linux-parisc.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@lst.de>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Hellwig <hch@lst.de>, Guo Ren <guoren@kernel.org>,
	Michal Simek <monstr@monstr.eu>,
	Greentime Hu <green.hu@gmail.com>,
	Vincent Chen <deanbo422@gmail.com>, Guan Xuetao <gxt@pku.edu.cn>,
	the arch/x86 maintainers <x86@kernel.org>,
	alpha <linux-alpha@vger.kernel.org>,
	"open list:SYNOPSYS ARC ARCHITECTURE" 
	<linux-snps-arc@lists.infradead.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	"open list:QUALCOMM HEXAGON..." <linux-hexagon@vger.kernel.org>,
	linux-ia64@vger.kernel.org,
	linux-m68k <linux-m68k@lists.linux-m68k.org>,
	linux-mips@vger.kernel.org,
	"moderated list:NIOS2 ARCHITECTURE" 
	<nios2-dev@lists.rocketboards.org>,
	openrisc@lists.librecores.org,
	Parisc List <linux-parisc@vger.kernel.org>,
	linux-riscv@lists.infradead.org,
	linux-s390 <linux-s390@vger.kernel.org>,
	Linux-sh list <linux-sh@vger.kernel.org>,
	sparclinux <sparclinux@vger.kernel.org>,
	linux-xtensa@linux-xtensa.org,
	linux-mtd <linux-mtd@lists.infradead.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 10/21] asm-generic: ioremap_uc should behave the same with and without MMU
Date: Mon, 11 Nov 2019 11:15:31 +0100	[thread overview]
Message-ID: <20191111101531.GA12294@lst.de> (raw)
In-Reply-To: <CAK8P3a2o4R+E2hTrHrmNy7K1ki3_98aWE5a-fjkQ_NWW=xd_gQ@mail.gmail.com>

On Mon, Nov 11, 2019 at 11:09:05AM +0100, Arnd Bergmann wrote:
> Maybe we could move the definition into the atyfb driver itself?
> 
> As I understand it, the difference between ioremap()/ioremap_nocache()
> and ioremap_uc() only exists on pre-PAT x86-32 systems (i.e. 486, P5,
> Ppro, PII, K6, VIA C3), while on more modern systems (all non-x86,
> PentiumIII, Athlon, VIA C7)  those three are meant to be synonyms
> anyway.

That's not how I understood it.  Based on the code and the UC-
explanation ioremap_uc always overrides the MTRR, which can still
be present on more modern x86 systems.  In fact I remember a patch
floating around very recently adding another ioremap_uc caller in
some Atom platform device driver that works around buggy MTRR
tables.  Also this series actually adds a new override and a few
callers for ia64 platform code, which works very similar to x86
based on the comments in the code.  That being said I'm not sure
the callers in ia64 are really required, but it was the safest thing
to do as part of this cleanup.

