[PATCH 04/10] sata: hardreset: retry if phys link is down

Bartosz Golaszewski bgolaszewski at baylibre.com
Mon Jan 16 04:28:07 PST 2017

2017-01-16 0:10 GMT+01:00 Tejun Heo <tj at kernel.org>:
> Hello,
> On Fri, Jan 13, 2017 at 01:37:58PM +0100, Bartosz Golaszewski wrote:
>> The sata core driver already retries to resume the link because some
>> controllers ignore writes to the SControl register.
>> We have a use case with the da850 SATA controller where at PLL0
>> frequency of 456MHz (needed to properly service the LCD controller)
>> the chip becomes unstable and the hardreset operation is ignored the
>> first time 50% of times.
>> Retrying just the resume operation doesn't work - we need to issue
>> the phy/wake reset again to make it work.
>> If ata_phys_link_offline() returns true in sata_link_hardreset(),
>> retry a couple times before really giving up.
> I think it'd be better to implement the driver specific implementation
> rather than changing the behavior for everybody.
> Thanks.

For v2 I created a new ahci-locally exported function:
ahci_do_hardreset() that allows to retrieve the online state of the
link and used it in the da850-specific hardreset implementation.

Hope that'll be good.

Bartosz Golaszewski

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