linux-kernel - Re: [PATCH 13/62] gpio: gpio-f7188x: Use new GPIO_LINE

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Message-ID: <c7cc7d66a5d3e398bf5109f58260e9dca5a317df.camel@fi.rohmeurope.com>
Date:   Wed, 6 Nov 2019 06:44:59 +0000
From:   "Vaittinen, Matti" <Matti.Vaittinen@...rohmeurope.com>
To:     "simon.guinot@...uanux.org" <simon.guinot@...uanux.org>
CC:     "mazziesaccount@...il.com" <mazziesaccount@...il.com>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "bgolaszewski@...libre.com" <bgolaszewski@...libre.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linus.walleij@...aro.org" <linus.walleij@...aro.org>
Subject: Re: [PATCH 13/62] gpio: gpio-f7188x: Use new GPIO_LINE_DIRECTION

Morning Simon,

On Wed, 2019-11-06 at 06:34 +0100, Simon Guinot wrote:
> On Tue, Nov 05, 2019 at 12:16:03PM +0200, Matti Vaittinen wrote:
> > It's hard for occasional GPIO code reader/writer to know if values
> > 0/1
> > equal to IN or OUT. Use defined GPIO_LINE_DIRECTION_IN and
> > GPIO_LINE_DIRECTION_OUT to help them out.
> > 
> > Signed-off-by: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
> > ---
> >  drivers/gpio/gpio-f7188x.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpio/gpio-f7188x.c b/drivers/gpio/gpio-
> > f7188x.c
> > index fdc639f856f1..cadd02993539 100644
> > --- a/drivers/gpio/gpio-f7188x.c
> > +++ b/drivers/gpio/gpio-f7188x.c
> > @@ -250,7 +250,10 @@ static int f7188x_gpio_get_direction(struct
> > gpio_chip *chip, unsigned offset)
> >  
> >  	superio_exit(sio->addr);
> >  
> > -	return !(dir & 1 << offset);
> > +	if (dir & 1 << offset)
> > +		return GPIO_LINE_DIRECTION_OUT;
> > +
> > +	return GPIO_LINE_DIRECTION_IN
> 
> Hi Matti,
> 
> I am probably missing something but I can't find
> GPIO_LINE_DIRECTION_IN
> and GPIO_LINE_DIRECTION_OUT defined anywhere.

Sorry. I accidentally sent the patch 01/62 to limited audience - and
also messed up the message-ID from the series so threading messages is
probably not working :( I did resend the patch adding defines to all
reviewers yesterday - title should be "[RESEND PATCH 01/62] gpio: Add
definition for GPIO direction".

> Besides I am an occasional code reader/writer and I find the original
> code easy to understand.

Glad to hear that. When I read code:

return !(dir & 1 << offset);

It's impossible for me to tell if dir having bit at offset 'offset' set
means IN or OUT - I know the meaning of code, it checks this bit for
in/out - but which dir value is IN and which is OUT?

When this is written as:

	if (dir & 1 << offset)
		return GPIO_LINE_DIRECTION_OUT;

	return GPIO_LINE_DIRECTION_IN

it get's quite obvious even for me that having the matching bit set
means direction to be OUT.

Best Regards
	Matti Vaittinen