Re: [RFC][PATCH 4/4] ahci: support hot plug when port/controller isruntime suspended

[Kay Sievers]

On Thu, Dec 15, 2011 at 20:21, Tejun Heo <tj@xxxxxxxxxx> wrote:
> On Thu, Dec 15, 2011 at 09:12:49PM +0800, Lin Ming wrote:
>> I use eSATA to test disk hot plug.
>> With previous 3 patches applied, disk hot plug does not wok
>> when ahci port/controller is runtime suspended.
>>
>> There are 2 cases we need to handle for hot plug:
>>
>> 1. port suspended, controller active
>> Â ÂIs IRQ need to be enabled for port to detect hot plug?
>>
>> 2. port suspended, controller suspended
>> Â ÂWill controller get a PME when hot plug happens?
>>
>> I'm still investigating hot plug support.
>>
>> Anyone has comment?
>
> SATA link detection requires hot wire and keeping wire hot takes
> power.

Oh, hardware in general just sucks. :)

> I think it's fair tradeoff to not support hotplug while
> powersaving is on. ÂWe have warm plug mechanism (the SCSI rescan
> trigger via sysfs) after all. ÂIt would be nice if things like that is
> somehow exported to userland in easy way tho (cc'ing Kay), but I
> frankly don't have much idea where that would fit.

Getting David in the loop. He might have an idea.

Kay
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