Re: REQ_PM vs REQ_TYPE_PM_RESUME

[Aaron Lu <aaron.lu@intel.com>]

On 01/07/2014 10:50 PM, Phillip Susi wrote:
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> On 1/7/2014 2:49 AM, Aaron Lu wrote:
>> We can modify the device's system resume callback. To better
>> illustrate the idea, I just made two patches to do this and I did
>> some quick tests and didn't find anything wrong.
> 
> That misses one key aspect I was trying to capture: it always leaves
> the disk runtime suspended after a resume.  If the disk spins up on

You mean you want to leave the disk runtime suspended after a system
resume and in the meantime make sure the disk is indeed not spun up?

-Aaron

> its own, as most ata disks do, then the runtime status doesn't
> correctly reflect the actual state of the disk.  This means that
> applications that delay activities due to the runtime pm status to
> avoid waking a disk won't run, and any runtime autosuspend won't kick
> in to actually put the disk back to sleep.
> 
> To do that, you need to be able to issue a REQUEST SENSE and
> conditionally resume the device.  Of course, you can't do that unless
> you first get it into a transitional state, but you can't just request
> a resume and then conditionally fail it.
> 
> 
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