linux-kernel - Re: [RFC v2 10/39] gpio: add HAS

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Message-ID: <1eeb5cdd40ccff8e27e55c230ff2cf04fe693fec.camel@linux.ibm.com>
Date:   Mon, 02 May 2022 14:53:50 +0200
From:   Niklas Schnelle <schnelle@...ux.ibm.com>
To:     Linus Walleij <linus.walleij@...aro.org>,
        William Breathitt Gray <william.gray@...aro.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-pci@...r.kernel.org, Arnd Bergmann <arnd@...nel.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>
Subject: Re: [RFC v2 10/39] gpio: add HAS_IOPORT dependencies

On Sun, 2022-05-01 at 23:55 +0200, Linus Walleij wrote:
> On Fri, Apr 29, 2022 at 5:37 PM William Breathitt Gray
> <william.gray@...aro.org> wrote:
> > On Fri, Apr 29, 2022 at 04:46:00PM +0200, Niklas Schnelle wrote:
> > > Good question. As far as I can see most (all?) of these have "select
> > > ISA_BUS_API" which is "def_bool ISA". Now "config ISA" seems to
> > > currently be repeated in architectures and doesn't have an explicit
> > > HAS_IOPORT dependency (it maybe should have one). But it does only make
> > > sense on architectures with HAS_IOPORT set.
> > 
> > There is such a thing as ISA DMA, but you'll still need to initialize
> > the device via the IO Port bus first, so perhaps setting HAS_IOPORT for
> > "config ISA" is the right thing to do: all ISA devices are expected to
> > communicate in some way via ioport.
> 
> Adding that dependency seems like the right solution to me.
> 
> Yours,
> Linus Walleij

One thing I forgot to mention, config HAS_IOPORT does have a "def_bool
ISA" but yes I agree an explicit "depends on HAS_IOPORT" for ISA seems
more logical. I also haven't found issues trying this out locally so
far.