Re: [PATCH 1/1] AHCI: disabled FBS prior to issuing software reset

From: Tejun Heo <tj@kernel.org>
To: Xiangliang Yu <yxlraid@gmail.com>
Cc: linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] AHCI: disabled FBS prior to issuing software reset
Date: Sat, 28 Sep 2013 07:49:50 -0400	[thread overview]
Message-ID: <20130928114950.GA2620@htj.dyndns.org> (raw)
In-Reply-To: <1380366816-16221-1-git-send-email-yxlraid@gmail.com>

Hello,

On Sat, Sep 28, 2013 at 07:13:36PM +0800, Xiangliang Yu wrote:
> If device is attached to port multiplier, the detection process
> look like this:
> 	ahci_hardreset(link, class, deadline)
> 	if (class == ATA_DEV_PMP) {
> 		sata_pmp_attach(dev)    /* will enable FBS */
> 		sata_pmp_init_links(ap, nr_ports);
> 		ata_for_each_link(link, ap, EDGE) {
> 			sata_std_hardreset(link, class, deadline);
> 			if (link_is_online)
> 				ahci_softreset(link, class, deadline);
> 		}
> 	}
> But, according to chapter 9.3.9 in AHCI spec: Prior to issuing software reset,
> software shall clear PxCMD.ST to '0' and then clear PxFBS.EN to '0'.

How was this tested?  Do you observe any behavior difference?  At this
point, we are not using SRST on PMP ports anyway, so I can't see how
this would make any difference.

Thanks.

-- 
tejun