Hello,
Le lundi 20 mai 2013 09:30:12, Tejun Heo a écrit :
> > Unplugging the drive would, in my understanding, loose the setting if
> > stored at the device level. Is there another way to trigger a new
> > initialisation attempt after changing the setting ?
> > Should I add a "rescan" device attribute ?
>
> But isn't that what we want? We don't really know to which side the
> bridge is attached but given SATA supports hotplug while PATA doesn't,
> it's natural to assume the bridge to be part of the device rather than
> bus and reset the state on device hotplug, no?
Semantically, I agree that the bridge is part of the device.
Putting the knob on the port is just a way I thought about to hold the
configuration before the drive is plugged into the system (because so far I
was focussed on host-side being hot-pluggable, I indeed didn't consider the
opposite situation) so it can be used before libata tries to access the
device.
So it would be something like:
- plug device (or boot up)
-> detection times out, device "half" configured (sysfs node present, drive
not usable)
- cd $DEVICE_IN_SYSFS
- echo 1 > atapi_dmadir
- echo 1 > (rescan|reinit|...)
If it's ok, I'll write a patch to add a rescan write-only file (will also be
independent from the 2 other patches).
I'll certainly need a few days to get it though: I feel I'll have some
difficulty finding the right function to call, and to call it correctly (I
feel interrupt handler & locking, which I'm not familiar with at kernel
level). Pointers welcome !
Regards,
--
Vincent Pelletier
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