linux-kernel - Re: [PATCH 1/2] backlight: hx8357: switch to using gpiod API

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Message-ID: <Y+HQfDtiqUso7e9k@google.com>
Date:   Mon, 6 Feb 2023 20:15:56 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Daniel Thompson <daniel.thompson@...aro.org>
Cc:     Lee Jones <lee@...nel.org>, Jingoo Han <jingoohan1@...il.com>,
        Helge Deller <deller@....de>, dri-devel@...ts.freedesktop.org,
        linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] backlight: hx8357: switch to using gpiod API

On Mon, Feb 06, 2023 at 11:35:32AM +0000, Daniel Thompson wrote:
> On Tue, Jan 31, 2023 at 02:57:06PM -0800, Dmitry Torokhov wrote:
> > Switch the driver from legacy gpio API that is deprecated to the newer
> > gpiod API that respects line polarities described in ACPI/DT.
> >
> > This makes driver use standard property name for the reset gpio
> > ("reset-gpios" vs "gpios-reset"), however there is a quirk in gpiolib
> > to also recognize the legacy name and keep compatibility with older
> > DTSes.
> >
> > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
> > ---
> >
> > All preparation gpiolib work to handle legacy names and polarity quirks
> > has landed in mainline...
> >
> >  drivers/video/backlight/hx8357.c | 82 ++++++++++++++------------------
> >  1 file changed, 37 insertions(+), 45 deletions(-)
> >
> > diff --git a/drivers/video/backlight/hx8357.c b/drivers/video/backlight/hx8357.c
> > index 9b50bc96e00f..a93e14adb846 100644
> > --- a/drivers/video/backlight/hx8357.c
> > +++ b/drivers/video/backlight/hx8357.c
> > [snip]
> > -	if (of_find_property(spi->dev.of_node, "im-gpios", NULL)) {
> > -		lcd->use_im_pins = 1;
> > -
> > -		for (i = 0; i < HX8357_NUM_IM_PINS; i++) {
> > -			lcd->im_pins[i] = of_get_named_gpio(spi->dev.of_node,
> > -							    "im-gpios", i);
> > -			if (lcd->im_pins[i] == -EPROBE_DEFER) {
> > -				dev_info(&spi->dev, "GPIO requested is not here yet, deferring the probe\n");
> > -				return -EPROBE_DEFER;
> > -			}
> > -			if (!gpio_is_valid(lcd->im_pins[i])) {
> > -				dev_err(&spi->dev, "Missing dt property: im-gpios\n");
> > -				return -EINVAL;
> > +	gpiod_set_consumer_name(lcd->reset, "hx8357-reset");
> > +
> > +	for (i = 0; i < HX8357_NUM_IM_PINS; i++) {
> > +		lcd->im_pins[i] = devm_gpiod_get_index(&spi->dev,
> > +						       "im", i, GPIOD_OUT_LOW);
> > +		ret = PTR_ERR_OR_ZERO(lcd->im_pins[i]);
> > +		if (ret) {
> > +			if (ret == -ENOENT) {
> > +				if (i == 0)
> > +					break;
> > +				dev_err(&spi->dev, "Missing im gpios[%d]\n", i);
> > +				ret = -EINVAL;
> > +			} if (ret == -EPROBE_DEFER) {

I see I miss "else" here...

> > +				dev_info(&spi->dev, "im gpio[%d] is not here yet, deferring the probe\n",
> > +					 i);
> > +			} else {
> > +				dev_err(&spi->dev, "failed to request im gpio[%d]: %d\n",
> > +					i, ret);
> >  			}
> 
> These last two clauses should be updated to return dev_err_probe(...)
> instead.
> 
> With that change:
> Reviewed-by: Daniel Thompson <daniel.thompson@...aro.org>

So you want to actually suppress the deferral message unless debug
printks are enabled? So you want this to read:


		if (ret) {
			if (ret == -ENOENT) {
				if (i == 0)
					break;

				dev_err(&spi->dev, "Missing im gpios[%d]\n", i);
				return -EINVAL;
			}

			return dev_err_probe(&spi->dev, ret,
					     "failed to request im gpio[%d]\n", i);
		}


Did I get it right?

Thanks.

-- 
Dmitry