linux-kernel - Re: [PATCH 5/9] drm/i915/intel_i2c: add locking around i2c algorithm accesses

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Message-ID: <20120318181925.GG4286@phenom.ffwll.local>
Date:	Sun, 18 Mar 2012 19:19:25 +0100
From:	Daniel Vetter <daniel@...ll.ch>
To:	Daniel Kurtz <djkurtz@...omium.org>
Cc:	Keith Packard <keithp@...thp.com>, David Airlie <airlied@...ux.ie>,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	Yufeng Shen <miletus@...omium.org>,
	Benson Leung <bleung@...omium.org>,
	Sameer Nanda <snanda@...omium.org>
Subject: Re: [PATCH 5/9] drm/i915/intel_i2c: add locking around i2c algorithm
 accesses

On Wed, Mar 07, 2012 at 07:50:46PM +0800, Daniel Kurtz wrote:
> The i915 has multiple i2c adapters.  However, they all share a single
> single set of i2c control registers (algorithm).  Thus, different threads
> trying to access different adapters could interfere with each other.
> 
> Note: different threads trying to access the same channel is already
> handled in the i2c-core using the i2c adapter lock.
> 
> This patch adds a mutex to serialize access to the gmbus_xfer routine.
> Note: the same mutex serializes both bit banged and native xfers.
> 
> Signed-off-by: Yufeng Shen <miletus@...omium.org>
> Signed-off-by: Daniel Kurtz <djkurtz@...omium.org>

This is already fixed in

commit 8a8ed1f5143b3df312e436ab15290e4a7ca6a559
Author: Yufeng Shen <miletus@...omium.org>
Date:   Mon Feb 13 17:36:54 2012 -0500

    drm/i915: Fix race condition in accessing GMBUS

There are also a few gmbus changes already queued up in my -next tree at 

http://cgit.freedesktop.org/~danvet/drm-intel/log/?h=drm-intel-next-queued

Please rebase your patch series on top of that (with Chris' suggestion
incorporated).

Thanks, Daniel
-- 
Daniel Vetter
Mail: daniel@...ll.ch
Mobile: +41 (0)79 365 57 48
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