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

Daniel Vetter daniel at ffwll.ch
Sun Mar 18 11:19:25 PDT 2012

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 at chromium.org>
> Signed-off-by: Daniel Kurtz <djkurtz at chromium.org>

This is already fixed in

commit 8a8ed1f5143b3df312e436ab15290e4a7ca6a559
Author: Yufeng Shen <miletus at chromium.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 


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

Thanks, Daniel
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48

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