From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH] libata-pmp: clear hob for pmp register accesses Date: Fri, 22 Feb 2008 10:40:41 +0900 Message-ID: <47BE2819.90601@gmail.com> References: <4730E312.3090900@navy.mil> <4737C16E.3070607@gmail.com> <4738827D.9060405@pobox.com> <4738F935.1000708@gmail.com> <47BC798F.6070900@pobox.com> <47BCF28F.5080702@gmail.com> <47BD93BC.3080301@pobox.com> <47BDE489.6070701@rtr.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from nf-out-0910.google.com ([64.233.182.191]:42856 "EHLO nf-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760140AbYBVBku (ORCPT ); Thu, 21 Feb 2008 20:40:50 -0500 Received: by nf-out-0910.google.com with SMTP id g13so163500nfb.21 for ; Thu, 21 Feb 2008 17:40:48 -0800 (PST) In-Reply-To: <47BDE489.6070701@rtr.ca> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Mark Lord Cc: Jeff Garzik , IDE/ATA development list , Saeed Bishara Mark Lord wrote: > Mark Lord wrote: >> Tejun Heo wrote: >>> Hello, Mark. >>> >>> 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. > .. > > Saeed has confirmed this behaviour 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 > Acked-by: Mark Lord Acked-by: Tejun Heo I think this is correct w/ or w/o the mv problem. -- tejun