linux-kernel - Re: [PATCH v11 02/12] drm/mediatek: dpi: move dpi limits to SoC config

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Message-ID: <5de2752a1d496290ea5c2c2d7840ba984b2e7e4d.camel@mediatek.com>
Date:   Tue, 14 Jun 2022 11:21:46 +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 v11 02/12] drm/mediatek: dpi: move dpi limits to SoC
 config

Hi, Bo-Chen:

On Mon, 2022-06-13 at 14:48 +0800, Bo-Chen Chen wrote:
> From: Guillaume Ranquet <granquet@...libre.com>
> 
> Add flexibility by moving the dpi limits to the SoC specific config.

What does this 'limit' mean? Why it's different in DPI vs DP_INTF?

The hardware design is so weird. If the limit is fixed for DPI and
DP_INTF, why the hardware export register for software to assign any
value which may be wrong.

Regards,
CK

> 
> Signed-off-by: Guillaume Ranquet <granquet@...libre.com>
> Signed-off-by: Bo-Chen Chen <rex-bc.chen@...iatek.com>
> Reviewed-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@...labora.com>
> Reviewed-by: Rex-BC Chen <rex-bc.chen@...iatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dpi.c | 25 ++++++++++++++++---------
>  1 file changed, 16 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c
> b/drivers/gpu/drm/mediatek/mtk_dpi.c
> index e61cd67b978f..ce8c5eefe5f1 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> @@ -125,6 +125,7 @@ struct mtk_dpi_conf {
>  	bool edge_sel_en;
>  	const u32 *output_fmts;
>  	u32 num_output_fmts;
> +	const struct mtk_dpi_yc_limit *limit;
>  };
>  
>  static void mtk_dpi_mask(struct mtk_dpi *dpi, u32 offset, u32 val,
> u32 mask)
> @@ -235,9 +236,10 @@ static void mtk_dpi_config_fb_size(struct
> mtk_dpi *dpi, u32 width, u32 height)
>  	mtk_dpi_mask(dpi, DPI_SIZE, height << VSIZE, VSIZE_MASK);
>  }
>  
> -static void mtk_dpi_config_channel_limit(struct mtk_dpi *dpi,
> -					 struct mtk_dpi_yc_limit
> *limit)
> +static void mtk_dpi_config_channel_limit(struct mtk_dpi *dpi)
>  {
> +	const struct mtk_dpi_yc_limit *limit = dpi->conf->limit;
> +
>  	mtk_dpi_mask(dpi, DPI_Y_LIMIT, limit->y_bottom << Y_LIMINT_BOT,
>  		     Y_LIMINT_BOT_MASK);
>  	mtk_dpi_mask(dpi, DPI_Y_LIMIT, limit->y_top << Y_LIMINT_TOP,
> @@ -449,7 +451,6 @@ static int mtk_dpi_power_on(struct mtk_dpi *dpi)
>  static int mtk_dpi_set_display_mode(struct mtk_dpi *dpi,
>  				    struct drm_display_mode *mode)
>  {
> -	struct mtk_dpi_yc_limit limit;
>  	struct mtk_dpi_polarities dpi_pol;
>  	struct mtk_dpi_sync_param hsync;
>  	struct mtk_dpi_sync_param vsync_lodd = { 0 };
> @@ -484,11 +485,6 @@ static int mtk_dpi_set_display_mode(struct
> mtk_dpi *dpi,
>  	dev_dbg(dpi->dev, "Got  PLL %lu Hz, pixel clock %lu Hz\n",
>  		pll_rate, vm.pixelclock);
>  
> -	limit.c_bottom = 0x0010;
> -	limit.c_top = 0x0FE0;
> -	limit.y_bottom = 0x0010;
> -	limit.y_top = 0x0FE0;
> -
>  	dpi_pol.ck_pol = MTK_DPI_POLARITY_FALLING;
>  	dpi_pol.de_pol = MTK_DPI_POLARITY_RISING;
>  	dpi_pol.hsync_pol = vm.flags & DISPLAY_FLAGS_HSYNC_HIGH ?
> @@ -536,7 +532,7 @@ static int mtk_dpi_set_display_mode(struct
> mtk_dpi *dpi,
>  	else
>  		mtk_dpi_config_fb_size(dpi, vm.hactive, vm.vactive);
>  
> -	mtk_dpi_config_channel_limit(dpi, &limit);
> +	mtk_dpi_config_channel_limit(dpi);
>  	mtk_dpi_config_bit_num(dpi, dpi->bit_num);
>  	mtk_dpi_config_channel_swap(dpi, dpi->channel_swap);
>  	mtk_dpi_config_yc_map(dpi, dpi->yc_map);
> @@ -790,12 +786,20 @@ static const u32 mt8183_output_fmts[] = {
>  	MEDIA_BUS_FMT_RGB888_2X12_BE,
>  };
>  
> +static const struct mtk_dpi_yc_limit mtk_dpi_limit = {
> +	.c_bottom = 0x0010,
> +	.c_top = 0x0FE0,
> +	.y_bottom = 0x0010,
> +	.y_top = 0x0FE0,
> +};
> +
>  static const struct mtk_dpi_conf mt8173_conf = {
>  	.cal_factor = mt8173_calculate_factor,
>  	.reg_h_fre_con = 0xe0,
>  	.max_clock_khz = 300000,
>  	.output_fmts = mt8173_output_fmts,
>  	.num_output_fmts = ARRAY_SIZE(mt8173_output_fmts),
> +	.limit = &mtk_dpi_limit,
>  };
>  
>  static const struct mtk_dpi_conf mt2701_conf = {
> @@ -805,6 +809,7 @@ static const struct mtk_dpi_conf mt2701_conf = {
>  	.max_clock_khz = 150000,
>  	.output_fmts = mt8173_output_fmts,
>  	.num_output_fmts = ARRAY_SIZE(mt8173_output_fmts),
> +	.limit = &mtk_dpi_limit,
>  };
>  
>  static const struct mtk_dpi_conf mt8183_conf = {
> @@ -813,6 +818,7 @@ static const struct mtk_dpi_conf mt8183_conf = {
>  	.max_clock_khz = 100000,
>  	.output_fmts = mt8183_output_fmts,
>  	.num_output_fmts = ARRAY_SIZE(mt8183_output_fmts),
> +	.limit = &mtk_dpi_limit,
>  };
>  
>  static const struct mtk_dpi_conf mt8192_conf = {
> @@ -821,6 +827,7 @@ static const struct mtk_dpi_conf mt8192_conf = {
>  	.max_clock_khz = 150000,
>  	.output_fmts = mt8183_output_fmts,
>  	.num_output_fmts = ARRAY_SIZE(mt8183_output_fmts),
> +	.limit = &mtk_dpi_limit,
>  };
>  
>  static int mtk_dpi_probe(struct platform_device *pdev)