Re: [smartmontools-support] inactive SATA drives won't stay in standbyor sleep, PATA models did. (fwd)

[Mikael Pettersson]

Tejun Heo writes:
 > Hello,
 > 
 > Mikael Pettersson wrote:
 > > Tejun Heo writes:
 > >  > Hello, Mikael.
 > >  > I would put this into ->hardreset itself as the controller can also
 > >  > get out of sync with reality during reset.
 > > 
 > > The only thing I see going on between prereset and (hard/soft)reset
 > > is an optional freeze, so I don't see why moving the pdc_reset_port()
 > > into the beginning of hardreset() would make any difference.
 > > 
 > > sata_promise currently uses the ->hardreset and ->softreset inherited
 > > from ata_sff_port_ops, so it would need to override both to ensure that
 > > we always do pdc_reset_port() before libata does its thing. That's why
 > > I felt doing that in ->prereset would be the right solution.
 > 
 > Hmm.. reset sequence goes on like the following.
 > 
 >  1. prereset
 >  2. hardreset, if fail, retry
 >  3. follow-up softreset if requested, if fail, goto #2
 >  4. postreset, if successful
 > 
 > So, if some PHY event happens while the reset is waiting for device
 > readiness and makes the controller state go out of sync with the
 > drive.  ->prereset() will NOT be called for the following retry.

I see. Ok, then I'll forget about ->prereset and bind ->hardreset to
code which does pdc_reset_port() before invoking sata_sff_hardreset().

Thanks for your input.

/Mikael
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