linux-kernel - Re: [PATCH v5 30/44] rtc: add HAS

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Date:   Tue, 4 Jul 2023 14:46:23 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Niklas Schnelle <schnelle@...ux.ibm.com>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Alan Stern <stern@...land.harvard.edu>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        linux-kernel@...r.kernel.org,
        Linux-Arch <linux-arch@...r.kernel.org>,
        linux-pci@...r.kernel.org, Arnd Bergmann <arnd@...nel.org>,
        linux-rtc@...r.kernel.org, "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH v5 30/44] rtc: add HAS_IOPORT dependencies

Hi Arnd,

On Tue, Jul 4, 2023 at 1:25 PM Arnd Bergmann <arnd@...db.de> wrote:
> On Tue, Jul 4, 2023, at 10:06, Geert Uytterhoeven wrote:
> > On Mon, May 22, 2023 at 12:51 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, which is now commit 8bb12adb214b2d7c ("rtc:
> > add HAS_IOPORT dependencies") upstream.
> >
> >> --- a/drivers/rtc/Kconfig
> >> +++ b/drivers/rtc/Kconfig
> >> @@ -1193,7 +1195,7 @@ config RTC_DRV_MSM6242
> >>
> >>  config RTC_DRV_BQ4802
> >>         tristate "TI BQ4802"
> >> -       depends on HAS_IOMEM
> >> +       depends on HAS_IOMEM && HAS_IOPORT
> >>         help
> >>           If you say Y here you will get support for the TI
> >>           BQ4802 RTC chip.
> >
> > This driver can use either iomem or ioport.
> > By adding a dependency on HAS_IOPORT, it can no longer be used
> > on platforms that provide HAS_IOMEM only.
>
> You are correct, we could allow building this driver even
> without IOPORT and make it use ioport_map() or an #ifdef.
>
> > Probably the driver should be refactored to make it use only
> > the accessors that are available.
>
> Since the driver itself has no DT support, it looks like the
> only way it can be used is from the sparc64/ultra45 wrapper,
> but that architecture always provides CONFIG_IOPORT, so I
> don't think it makes any difference in the end. We can change
> this again if another user comes up.

Correct, I made the same reasoning after sending my previous email...

> It might be good to know whether the machine uses a memory or
> I/O resource in its device tree.

Indeed.

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