Re: [PATCH v3] ata: increase retry count but shorten duration forCalxeda controller

From: Tejun Heo
Date: Sun Jun 02 2013 - 04:00:38 EST

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.

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