linux-kernel - Re: [PATCH v7 4/4] drm/mediatek: set dpi pin mode to gpio low to avoid leakage current

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Message-ID: <1582615985.30857.5.camel@mtksdaap41>
Date:   Tue, 25 Feb 2020 15:33:05 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     Jitao Shi <jitao.shi@...iatek.com>
CC:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <srv_heupstream@...iatek.com>, <yingjoe.chen@...iatek.com>,
        <eddie.huang@...iatek.com>, <cawa.cheng@...iatek.com>,
        <bibby.hsieh@...iatek.com>, <stonea168@....com>,
        <huijuan.xie@...iatek.com>
Subject: Re: [PATCH v7 4/4] drm/mediatek: set dpi pin mode to gpio low to
 avoid leakage current

Hi, Jitao:

On Tue, 2020-02-25 at 14:46 +0800, Jitao Shi wrote:
> Config dpi pins mode to output and pull low when dpi is disabled.
> Aovid leakage current from some dpi pins (Hsync Vsync DE ... ).
> 
> Signed-off-by: Jitao Shi <jitao.shi@...iatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dpi.c | 33 ++++++++++++++++++++++++++++--
>  1 file changed, 31 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c
> index c3e631b93c2e..ca570040ffdf 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> @@ -10,7 +10,9 @@
>  #include <linux/kernel.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> +#include <linux/of_gpio.h>
>  #include <linux/of_graph.h>
> +#include <linux/pinctrl/consumer.h>
>  #include <linux/platform_device.h>
>  #include <linux/types.h>
>  
> @@ -74,6 +76,9 @@ struct mtk_dpi {
>  	enum mtk_dpi_out_yc_map yc_map;
>  	enum mtk_dpi_out_bit_num bit_num;
>  	enum mtk_dpi_out_channel_swap channel_swap;
> +	struct pinctrl *pinctrl;
> +	struct pinctrl_state *pins_gpio;
> +	struct pinctrl_state *pins_dpi;
>  	int refcount;
>  	u32 pclk_sample;
>  };
> @@ -387,6 +392,9 @@ static void mtk_dpi_power_off(struct mtk_dpi *dpi)
>  	if (--dpi->refcount != 0)
>  		return;
>  
> +	if (dpi->pinctrl && dpi->pins_gpio)
> +		pinctrl_select_state(dpi->pinctrl, dpi->pins_gpio);
> +
>  	mtk_dpi_disable(dpi);
>  	clk_disable_unprepare(dpi->pixel_clk);
>  	clk_disable_unprepare(dpi->engine_clk);
> @@ -411,6 +419,9 @@ static int mtk_dpi_power_on(struct mtk_dpi *dpi)
>  		goto err_pixel;
>  	}
>  
> +	if (dpi->pinctrl && dpi->pins_dpi)
> +		pinctrl_select_state(dpi->pinctrl, dpi->pins_dpi);
> +
>  	mtk_dpi_enable(dpi);
>  	return 0;
>  
> @@ -716,8 +727,26 @@ static int mtk_dpi_probe(struct platform_device *pdev)
>  
>  	dpi->dev = dev;
>  	dpi->conf = (struct mtk_dpi_conf *)of_device_get_match_data(dev);
> -	dpi->pclk_sample = of_property_read_u32_index(dev->of_node,
> -						      "pclk-sample");
> +	of_property_read_u32_index(dev->of_node, "pclk-sample", 1,
> +				   &dpi->pclk_sample);

Why this exists in this patch?

> +
> +	dpi->pinctrl = devm_pinctrl_get(&pdev->dev);
> +	if (IS_ERR(dpi->pinctrl))
> +		dev_dbg(&pdev->dev, "Cannot find pinctrl!\n");

I think you should set dpi->pinctrl to NULL when error, and check
dpi->pinctrl before you use it, such as pinctrl_lookup_state().

Regards,
CK

> +
> +	dpi->pins_gpio = pinctrl_lookup_state(dpi->pinctrl, "gpiomode");
> +	if (IS_ERR(dpi->pins_gpio)) {
> +		dpi->pins_gpio = NULL;
> +		dev_dbg(&pdev->dev, "Cannot find pinctrl gpiomode!\n");
> +	}
> +	if (dpi->pinctrl && dpi->pins_gpio)
> +		pinctrl_select_state(dpi->pinctrl, dpi->pins_gpio);
> +
> +	dpi->pins_dpi = pinctrl_lookup_state(dpi->pinctrl, "dpimode");
> +	if (IS_ERR(dpi->pins_dpi)) {
> +		dpi->pins_dpi = NULL;
> +		dev_dbg(&pdev->dev, "Cannot find pinctrl dpimode!\n");
> +	}
>  
>  	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	dpi->regs = devm_ioremap_resource(dev, mem);