linux-kernel - Re: [RFC 10/32] i2c: Kconfig: add HAS

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Date:   Tue, 28 Dec 2021 13:13:17 +0100
From:   Niklas Schnelle <schnelle@...ux.ibm.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Arnd Bergmann <arnd@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        John Garry <john.garry@...wei.com>,
        Nick Hu <nickhu@...estech.com>,
        Greentime Hu <green.hu@...il.com>,
        Vincent Chen <deanbo422@...il.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>, Guo Ren <guoren@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux-Arch <linux-arch@...r.kernel.org>,
        linux-pci <linux-pci@...r.kernel.org>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        linux-csky@...r.kernel.org, Linux I2C <linux-i2c@...r.kernel.org>
Subject: Re: [RFC 10/32] i2c: Kconfig: add HAS_IOPORT dependencies

On Tue, 2021-12-28 at 11:21 +0100, Geert Uytterhoeven wrote:
> Hi Niklas,
> 
> On Mon, Dec 27, 2021 at 5:49 PM Niklas Schnelle <schnelle@...ux.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@...nel.org>
> > Signed-off-by: Arnd Bergmann <arnd@...nel.org>
> > Signed-off-by: Niklas Schnelle <schnelle@...ux.ibm.com>
> 
> Thanks for your patch!
> 
> > --- a/drivers/i2c/busses/Kconfig
> > +++ b/drivers/i2c/busses/Kconfig
> > @@ -828,6 +828,7 @@ config I2C_NPCM7XX
> > 
> >  config I2C_OCORES
> >         tristate "OpenCores I2C Controller"
> > +       depends on HAS_IOPORT
> 
> While drivers/i2c/busses/i2c-ocores.c does use {in,out}(), I doubt this
> is used to access legacy I/O space.

Hmm, it does use i2c->iobase for inb()/outb() but i2c->base for
ioreadXY()/iowriteXY(). And as it gets i2c->iobase from
platform_get_resource(pdev, IORESOURCE_IO, 0) I'd think that is an I/O
resource/space. It does look like some kind of fallback path though,
the IORESOURCE_IO is only looked at if accessing an IORESOURCE_MEM
fails so maybe that should instead be ifdeffed.

> 
> >         help
> >           If you say yes to this option, support will be included for the
> >           OpenCores I2C controller. For details see
> > @@ -1227,6 +1228,7 @@ config I2C_CP2615
> >  config I2C_PARPORT
> >         tristate "Parallel port adapter"
> >         depends on PARPORT
> > +       depends on HAS_IOPORT
> 
> Same as PRINTER: shouldn't this work with all parport drivers?

Agree, will drop.

> 
> >         select I2C_ALGOBIT
> >         select I2C_SMBUS
> >         help
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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