tree 15065ca2c11a849c583b2f6259722af90470b653
parent ce31072b43426e3bf45bc490e93504f5746cb9b5
author Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com> 1484125904 +0100
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1484853484 +0100

i2c: piix4: Avoid race conditions with IMC

commit 701dc207bf551d9fe6defa36e84a911e880398c3 upstream.

On AMD's SB800 and upwards, the SMBus is shared with the Integrated
Micro Controller (IMC).

The platform provides a hardware semaphore to avoid race conditions
among them. (Check page 288 of the SB800-Series Southbridges Register
Reference Guide http://support.amd.com/TechDocs/45482.pdf)

Without this patch, many access to the SMBus end with an invalid
transaction or even with the bus stalled.

Reported-by: Alexandre Desnoyers <alex@qtec.com>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>:
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>