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Subject: Re: [RFC v2 10/39] gpio: add HAS_IOPORT dependencies
From:   Niklas Schnelle <schnelle@linux.ibm.com>
To:     Linus Walleij <linus.walleij@linaro.org>,
        William Breathitt Gray <william.gray@linaro.org>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-pci@vger.kernel.org, Arnd Bergmann <arnd@kernel.org>,
        Bartosz Golaszewski <brgl@bgdev.pl>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>
Date:   Mon, 02 May 2022 14:53:50 +0200
In-Reply-To: <CACRpkdaha37y-ZNSqYSbf=TvsJNcvbH1Y=N0JkVCewB-Lvf81Q@mail.gmail.com>
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         <f006229ae056d4cdcf57fc5722a695ad4c257182.camel@linux.ibm.com>
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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@linaro.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.