linux-kernel - Re: [PATCH v2] pwm-backlight: fix the panel power sequence

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Message-ID: <1446798690.6203.3.camel@mtksdaap41>
Date:	Fri, 6 Nov 2015 16:31:30 +0800
From:	YH Huang <yh.huang@...iatek.com>
To:	Philipp Zabel <p.zabel@...gutronix.de>
CC:	<linux-pwm@...r.kernel.org>, <linux-fbdev@...r.kernel.org>,
	Jingoo Han <jingoohan1@...il.com>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	<linux-kernel@...r.kernel.org>,
	Thierry Reding <thierry.reding@...il.com>,
	<linux-mediatek@...ts.infradead.org>,
	Sascha Hauer <kernel@...gutronix.de>,
	Matthias Brugger <matthias.bgg@...il.com>,
	<yingjoe.chen@...iatek.com>, "Lee Jones" <lee.jones@...aro.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2] pwm-backlight: fix the panel power sequence

On Thu, 2015-11-05 at 10:40 +0100, Philipp Zabel wrote:
> > 
> > Based on this, could we disable it initially and update in the
> > backlight_update_status function?
> > 
> > Like this,
> > 
> > if (pb->enable_gpio) {
> > 	if (phandle &&
> > 	    gpiod_get_direction(pb->enable_gpio) == GPIOF_DIR_OUT &&
> > 	    gpiod_get_value(pb->enable_gpio) == 1)
> > 		gpiod_direction_output(pb->enable_gpio, 1);
> 
> The gpiod_direction_output call is a no-op, since the direction is
> already output and the value is already 1.
> Also, I propose to set initial blanking to FB_BLANK_POWERDOWN in this
> case, and wait for the panel driver to enable the backlight at the
> appropriate time.

Thanks your kindly reply.
Your patch looks good to me.

Regards,
YH Huang

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