From: Christoph Hellwig <hch@lst.de>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Christoph Hellwig <hch@lst.de>, Arnd Bergmann <arnd@arndb.de>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
X86 ML <x86@kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
linux-ia64@vger.kernel.org, Tony Luck <tony.luck@intel.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
Souptick Joarder <jrdr.linux@gmail.com>,
dri-devel <dri-devel@lists.freedesktop.org>,
Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Luis Chamberlain <mcgrof@kernel.org>,
Tuowen Zhao <ztuowen@gmail.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Subject: Re: [PATCH] video: fbdev: atyfb: only use ioremap_uc() on i386 and ia64
Date: Tue, 12 Nov 2019 15:06:31 +0100 [thread overview]
Message-ID: <20191112140631.GA10922@lst.de> (raw)
In-Reply-To: <CAKMK7uEEz1n+zuTs29rbPHU74Dspaib=prpMge63L_-rUk_o4A@mail.gmail.com>
On Tue, Nov 12, 2019 at 02:04:16PM +0100, Daniel Vetter wrote:
> Wut ... Maybe I'm missing something, but from how we use mtrr in other
> gpu drivers it's a) either you use MTRR because that's all you got or
> b) you use pat. Mixing both sounds like a pretty bad idea, since if
> you need MTRR for performance (because you dont have PAT) then you
> can't fix the wc with the PAT-based ioremap_uc. And if you have PAT,
> then you don't really need an MTRR to get wc.
>
> So I'd revert this patch from Luis and ...
Sounds great to me..
> ... apply this one. Since the same reasoning should apply to anything
> that's running on any cpu with PAT.
Can you take a look at "mfd: intel-lpss: Use devm_ioremap_uc for MMIO"
in linux-next, which also looks rather fishy to me? Can't we use
the MTRR APIs to override the broken BIOS MTRR setup there as well?
With that we could kill ioremap_uc entirely.
next prev parent reply other threads:[~2019-11-12 14:06 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-11 19:22 [PATCH] video: fbdev: atyfb: only use ioremap_uc() on i386 and ia64 Arnd Bergmann
2019-11-12 10:55 ` Christoph Hellwig
2019-11-12 13:04 ` Daniel Vetter
2019-11-12 14:06 ` Christoph Hellwig [this message]
2019-11-12 14:26 ` Daniel Vetter
2019-11-12 22:24 ` Luis Chamberlain
2019-11-13 7:27 ` Christoph Hellwig
2019-11-13 7:38 ` Arnd Bergmann
2019-11-13 9:31 ` Andy Shevchenko
2019-11-13 18:45 ` Luis Chamberlain
2019-11-12 22:17 ` Luis Chamberlain
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=20191112140631.GA10922@lst.de \
--to=hch@lst.de \
--cc=andriy.shevchenko@linux.intel.com \
--cc=arnd@arndb.de \
--cc=b.zolnierkie@samsung.com \
--cc=bp@alien8.de \
--cc=daniel.vetter@ffwll.ch \
--cc=dri-devel@lists.freedesktop.org \
--cc=fenghua.yu@intel.com \
--cc=hpa@zytor.com \
--cc=jrdr.linux@gmail.com \
--cc=linux-fbdev@vger.kernel.org \
--cc=linux-ia64@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=maarten.lankhorst@linux.intel.com \
--cc=mcgrof@kernel.org \
--cc=mika.westerberg@linux.intel.com \
--cc=mingo@redhat.com \
--cc=tglx@linutronix.de \
--cc=tony.luck@intel.com \
--cc=x86@kernel.org \
--cc=ztuowen@gmail.com \
/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).