linux-kernel - Re: [PATCH 1/1] drm/panel: st7703: Pick different reset sequence

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Message-ID: <652ff2e8.050a0220.2e2de.4666@mx.google.com>
Date:   Wed, 18 Oct 2023 09:59:51 -0500
From:   Chris Morgan <macroalpha82@...il.com>
To:     Guido Günther <guido.gunther@...i.sm>
Cc:     Frank Oltmanns <frank@...manns.dev>,
        Ondrej Jirman <megous@...ous.com>,
        Purism Kernel Team <kernel@...i.sm>,
        Samuel Holland <samuel@...lland.org>,
        Sam Ravnborg <sam@...nborg.org>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:DRM PANEL DRIVERS" <dri-devel@...ts.freedesktop.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Ondrej Jirman <megi@....cz>, phone-devel@...r.kernel.org
Subject: Re: [PATCH 1/1] drm/panel: st7703: Pick different reset sequence

On Sun, Oct 15, 2023 at 02:49:20PM +0200, Guido Günther wrote:
> Hi,
> On Sat, Feb 11, 2023 at 06:17:48PM +0100, Frank Oltmanns wrote:
> > From: Ondrej Jirman <megi@....cz>
> > 
> > Switching to a different reset sequence, enabling IOVCC before enabling
> > VCC.
> > 
> > There also needs to be a delay after enabling the supplies and before
> > deasserting the reset. The datasheet specifies 1ms after the supplies
> > reach the required voltage. Use 10-20ms to also give the power supplies
> > some time to reach the required voltage, too.
> > 
> > This fixes intermittent panel initialization failures and screen
> > corruption during resume from sleep on panel xingbangda,xbd599 (e.g.
> > used in PinePhone).
> 
> Thanks, applied to drm-misc-next.
> Cheers,
>  -- Guido

Thank you. Probably too late, but this fixes problems I have with a
different ST7703 based panel.

Tested-by: Chris Morgan <macromorgan@...mail.com>

> 
> > 
> > Signed-off-by: Ondrej Jirman <megi@....cz>
> > Signed-off-by: Frank Oltmanns <frank@...manns.dev>
> > Reported-by: Samuel Holland <samuel@...lland.org>
> > ---
> >  drivers/gpu/drm/panel/panel-sitronix-st7703.c | 25 ++++++++++---------
> >  1 file changed, 13 insertions(+), 12 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/panel/panel-sitronix-st7703.c b/drivers/gpu/drm/panel/panel-sitronix-st7703.c
> > index 6747ca237ced..45695aa51f62 100644
> > --- a/drivers/gpu/drm/panel/panel-sitronix-st7703.c
> > +++ b/drivers/gpu/drm/panel/panel-sitronix-st7703.c
> > @@ -411,29 +411,30 @@ static int st7703_prepare(struct drm_panel *panel)
> >  		return 0;
> >  
> >  	dev_dbg(ctx->dev, "Resetting the panel\n");
> > -	ret = regulator_enable(ctx->vcc);
> > +	gpiod_set_value_cansleep(ctx->reset_gpio, 1);
> > +
> > +	ret = regulator_enable(ctx->iovcc);
> >  	if (ret < 0) {
> > -		dev_err(ctx->dev, "Failed to enable vcc supply: %d\n", ret);
> > +		dev_err(ctx->dev, "Failed to enable iovcc supply: %d\n", ret);
> >  		return ret;
> >  	}
> > -	ret = regulator_enable(ctx->iovcc);
> > +
> > +	ret = regulator_enable(ctx->vcc);
> >  	if (ret < 0) {
> > -		dev_err(ctx->dev, "Failed to enable iovcc supply: %d\n", ret);
> > -		goto disable_vcc;
> > +		dev_err(ctx->dev, "Failed to enable vcc supply: %d\n", ret);
> > +		regulator_disable(ctx->iovcc);
> > +		return ret;
> >  	}
> >  
> > -	gpiod_set_value_cansleep(ctx->reset_gpio, 1);
> > -	usleep_range(20, 40);
> > +	/* Give power supplies time to stabilize before deasserting reset. */
> > +	usleep_range(10000, 20000);
> > +
> >  	gpiod_set_value_cansleep(ctx->reset_gpio, 0);
> > -	msleep(20);
> > +	usleep_range(15000, 20000);
> >  
> >  	ctx->prepared = true;
> >  
> >  	return 0;
> > -
> > -disable_vcc:
> > -	regulator_disable(ctx->vcc);
> > -	return ret;
> >  }
> >  
> >  static const u32 mantix_bus_formats[] = {
> > -- 
> > 2.39.1
> >