linux-kernel - Re: [PATCH 2/3] gpio: 104-idio-16: Utilize the idio-16 GPIO library

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Date:   Tue, 13 Sep 2022 12:25:54 -0400
From:   William Breathitt Gray <wbg@...nel.org>
To:     Andy Shevchenko <andriy.shevchenko@...el.com>
Cc:     William Breathitt Gray <william.gray@...aro.org>, brgl@...ev.pl,
        linus.walleij@...aro.org, linux-kernel@...r.kernel.org,
        linux-gpio@...r.kernel.org
Subject: Re: [PATCH 2/3] gpio: 104-idio-16: Utilize the idio-16 GPIO library

On Tue, Sep 13, 2022 at 07:19:03PM +0300, Andy Shevchenko wrote:
> On Sun, Sep 11, 2022 at 04:34:39PM -0400, William Breathitt Gray wrote:
> > The ACCES 104-IDIO-16 device is part of the ACCES IDIO-16 family, so the
> > idio-16 GPIO library module is selected and utilized to consolidate
> > code.
> 
> > +	/* Reading output signals is not supported */
> > +	if (offset < IDIO_16_NOUT)
> >  		return -EINVAL;
> 
> I see it's in the original code, but isn't it possible to cache and return
> cached value in such cases?
> 
> -- 
> With Best Regards,
> Andy Shevchenko

I think you're right, we're already caching the outputs for the sake of
the signal set calls, so we can just return those respective output
values for the signal get calls. It should also save us some cycles by
avoiding the read8() calls for the outputs in the PCI-IDIO-16 case.

William Breathitt Gray

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