Re: [PATCH] ata: libata-sata: retry hardreset when device detected but PHY not established

[Niklas Cassel <cassel@kernel.org>]

On Wed, Apr 29, 2026 at 03:01:48PM +0800, yangxingui wrote:
> > > > > > This is preceeded by a call to sata_link_resume(), which calls
> > > > > > sata_link_debounce() and that function makes sure that DET is stable. So if
> > > > > > after that DET still shows that their is no PHY, there is likely a big problem
> > > > > > with it and it is super slow to be established.

I agree with Damien, sata_link_debounce() is supposed to make sure that
DET is stable.


sata_link_debounce() will not explicitly wait for SStatus.DET to turn 0x3.

If value is stable, and SStatus.DET == 1, and time is before "deadline",
sata_link_debounce() will continue looping.

Else, if value is stable, and has been stable for "duration" amount of time,
it will return.

Since your print shows that SStatus == 1, that most likely means that the
deadline expired in sata_link_debounce().

I suggest that you try to increase the deadline, perhaps start off by simply
multiplying it by some factor in sata_link_debounce().


It would also be helpful if your commit message explained why returning
-EAGAIN makes a difference, because from what I can see, if the deadline
expires, sata_link_debounce() returns 0, which should cause sata_link_resume()
to return 0, which should cause sata_link_hardreset() to
return 0, with online == false.

If that is the case ata_do_reset() would return 0, and
ata_eh_followup_srst_needed() (returns true only if -EAGAIN) would return false.

Which should eventually cause us to retry another hard reset, as long as
tries <= max_tries.


By making sata_link_hardreset() return -EAGAIN, the difference I see is that
we will for a software reset followed by the hardreset, but you commit message
did not mention that.

So, my question is, why is it not sufficient to retry another
hardreset/COMRESET?

Does it work to only do a hardreset (without if a follow up softreset) if you
increase the deadline?


Kind regards,
Niklas