Re: [PATCH] libata: Integrate ACPI-based PATA/SATA hotplug - version 2

[Tejun Heo <htejun@gmail.com>]

Matthew Garrett wrote:
> On Fri, Sep 21, 2007 at 11:35:05AM +0900, Tejun Heo wrote:
>> Matthew Garrett wrote:
>>> The alternative would be to add a flag to the ap structure indicating 
>>> whether the hotplugging is handled by the firmware or not. If we find a 
>>> reference to a controller or port in the firmware tables, it probably 
>>> indicates that the hardware has opinions about how this should be 
>>> handled. We might be safer leaving it to the firmware in those cases, 
>>> and using that flag to skip the controller-specific hotplug code.
>> I was thinking the other way around.  I'd rather depend on hardware
>> provided events than firmware provided ones.  How about flagging drivers
>> which can do native hoplugging and using ACPI hotplugging only if the
>> driver can't do it natively?
> 
> If the manufacturers have added firmware-level hotswap interrupts, then 
> there's all sorts of insane ways they might have wired the bay up. I 
> don't really trust them to have managed to do so without breaking native 
> hotplug :) It doesn't really matter at the moment, though, since I 
> haven't actually seen any examples of hardware using anything that can 
> manage native hotplug. If anyone out there does have one, it would be 
> nice to get some feedback about what it does.

Maybe just letting both events in is the best idea.  It's not like two
duplicate events are gonna break anything and I don't think many vendors
are gonna implement separate mechanism when the default SATA phy based
one works.

-- 
tejun