linux-kernel - Re: [PATCH] drm/mediatek: add mt8183 dpi support

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Message-ID: <20190214204149.GO114153@art_vandelay>
Date:   Thu, 14 Feb 2019 15:41:49 -0500
From:   Sean Paul <sean@...rly.run>
To:     Jitao Shi <jitao.shi@...iatek.com>
Cc:     Rob Herring <robh+dt@...nel.org>, Pawel Moll <pawel.moll@....com>,
        Mark Rutland <mark.rutland@....com>,
        Ian Campbell <ijc+devicetree@...lion.org.uk>,
        Kumar Gala <galak@...eaurora.org>, linux-pwm@...r.kernel.org,
        David Airlie <airlied@...ux.ie>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Thierry Reding <treding@...dia.com>,
        Ajay Kumar <ajaykumar.rs@...sung.com>,
        Inki Dae <inki.dae@...sung.com>,
        Rahul Sharma <rahul.sharma@...sung.com>,
        Sean Paul <seanpaul@...omium.org>,
        Vincent Palatin <vpalatin@...omium.org>,
        Andy Yan <andy.yan@...k-chips.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Russell King <rmk+kernel@....linux.org.uk>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, srv_heupstream@...iatek.com,
        Sascha Hauer <kernel@...gutronix.de>,
        yingjoe.chen@...iatek.com, eddie.huang@...iatek.com,
        cawa.cheng@...iatek.com, bibby.hsieh@...iatek.com,
        ck.hu@...iatek.com, stonea168@....com
Subject: Re: [PATCH] drm/mediatek: add mt8183 dpi support

On Mon, Feb 11, 2019 at 12:50:59PM +0800, Jitao Shi wrote:
> MT8183 sample on rising and falling edge. It can reduce half data io.
> 
> Signed-off-by: Jitao Shi <jitao.shi@...iatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dpi.c | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c
> index 62a9d47df948..610c23334047 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 +354,13 @@ 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_enable_dual_edge(struct mtk_dpi *dpi)
> +{
> +	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 +517,8 @@ 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);
> +	if (dpi->conf->dual_edge)
> +		mtk_dpi_enable_dual_edge(dpi);
>  	mtk_dpi_sw_reset(dpi, false);
>  
>  	return 0;
> @@ -671,6 +681,16 @@ static unsigned int mt2701_calculate_factor(int clock)
>  		return 2;
>  }
>  
> +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,
> @@ -682,6 +702,12 @@ static const struct mtk_dpi_conf mt2701_conf = {
>  	.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;
> @@ -777,6 +803,9 @@ static const struct of_device_id mtk_dpi_of_ids[] = {
>  	{ .compatible = "mediatek,mt8173-dpi",
>  	  .data = &mt8173_conf,
>  	},
> +	{ .compatible = "mediatek,mt8183-dpi",

Do you need to add this compatible value to the dt binding? If you can do as CK
suggested, maybe you don't need this at all (and mt8183 can use the mt8173
compatible string in the dt).

Sean

> +	  .data = &mt8183_conf,
> +	},
>  	{ },
>  };
>  
> -- 
> 2.12.5
> 

-- 
Sean Paul, Software Engineer, Google / Chromium OS