From: Chris Wilson <chris@chris-wilson.co.uk>
To: Ben Widawsky <ben@bwidawsk.net>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 2/2] drm/i915: catch gtfifo errors on forcewake_put
Date: Sat, 04 Feb 2012 10:59:52 +0000 [thread overview]
Message-ID: <c55c5d$1s96ah@AZSMGA002.ch.intel.com> (raw)
In-Reply-To: <20120204021533.GA7186@snipes.kumite>
On Fri, 3 Feb 2012 18:15:33 -0800, Ben Widawsky <ben@bwidawsk.net> wrote:
> On Fri, Feb 03, 2012 at 11:10:09PM +0000, Chris Wilson wrote:
> > On Fri, 3 Feb 2012 14:31:41 -0800, Ben Widawsky <ben@bwidawsk.net> wrote:
> TBH, I don't really understand POSTING_READ that well. If it just
> requires that any read request made it through to the MCH (or whatever),
> then sure I can replace the POSTING_READ. Obviously though this is
> reading GTFIFODBG, and not FORCEWAKE, so you tell me.
The posting read is simply a PCI write/read ordering barrier. It can be
a read of any mmio address and before it is performed all previous writes
to mmio addresses must have been sent along the PCI and no subsequent write
is allowed to emitted ahead of the read. Hmm, so since the writes are in
fact weakly ordered (they are allowed to be emitted in any order so long
as they not reordered past a read), we would strictly need a barrier in
front of the write to disable forcewake if it were not for the buffering
performed by the chip of mmio writes under rc6.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
next prev parent reply other threads:[~2012-02-04 10:59 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-03 22:31 [PATCH 1/2] drm/i915: gtfifodbg in error state Ben Widawsky
2012-02-03 22:31 ` [PATCH 2/2] drm/i915: catch gtfifo errors on forcewake_put Ben Widawsky
2012-02-03 23:10 ` Chris Wilson
2012-02-04 2:15 ` Ben Widawsky
2012-02-04 10:59 ` Chris Wilson [this message]
2012-02-03 23:07 ` [PATCH 1/2] drm/i915: gtfifodbg in error state Chris Wilson
2012-02-04 12:54 ` Eugeni Dodonov
2012-02-04 19:48 ` [PATCH 2/2 v2] drm/i915: catch gtfifo errors on forcewake_put Ben Widawsky
2012-02-07 9:32 ` Daniel Vetter
2012-02-07 9:28 ` [PATCH 1/2] drm/i915: gtfifodbg in error state Daniel Vetter
2012-02-07 9:31 ` Chris Wilson
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='c55c5d$1s96ah@AZSMGA002.ch.intel.com' \
--to=chris@chris-wilson.co.uk \
--cc=ben@bwidawsk.net \
--cc=intel-gfx@lists.freedesktop.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.