linux-imx

[SCSI] aacraid: controller hangs if kernel uses non-default ASPM policy

Aacraid controller can hang on some nodes if kernel uses non-default
(powersave) ASPM policy.  Controller hangs shortly after successful load and
hardware detection. Scsi error handler detects this hang and tries to restart
hardware but it does not help.

Initially it was noticed on RHEL6-based openVZ kernel after backporting
aacraid driver from mainline (RHEL6 kernel with original driver works well)
http://bugzilla.openvz.org/show_bug.cgi?id=2043

This issue happens because default ASPM policy was changed in Red Hat
kernels. Therefore guys from Red Hat have noticed this problem long time ago:
on Fedora 12
 https://bugzilla.redhat.com/show_bug.cgi?id=540478
on Fedora 14
 https://bugzilla.redhat.com/show_bug.cgi?id=679385

In RHEL6 kernel this issue was fixed, ASPM was disabled in aacraid driver. In
kernel changelog I've found that seems it was done by Matthew Garrett: -
[scsi] aacraid: Disable ASPM by default (Matthew Garrett) [599735]

However seems this patch was not submitted to mainline. I've reproduced this
issue on vanilla 3.1.0 kernel booted with "pcie_aspm.policy=powersave" option,
So I believe it makes sense to do it now.

Signed-off-by:	Vasily Averin <vvs@sw.ru>
[mjg: Checking the Windows drivers indicates that they disable ASPM under all 
circumstances, so:]
Acked-by: Matthew Garrett <mjg@redhat.com>
Acked-by: Achim Leubner <Achim_Leubner@pmc-sierra.com>
Cc: stable@kernel.org
Signed-off-by: James Bottomley <JBottomley@Parallels.com>