From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Baoquan He <bhe@redhat.com>,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
linux-mm@kvack.org, arnd@arndb.de, mcgrof@kernel.org,
hch@infradead.org, linux-alpha@vger.kernel.org,
linux-hexagon@vger.kernel.org, linux-m68k@lists.linux-m68k.org,
linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-sh@vger.kernel.org,
sparclinux@vger.kernel.org
Subject: Re: [PATCH v3 2/2] arch/*/io.h: remove ioremap_uc in some architectures
Date: Sun, 5 Mar 2023 10:29:52 +0100 [thread overview]
Message-ID: <CAMuHMdXoM24uAZGcjBtscNMOSY_+4u08PEOR7gOfCH7jvCceDg@mail.gmail.com> (raw)
In-Reply-To: <87sfej1rie.fsf@mpe.ellerman.id.au>
Hi Michael,
On Sun, Mar 5, 2023 at 10:23 AM Michael Ellerman <mpe@ellerman.id.au> wrote:
> Baoquan He <bhe@redhat.com> writes:
> > ioremap_uc() is only meaningful on old x86-32 systems with the PAT
> > extension, and on ia64 with its slightly unconventional ioremap()
> > behavior, everywhere else this is the same as ioremap() anyway.
> >
> > Here, remove the ioremap_uc() definition in architecutures other
> > than x86 and ia64. These architectures all have asm-generic/io.h
> > included and will have the default ioremap_uc() definition which
> > returns NULL.
> >
> > Note: This changes the existing behaviour and could break code
> > calling ioremap_uc(). If any ARCH meets this breakage and really
> > needs a specific ioremap_uc() for its own usage, one ioremap_uc()
> > can be added in the ARCH.
>
> I see one use in:
>
> drivers/video/fbdev/aty/atyfb_base.c: par->ati_regbase = ioremap_uc(info->fix.mmio_start, 0x1000);
>
>
> Which isn't obviously x86/ia64 specific.
>
> I'm pretty sure some powermacs (powerpc) use that driver.
I originally wrote that driver for CHRP, so yes.
> Maybe that exact code path is only reachable on x86/ia64? But if so
> please explain why.
>
> Otherwise it looks like this series could break that driver on powerpc
> at least.
Indeed.
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
next prev parent reply other threads:[~2023-03-05 9:29 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20230303102817.212148-1-bhe@redhat.com>
2023-03-03 10:28 ` [PATCH v3 2/2] arch/*/io.h: remove ioremap_uc in some architectures Baoquan He
2023-03-05 9:23 ` Michael Ellerman
2023-03-05 9:29 ` Geert Uytterhoeven [this message]
2023-03-05 20:10 ` Arnd Bergmann
2023-03-07 0:58 ` Michael Ellerman
2023-03-07 1:30 ` Baoquan He
2023-03-07 7:17 ` Arnd Bergmann
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