Message-ID: <b21410ee32857b4913e4ba4595f9e8da299c501f.camel@linux.ibm.com>
Subject: Re: [RFC 12/32] iio: adc: Kconfig: add HAS_IOPORT dependencies
From:   Niklas Schnelle <schnelle@linux.ibm.com>
To:     Geert Uytterhoeven <geert@linux-m68k.org>
Cc:     Arnd Bergmann <arnd@kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        John Garry <john.garry@huawei.com>,
        Nick Hu <nickhu@andestech.com>,
        Greentime Hu <green.hu@gmail.com>,
        Vincent Chen <deanbo422@gmail.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>, Guo Ren <guoren@kernel.org>,
        Jonathan Cameron <jic23@kernel.org>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux-Arch <linux-arch@vger.kernel.org>,
        linux-pci <linux-pci@vger.kernel.org>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        linux-csky@vger.kernel.org, linux-iio@vger.kernel.org
Date:   Tue, 28 Dec 2021 13:50:20 +0100
In-Reply-To: <CAMuHMdXDL6XXfohzJFTTV6tR=gg=bcCQq935eKUbNaNLHp9xiw@mail.gmail.com>
References: <20211227164317.4146918-1-schnelle@linux.ibm.com>
         <20211227164317.4146918-13-schnelle@linux.ibm.com>
         <CAMuHMdXDL6XXfohzJFTTV6tR=gg=bcCQq935eKUbNaNLHp9xiw@mail.gmail.com>
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On Tue, 2021-12-28 at 11:32 +0100, Geert Uytterhoeven wrote:
> Hi Niklas,
> 
> On Mon, Dec 27, 2021 at 5:53 PM Niklas Schnelle <schnelle@linux.ibm.com> wrote:
> > In a future patch HAS_IOPORT=n will result in inb()/outb() and friends
> > not being declared. We thus need to add HAS_IOPORT as dependency for
> > those drivers using them.
> > 
> > Co-developed-by: Arnd Bergmann <arnd@kernel.org>
> > Signed-off-by: Arnd Bergmann <arnd@kernel.org>
> > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
> 
> Thanks for your patch!
> 
> > --- a/drivers/iio/adc/Kconfig
> > +++ b/drivers/iio/adc/Kconfig
> > @@ -119,7 +119,7 @@ config AD7606
> > 
> >  config AD7606_IFACE_PARALLEL
> >         tristate "Analog Devices AD7606 ADC driver with parallel interface support"
> > -       depends on HAS_IOMEM
> > +       depends on HAS_IOPORT
> 
> While this driver uses ins[bw](), this seems unrelated to legacy
> I/O space, as the driver maps a MMIO region.  Probably different
> accessors should be used instead.

You're right on first glance it looks like a misuse of the ins[bw]()
accessors. I do wonder how that even works, if PCI_IOBASE is 0 it would
result in readsw()/readsb() with presumably the correct address but no
idea how this interacts witth x86's special I/O instructions.

> 
> Note that this driver has no in-tree users. Same for the SPI variant,
> but at least that one has modern json-schema DT bindings ;-)

Can't find any mention in the MAINTAINERS file either.

> 
> >         select AD7606
> >         help
> >           Say yes here to build parallel interface support for Analog Devices:
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds