linux-kernel - Re: [PATCH 9/9] drm/mediatek: add dpi dual edge support

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Date:   Wed, 9 Jan 2019 17:58:44 +0100
From:   Matthias Brugger <matthias.bgg@...il.com>
To:     chunhui dai <chunhui.dai@...iatek.com>,
        --to=Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, CK Hu <ck.hu@...iatek.com>
Cc:     Philipp Zabel <p.zabel@...gutronix.de>,
        David Airlie <airlied@...ux.ie>,
        Sean Wang <sean.wang@...iatek.com>,
        Ryder Lee <ryder.lee@...iatek.com>,
        Colin Ian King <colin.king@...onical.com>,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        dri-devel@...ts.freedesktop.org, srv_heupstream@...iatek.com,
        bibby.hsieh@...iatek.com, jamesjj.liao@...iatek.com,
        jitao.shi@...iatek.com
Subject: Re: [PATCH 9/9] drm/mediatek: add dpi dual edge support



On 04/01/2019 08:03, chunhui dai wrote:
> DPI sample on rising and falling edge. It can reduce half data io.
> 
> Signed-off-by: Jitao Shi <jitao.shi@...iatek.com>
> Signed-off-by: chunhui dai <chunhui.dai@...iatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dpi.c | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c
> index 4a2f4a6..acb4f47 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> @@ -117,6 +117,7 @@ struct mtk_dpi_conf {
>  	unsigned int (*cal_factor)(int clock);
>  	u32 reg_h_fre_con;
>  	bool edge_sel_en;
> +	bool dual_edge;
>  };
>  
>  static void mtk_dpi_mask(struct mtk_dpi *dpi, u32 offset, u32 val, u32 mask)
> @@ -353,6 +354,15 @@ 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_config_dual_edge(struct mtk_dpi *dpi)

I think it is clearer if you rename the function to something like:
mtk_dpi_enable_dual_edge and call it in mtk_dpi_set_display_mode if
dpi->conf->dual_edge is true.

Regards,
Matthias

> +{
> +	if (dpi->conf->dual_edge) {
> +		mtk_dpi_mask(dpi, DPI_DDR_SETTING, DDR_EN |
> +				DDR_4PHASE, DDR_EN | DDR_4PHASE);
> +		mtk_dpi_mask(dpi, DPI_OUTPUT_SETTING, EDGE_SEL, EDGE_SEL);
> +	}
> +}
> +
>  static void mtk_dpi_config_color_format(struct mtk_dpi *dpi,
>  					enum mtk_dpi_out_color_format format)
>  {
> @@ -509,6 +519,7 @@ static int mtk_dpi_set_display_mode(struct mtk_dpi *dpi,
>  	mtk_dpi_config_color_format(dpi, dpi->color_format);
>  	mtk_dpi_config_2n_h_fre(dpi);
>  	mtk_dpi_config_disable_edge(dpi);
> +	mtk_dpi_config_dual_edge(dpi);
>  	mtk_dpi_sw_reset(dpi, false);
>  
>  	return 0;
> @@ -669,6 +680,16 @@ static unsigned int mt2701_calculate_factor(int clock)
>  		return 1;
>  }
>  
> +static unsigned int mt8183_calculate_factor(int clock)
> +{
> +	if (clock <= 27000)
> +		return 8;
> +	else if (clock <= 167000)
> +		return 4;
> +	else
> +		return 2;
> +}
> +
>  static const struct mtk_dpi_conf mt8173_conf = {
>  	.cal_factor = mt8173_calculate_factor,
>  	.reg_h_fre_con = 0xe0,
> @@ -680,6 +701,12 @@ static unsigned int mt2701_calculate_factor(int clock)
>  	.edge_sel_en = true,
>  };
>  
> +static const struct mtk_dpi_conf mt8183_conf = {
> +	.cal_factor = mt8183_calculate_factor,
> +	.reg_h_fre_con = 0xe0,
> +	.dual_edge = true,
> +};
> +
>  static int mtk_dpi_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -775,6 +802,9 @@ static int mtk_dpi_remove(struct platform_device *pdev)
>  	{ .compatible = "mediatek,mt8173-dpi",
>  	  .data = &mt8173_conf,
>  	},
> +	{ .compatible = "mediatek,mt8183-dpi",
> +	  .data = &mt8183_conf,
> +	},
>  	{ },
>  };
>  
>