/mediatek/mtk_dpi_regs.h |  6 +++
>  2 files changed, 59 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c
> b/drivers/gpu/drm/mediatek/mtk_dpi.c
> index 3085033becbd..0a604bf68b1b 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> @@ -54,7 +54,8 @@ enum mtk_dpi_out_channel_swap {
>  };
>  
>  enum mtk_dpi_out_color_format {
> -	MTK_DPI_COLOR_FORMAT_RGB
> +	MTK_DPI_COLOR_FORMAT_RGB,
> +	MTK_DPI_COLOR_FORMAT_YCBCR_422
>  };
>  
>  struct mtk_dpi {
> @@ -122,6 +123,7 @@ struct mtk_dpi_yc_limit {
>   * @num_output_fmts: Quantity of supported output formats.
>   * @is_ck_de_pol: Support CK/DE polarity.
>   * @swap_input_support: Support input swap function.
> + * @color_fmt_trans_support: Enable color format transfer.
>   * @dimension_mask: Mask used for HWIDTH, HPORCH, VSYNC_WIDTH and
> VSYNC_PORCH
>   *		    (no shift).
>   * @hvsize_mask: Mask of HSIZE and VSIZE mask (no shift).
> @@ -138,6 +140,7 @@ struct mtk_dpi_conf {
>  	u32 num_output_fmts;
>  	bool is_ck_de_pol;
>  	bool swap_input_support;
> +	bool color_fmt_trans_support;
>  	u32 dimension_mask;
>  	u32 hvsize_mask;
>  	u32 channel_swap_shift;
> @@ -406,15 +409,54 @@ 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)

The format would only be MTK_DPI_COLOR_FORMAT_YCBCR_422, so drop the
parameter format.

> +{
> +	u32 matrix_sel;
> +
> +	if (!dpi->conf->color_fmt_trans_support) {

Only YUV format would call this function, and I think YUV support would
imply that color_fmt_trans_support is true. So drop
color_fmt_trans_support.

> +		dev_info(dpi->dev, "matrix_sel is not supported.\n");
> +		return;
> +	}
> +
> +	switch (format) {
> +	case MTK_DPI_COLOR_FORMAT_YCBCR_422:
> +		/*
> +		 * If height is smaller than 720, we need to use
> RGB_TO_BT601
> +		 * to transfer to yuv422. Otherwise, we use
> RGB_TO_JPEG.
> +		 */
> +		if (dpi->mode.hdisplay <= 720)
> +			matrix_sel = MATRIX_SEL_RGB_TO_BT601;
> +		else
> +			matrix_sel = MATRIX_SEL_RGB_TO_JPEG;
> +		break;
> +	default:
> +		matrix_sel = MATRIX_SEL_RGB_TO_JPEG;
> +		break;
> +	}
> +	mtk_dpi_mask(dpi, DPI_MATRIX_SET, matrix_sel,
> INT_MATRIX_SEL_MASK);

it seems that we could drop this function and write register as:

mtk_dpi_mask(dpi, DPI_MATRIX_SET, dpi->mode.hdisplay <= 720
? MATRIX_SEL_RGB_TO_BT601 : MATRIX_SEL_RGB_TO_JPEG,
INT_MATRIX_SEL_MASK);

> +}
> +
>  static void mtk_dpi_config_color_format(struct mtk_dpi *dpi,
>  					enum mtk_dpi_out_color_format
> format)
>  {
> -	/* only support RGB888 */
> -	mtk_dpi_config_yuv422_enable(dpi, false);
> -	mtk_dpi_config_csc_enable(dpi, false);
> -	if (dpi->conf->swap_input_support)
> -		mtk_dpi_config_swap_input(dpi, false);
> -	mtk_dpi_config_channel_swap(dpi, MTK_DPI_OUT_CHANNEL_SWAP_RGB);
> +	if (format == MTK_DPI_COLOR_FORMAT_YCBCR_422) {
> +		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)

This would never be true because only MT8195 support
MTK_DPI_COLOR_FORMAT_YCBCR_422 and swap_input_support of MT8195 is
false.

Regards,
CK

> +			mtk_dpi_config_swap_input(dpi, true);
> +		else
> +			dev_warn(dpi->dev,
> +				 "Failed to swap input, hw is not
> supported.\n");
> +		mtk_dpi_config_channel_swap(dpi,
> MTK_DPI_OUT_CHANNEL_SWAP_RGB);
> +	} else {
> +		mtk_dpi_config_yuv422_enable(dpi, false);
> +		mtk_dpi_config_csc_enable(dpi, false);
> +		if (dpi->conf->swap_input_support)
> +			mtk_dpi_config_swap_input(dpi, false);
> +		mtk_dpi_config_channel_swap(dpi,
> MTK_DPI_OUT_CHANNEL_SWAP_RGB);
> +	}
>  }
>  
>  static void mtk_dpi_dual_edge(struct mtk_dpi *dpi)
> @@ -649,7 +691,10 @@ static int mtk_dpi_bridge_atomic_check(struct
> drm_bridge *bridge,
>  	dpi->bit_num = MTK_DPI_OUT_BIT_NUM_8BITS;
>  	dpi->channel_swap = MTK_DPI_OUT_CHANNEL_SWAP_RGB;
>  	dpi->yc_map = MTK_DPI_OUT_YC_MAP_RGB;
> -	dpi->color_format = MTK_DPI_COLOR_FORMAT_RGB;
> +	if (out_bus_format == MEDIA_BUS_FMT_YUYV8_1X16)
> +		dpi->color_format = MTK_DPI_COLOR_FORMAT_YCBCR_422;
> +	else
> +		dpi->color_format = MTK_DPI_COLOR_FORMAT_RGB;
>  
>  	return 0;
>  }
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi_regs.h
> b/drivers/gpu/drm/mediatek/mtk_dpi_regs.h
> index 3a02fabe1662..9ce300313f3e 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi_regs.h
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi_regs.h
> @@ -217,4 +217,10 @@
>  
>  #define EDGE_SEL_EN			BIT(5)
>  #define H_FRE_2N			BIT(25)
> +
> +#define DPI_MATRIX_SET		0xB4
> +#define INT_MATRIX_SEL_MASK		GENMASK(4, 0)
> +#define MATRIX_SEL_RGB_TO_JPEG		0
> +#define MATRIX_SEL_RGB_TO_BT601		2
> +
>  #endif /* __MTK_DPI_REGS_H */