Re: sda

[Tejun Heo <htejun@gmail.com>]

Hello,

Mark Lord wrote:
> What I did back in 2007 was, implement hot plug/unplug for ICH5,
> done by polling the PCS bits.
> 
> It works, and is reportedly quite reliable, even though there is still a
> tiny theoretical loophole where the chipset could lock up.
> 
> The glitch on ICH5, at least, is that the PCS bits work fine for detecting
> drive insertions, but not drive removals.  To detect a drive removal,
> one has to first toggle the enable line (1..0..1) in PCS, and then wait
> for the PHY to try and sync up afterwards (microseconds).

Having hardreset around is helpful whether hotplugging works or not. 
Can you please tell me more about the theoretical loophole?

> The code didn't go upstream because it conflicted somewhat with the pending
> hotplug polling framework you had in development at the time.  :)
> 
> What's the scoop with that now, anyways?  The sata_mv driver will 
> eventually
> want hotplug polling to deal with port multiplier ports -- it cannot use 
> AN.

Heh... That was blocked on sysfs nodes and as time goes by it went down 
through the rabbit hole.  MV can't do AN?  Have you taken a look at how 
ahci implements AN?  It doesn't really support AN.  It just looks at 
what FIS it received and tries to emulate the notification, which BTW 
isn't 100% accurate as the receive area can be overwritten 
asynchronously but it works good enough.  Maybe MV can do similar?

-- 
tejun