linux-kernel - Re: [PATCH] drm: mediatek: Modify dpi power on/off sequence.

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Date:   Wed, 9 Nov 2022 02:27:13 +0000
From:   Xinlei Lee (李昕磊) 
        <Xinlei.Lee@...iatek.com>
To:     CK Hu (胡俊光) <ck.hu@...iatek.com>,
        "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "daniel@...ll.ch" <daniel@...ll.ch>,
        "chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>,
        "airlied@...ux.ie" <airlied@...ux.ie>,
        Jitao Shi (石记涛) <jitao.shi@...iatek.com>
CC:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Project_Global_Chrome_Upstream_Group 
        <Project_Global_Chrome_Upstream_Group@...iatek.com>
Subject: Re: [PATCH] drm: mediatek: Modify dpi power on/off sequence.

On Tue, 2022-11-08 at 07:44 +0000, CK Hu (胡俊光) wrote:
> Hi, Xinlei:
> 
> On Wed, 2022-10-12 at 15:48 +0800, xinlei.lee wrote:
> > On Mon, 2022-09-05 at 21:53 +0800, xinlei.lee@...iatek.com wrote:
> > > From: Xinlei Lee <xinlei.lee@...iatek.com>
> > > 
> > > Modify dpi power on/off sequence so that the first gpio operation
> > > will take effect.
> > > 
> > > Fixes: 6bd4763fd532 ("drm/mediatek: set dpi pin mode to gpio low
> > > to
> > > avoid leakage
> > > current")
> > > 
> > > Signed-off-by: Xinlei Lee <xinlei.lee@...iatek.com>
> > > 
> > > ---
> > > Base on the branch of Linux-next/master.
> > > Because dpi power_on/off is protected by dpi->refcount, the first
> > > time
> > > it cannot be powered on and off successfully, it will cause
> > > leakage.
> > > ---
> > > ---
> > >  drivers/gpu/drm/mediatek/mtk_dpi.c | 12 ++++++------
> > >  1 file changed, 6 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c
> > > b/drivers/gpu/drm/mediatek/mtk_dpi.c
> > > index 630a4e301ef6..2ce1a39ce3bf 100644
> > > --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> > > +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> > > @@ -462,9 +462,6 @@ 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);
> > > @@ -489,9 +486,6 @@ 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);
> > > -
> > >  	return 0;
> > >  
> > >  err_pixel:
> > > @@ -721,6 +715,9 @@ static void mtk_dpi_bridge_disable(struct
> > > drm_bridge *bridge)
> > >  {
> > >  	struct mtk_dpi *dpi = bridge_to_dpi(bridge);
> > >  
> > > +	if (dpi->pinctrl && dpi->pins_gpio)
> > > +		pinctrl_select_state(dpi->pinctrl, dpi->pins_gpio);
> 
> I think this should be placed after mtk_dpi_power_off().
> 
> > > +
> > >  	mtk_dpi_power_off(dpi);
> > >  }
> > >  
> > > @@ -728,6 +725,9 @@ static void mtk_dpi_bridge_enable(struct
> > > drm_bridge *bridge)
> > >  {
> > >  	struct mtk_dpi *dpi = bridge_to_dpi(bridge);
> > >  
> > > +	if (dpi->pinctrl && dpi->pins_dpi)
> > > +		pinctrl_select_state(dpi->pinctrl, dpi->pins_dpi);
> > > +
> > >  	mtk_dpi_power_on(dpi);
> > >  	mtk_dpi_set_display_mode(dpi, &dpi->mode);
> > >  	mtk_dpi_enable(dpi);
> > 
> > Hi CK,
> > 
> > Gentle ping for this patch, if there is anything I need to modify,
> > please kindly let me know.
> > 
> > Best Regards!
> > xinlei
> > 

Hi CK:

Yes, this pacth is mainly to remove the control of the pin from 
dpi_power_on/off, because dpi_power_on/off is protected by refcount.

I will modify the position of the pull-down gpio in the next version.

Best Regards!
xinlei