  reply	other threads:[~2019-11-11 10:15 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-29  6:48 generic ioremap (and lots of cleanups) v3 Christoph Hellwig
2019-10-29  6:48 ` [PATCH 01/21] arm: remove ioremap_cached Christoph Hellwig
2019-11-11 10:33   ` Arnd Bergmann
2019-10-29  6:48 ` [PATCH 02/21] unicore32: " Christoph Hellwig
2019-10-29  6:48 ` [PATCH 03/21] ia64: rename ioremap_nocache to ioremap_uc Christoph Hellwig
2019-11-11 10:36   ` Arnd Bergmann
2019-10-29  6:48 ` [PATCH 04/21] hexagon: clean up ioremap Christoph Hellwig
2019-10-29  6:48 ` [PATCH 05/21] alpha: remove the unused __ioremap wrapper Christoph Hellwig
2019-10-29  6:48 ` [PATCH 06/21] nios2: remove __ioremap Christoph Hellwig
2019-10-29  6:48 ` [PATCH 07/21] parisc: " Christoph Hellwig
2019-11-05 14:29   ` Helge Deller
2019-10-29  6:48 ` [PATCH 08/21] x86: Clean up ioremap() Christoph Hellwig
2019-10-30 10:39   ` Thomas Gleixner
2019-10-29  6:48 ` [PATCH 09/21] xtensa: clean up ioremap Christoph Hellwig
2019-10-29  6:48 ` [PATCH 10/21] asm-generic: ioremap_uc should behave the same with and without MMU Christoph Hellwig
2019-11-06 17:56   ` Palmer Dabbelt
2019-11-11 10:09   ` Arnd Bergmann
2019-11-11 10:15     ` Christoph Hellwig [this message]
2019-11-11 10:27       ` Arnd Bergmann
2019-11-11 10:29         ` Christoph Hellwig
2019-11-11 19:33           ` Arnd Bergmann
2019-10-29  6:48 ` [PATCH 11/21] asm-generic: don't provide ioremap for CONFIG_MMU Christoph Hellwig
2019-11-06 18:11   ` Palmer Dabbelt
2019-11-06 18:16     ` Geert Uytterhoeven
2019-11-06 18:28       ` Christoph Hellwig
2019-11-11 10:31       ` Arnd Bergmann
2019-11-11 10:29   ` Arnd Bergmann
2019-10-29  6:48 ` [PATCH 12/21] arch: rely on asm-generic/io.h for default ioremap_* definitions Christoph Hellwig
2019-11-07 15:29   ` Palmer Dabbelt
2019-11-11 10:10   ` Arnd Bergmann
2019-10-29  6:48 ` [PATCH 13/21] m68k: rename __iounmap and mark it static Christoph Hellwig
2019-10-30  8:51   ` Geert Uytterhoeven
2019-10-29  6:48 ` [PATCH 14/21] hexagon: remove __iounmap Christoph Hellwig
2019-10-29  6:48 ` [PATCH 15/21] nios2: " Christoph Hellwig
2019-10-29  6:48 ` [PATCH 16/21] sh: " Christoph Hellwig
2019-10-29  6:48 ` [PATCH 17/21] lib: provide a simple generic ioremap implementation Christoph Hellwig
2019-11-07 15:29   ` Palmer Dabbelt
2019-11-11 10:10   ` Arnd Bergmann
2019-10-29  6:48 ` [PATCH 18/21] riscv: use the generic ioremap code Christoph Hellwig
2019-10-29  6:48 ` [PATCH 19/21] nds32: use generic ioremap Christoph Hellwig
2019-11-12  8:51   ` Greentime Hu
2019-10-29  6:48 ` [PATCH 20/21] csky: remove ioremap_cache Christoph Hellwig
2019-10-29  6:48 ` [PATCH 21/21] csky: use generic ioremap Christoph Hellwig
2019-11-05  1:31 ` generic ioremap (and lots of cleanups) v3 Christoph Hellwig
2019-11-07 20:47 ` generic-iomap tree for linux-next Christoph Hellwig
2019-11-08  2:20   ` Stephen Rothwell
2019-11-08  4:52     ` Stephen Rothwell
2019-11-08  5:14       ` Christoph Hellwig
  -- strict thread matches above, loose matches on Subject: below --
2019-10-17 17:45 generic ioremap (and lots of cleanups) v2 Christoph Hellwig
2019-10-17 17:45 ` [PATCH 10/21] asm-generic: ioremap_uc should behave the same with and without MMU Christoph Hellwig

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191111101531.GA12294@lst.de \
    --to=hch@lst.de \
    --cc=arnd@arndb.de \
    --cc=deanbo422@gmail.com \
    --cc=green.hu@gmail.com \
    --cc=guoren@kernel.org \
    --cc=gxt@pku.edu.cn \
    --cc=linux-alpha@vger.kernel.org \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-hexagon@vger.kernel.org \
    --cc=linux-ia64@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-m68k@lists.linux-m68k.org \
    --cc=linux-mips@vger.kernel.org \
    --cc=linux-mtd@lists.infradead.org \
    --cc=linux-parisc@vger.kernel.org \
    --cc=linux-riscv@lists.infradead.org \
    --cc=linux-s390@vger.kernel.org \
    --cc=linux-sh@vger.kernel.org \
    --cc=linux-snps-arc@lists.infradead.org \
    --cc=linux-xtensa@linux-xtensa.org \
    --cc=monstr@monstr.eu \
    --cc=nios2-dev@lists.rocketboards.org \
    --cc=openrisc@lists.librecores.org \
    --cc=sparclinux@vger.kernel.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).