From: Mark Lord <liml@rtr.ca>
Date: Thu, 21 Feb 2008 20:52:25 +0000 (-0500)
Subject: libata-pmp: clear hob for pmp register accesses
X-Git-Tag: v2.6.25-rc3~8^2~3
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=39f25e70ca37b8a719e8274e6f3ec2ce2ea8df04;p=pandora-kernel.git

libata-pmp: clear hob for pmp register accesses

>> Mark Lord wrote:
>>> Tejun, I've added PMP to sata_mv, and am now trying to get it
>>> to work with a Marvell PM attached.
>>>
>>> And the behaviour I see is very bizarre.
>>>
>>> After hard+soft resets, the PM signature is found,
>>> and libata interrogates the PM registers.
>>>
>>> It successfully reads register 0, and then register 1.
>>> But all subsequent registers read out (incorrectly) as zeros.
...

This behavior has been confirmed by Marvell with a SATA analyzer.
The Marvell port-multiplier apparently likes to see clean HOB
information when accessing PMP registers.

Since sata_mv uses PIO shadow register access, this doesn't happen
automatically, as it might in a more purely FIS-based driver (eg. ahci).

One way to fix this is to flag these commands with ATA_TFLAG_LBA48,
forcing libata to write out the HOB fields with known (zero) values.

Signed-off-by: Saeed Bishara <saeed@marvell.com>
Acked-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
---

Reading git-diff-tree failed