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Message-ID: <20130602080010.GB8286@mtj.dyndns.org>
Date: Sun, 2 Jun 2013 01:00:10 -0700
From: Tejun Heo <tj@...nel.org>
To: Mark Langsdorf <mark.langsdorf@...xeda.com>
Cc: timur@...i.org, linux-kernel@...r.kernel.org,
linux-ide@...r.kernel.org, clemens@...isch.de,
sergei.shtylyov@...entembedded.com
Subject: Re: [PATCH v3] ata: increase retry count but shorten duration for
Calxeda controller
On Fri, May 31, 2013 at 10:27:26AM -0500, Mark Langsdorf wrote:
> The Calxeda SATA phy intermittently fails to bring up a link with Gen3
> Retrying the phy hard reset can work around the issue, but the drive
> may fail again. In less than 150 out of 15000 test runs, it took more
> than 10 tries for the link to be established (but never more than 35).
> Triple the maximum observed retry count to provide plenty of margin for
> rare events and to guarantee that the link is established.
>
> Also, the default 2 second time-out on a failed drive is too long in
> this situation. The uboot implementation of the same driver function
> uses a much shorter time-out period and never experiences a time out
> issue. Shorten the Linux time-out value for this driver to 500 ms and
> keep the other timing constants the same as the stock AHCI driver. This
> change was also tested 15000 times on 24 drives and none of them
> experienced a time out.
For the third time, explain the above in the comment; otherwise, it's
not going in.
--
tejun
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