Re: [PATCH 4.2 108/110] pinctrl: baytrail: Serialize all register access

From: Ben Hutchings
Date: Sun Nov 08 2015 - 04:38:58 EST

On Fri, 2015-11-06 at 11:19 -0800, Greg Kroah-Hartman wrote:
> 4.2-stable review patch.ÂÂIf anyone has any objections, please let me know.
> ------------------
> From: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> commit 39ce8150a079e3ae6ed9abf26d7918a558ef7c19 upstream.
> There is a hardware issue in Intel Baytrail where concurrent GPIO register
> access might result reads of 0xffffffff and writes might get dropped
> completely.
> Prevent this from happening by taking the serializing lock in all places
> where it is possible that more than one thread might be accessing the
> hardware concurrently.

While I have no objection to this, I think a complete fix requires
adding mmiowb() before each spin_unlock.


Ben Hutchings
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