Re: [PATCH] SATA / AHCI: Do not play with the link PM during suspend to RAM

[Tejun Heo <htejun@gmail.com>]

Hello,

On 08/17/2010 01:19 PM, Rafael J. Wysocki wrote:
> Well, I wonder what the real reason for doing the link power management
> thing at this particular point in the suspend code path is.  It just seems to
> disable the link power management, but then the controller is put into a
> low-power state and is reset from scratch during resume, so I'm not quite
> sure how skipping that code could possibly lead to any problems.

Stranger things have happened in the ATA la-la land. :-) Also, it
makes non-lpm and lpm cases leave the controller and device in
different states when it goes to sleep, which _really_ bothers me.
Combined with the timing dependent nature of DIPM, I worry this might
lead to very obscure issues and would much prefer to make sure
everything is in fixed, known, fully powered state before committing
to any major operations.  I might be paranoid tho.  I'll think more
about it.

> Perhaps we could move the link PM manipulation to the prepare stage
> of suspend?

Yeah, one possibility is that the devices misbehave if they receive
LPM commands while suspended.  Does commenting out sd_suspend resolve
the issue too?

Thanks.

-- 
tejun