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[209.85.128.182]) by smtp.gmail.com with ESMTPSA id 82-20020a370755000000b007423a896659sm5312677qkh.86.2023.03.05.01.30.04 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 05 Mar 2023 01:30:04 -0800 (PST) Received: by mail-yw1-f182.google.com with SMTP id 00721157ae682-53852143afcso128738367b3.3 for ; Sun, 05 Mar 2023 01:30:04 -0800 (PST) X-Received: by 2002:a81:af0c:0:b0:52f:1c23:ef1 with SMTP id n12-20020a81af0c000000b0052f1c230ef1mr4669025ywh.5.1678008604127; Sun, 05 Mar 2023 01:30:04 -0800 (PST) MIME-Version: 1.0 References: <20230303102817.212148-1-bhe@redhat.com> <20230303102817.212148-3-bhe@redhat.com> <87sfej1rie.fsf@mpe.ellerman.id.au> In-Reply-To: <87sfej1rie.fsf@mpe.ellerman.id.au> From: Geert Uytterhoeven Date: Sun, 5 Mar 2023 10:29:52 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v3 2/2] arch/*/io.h: remove ioremap_uc in some architectures To: Michael Ellerman Cc: Baoquan He , 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 80071C0004 X-Stat-Signature: c7nnjm7kcitxeweu83ubqoh566hmooy6 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1678008606-305363 X-HE-Meta: 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 PZylgQ9H 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi Michael, On Sun, Mar 5, 2023 at 10:23=E2=80=AFAM Michael Ellerman wrote: > Baoquan He 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 =3D 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 --=20 Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k= .org In personal conversations with technical people, I call myself a hacker. Bu= t when I'm talking to journalists I just say "programmer" or something like t= hat. -- Linus Torvalds