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    SubjectRe: [PATCH 4.2 108/110] pinctrl: baytrail: Serialize all register access
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    On Fri, 2015-11-06 at 11:19 -0800, Greg Kroah-Hartman wrote:
    > 4.2-stable review patch.  If anyone has any objections, please let me know.
    >
    > ------------------
    >
    > From: Mika Westerberg <mika.westerberg@linux.intel.com>
    >
    > 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.

    --
    Ben Hutchings
    73.46% of all statistics are made up.[unhandled content-type:application/pgp-signature]
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