From: Chris Wilson <chris@chris-wilson.co.uk>
To: Daniel Kurtz <djkurtz@chromium.org>
Cc: Daniel Vetter <daniel@ffwll.ch>,
Keith Packard <keithp@keithp.com>,
David Airlie <airlied@linux.ie>,
dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
Benson Leung <bleung@chromium.org>,
Yufeng Shen <miletus@chromium.org>
Subject: Re: [PATCH 13/13 v4] drm/i915/intel_i2c: reuse GMBUS2 value read in polling loop
Date: Wed, 28 Mar 2012 12:44:59 +0100 [thread overview]
Message-ID: <1332935113_126617@CP5-2952> (raw)
In-Reply-To: <CAGS+omBXmUfqGd9GYg4DhAmvn0Z1wkzGv8EZ3032_j0PikZn6g@mail.gmail.com>
On Wed, 28 Mar 2012 19:39:17 +0800, Daniel Kurtz <djkurtz@chromium.org> wrote:
> On Wed, Mar 28, 2012 at 3:02 AM, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> > Might as well shave this read as well.
>
> Do you know why POSTING_READ() was there in the first place?
> As far as I can tell, these are used to ensure memory barriers are
> inserted between a group of writes, and subsequent reads to memory
> mapped io registers.
> However, the normal I915_READ() and I915_WRITE() macros already call
> readl() / writel(), which already have an explicit mb().
> So, can we just get rid of all of them, or am I missing something?
They can go. They were there just as paranoia to make sure the writes
were flushed before any timing delays and across loops. Once the code
settled I never took the liberty of removing them.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
prev parent reply other threads:[~2012-03-28 11:44 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-27 18:36 [PATCH 00/13 v4] fix gmbus writes and related issues Daniel Kurtz
2012-03-27 18:36 ` [PATCH 01/13 v4] drm/i915/intel_i2c: refactor gmbus_xfer Daniel Kurtz
2012-03-27 19:09 ` Chris Wilson
2012-03-27 19:09 ` Chris Wilson
2012-03-27 18:36 ` [PATCH 02/13 v4] drm/i915/intel_i2c: cleanup error messages and comments Daniel Kurtz
2012-03-27 18:46 ` Chris Wilson
2012-03-27 18:46 ` Chris Wilson
2012-03-27 18:36 ` [PATCH 03/13 v4] drm/i915/intel_i2c: assign HDMI port D to pin pair 6 Daniel Kurtz
2012-03-27 18:36 ` [PATCH 04/13 v4] drm/i915/intel_i2c: use i2c pre/post_xfer functions to setup gpio xfers Daniel Kurtz
2012-03-27 18:57 ` Chris Wilson
2012-03-27 18:57 ` Chris Wilson
2012-03-27 18:36 ` [PATCH 05/13 v4] drm/i915/intel_i2c: refactor using intel_gmbus_get_adapter Daniel Kurtz
2012-03-27 18:36 ` [PATCH 06/13 v4] drm/i915/intel_i2c: gmbus disabled and reserved ports are invalid Daniel Kurtz
2012-03-27 18:36 ` [PATCH 07/13 v4] drm/i915/intel_i2c: allocate gmbus array as part of drm_i915_private Daniel Kurtz
2012-03-28 13:05 ` Daniel Vetter
2012-03-28 13:05 ` Daniel Vetter
2012-03-27 18:36 ` [PATCH 08/13 v4] drm/i915/intel_i2c: handle zero-length writes Daniel Kurtz
2012-03-27 19:14 ` Chris Wilson
2012-03-27 19:14 ` Chris Wilson
2012-03-28 11:32 ` Daniel Kurtz
2012-03-28 11:39 ` Chris Wilson
2012-03-27 18:36 ` [PATCH 09/13 v4] drm/i915/intel_i2c: use double-buffered writes Daniel Kurtz
2012-03-27 18:45 ` Chris Wilson
2012-03-27 18:45 ` Chris Wilson
2012-03-27 18:36 ` [PATCH 10/13 v4] drm/i915/intel_i2c: always wait for IDLE before clearing NAK Daniel Kurtz
2012-03-27 19:17 ` Chris Wilson
2012-03-27 19:17 ` Chris Wilson
2012-03-27 18:36 ` [PATCH 11/13 v4] drm/i915/intel_i2c: use WAIT cycle, not STOP Daniel Kurtz
2012-03-27 18:36 ` [PATCH 12/13 v4] drm/i915/intel_i2c: use INDEX cycles for i2c read transactions Daniel Kurtz
2012-03-28 13:21 ` Daniel Vetter
2012-03-27 18:36 ` [PATCH 13/13 v4] drm/i915/intel_i2c: reuse GMBUS2 value read in polling loop Daniel Kurtz
2012-03-27 19:02 ` Chris Wilson
2012-03-27 19:02 ` Chris Wilson
2012-03-28 11:39 ` Daniel Kurtz
2012-03-28 11:44 ` Chris Wilson [this message]
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