On Sat, Jun 02, 2007 at 10:49:44AM -0400, Alan Stern wrote:
> Then later on, when the hub driver is resumed it will see the flag and
> disconnect all the devices below the root hub.
> For instance, you could force ohci-hcd to report connect-change events
> on all the ports. Perhaps it does something like that anyway, in which
> case you wouldn't have to worry about it.
After studying the code for two evenings, I'm quite sure it does that
already.
A comment in ohci-hcd.c:ohci_restart reads:
/* mark any devices gone, so they do nothing till khubd disconnects.
* recycle any "live" eds/tds (and urbs) right away.
* later, khubd disconnect processing will recycle the other state,
* (either as disconnect/reconnect, or maybe someday as a reset).
*/
usb_root_hub_lost_power marks the ports as gone, khubd will disconnect them.
After restarting the chip, khubd will cause them to be detected again.
This is also what I can watch in the logs:
ohci_hcd 0001:10:15.1: OHCI Unrecoverable Error, scheduling NEC chip restart
usb usb2: root hub lost power or was reset
usb 2-2: USB disconnect, address 2
input: appletouch disconnected
usb 2-2: new full speed USB device using ohci_hcd and address 3
usb 2-2: configuration #1 chosen from 1 choice
input: Apple Computer Apple Internal Keyboard / Trackpad as /class/input/input16 on usb-0001:10:15.1-2
input: appletouch as /class/input/input17
input: Apple Computer Apple Internal Keyboard / Trackpad as /class/input/input18 on usb-0001:10:15.1-2
(Actually, I added some code to trigger the error handling code, reliably
reproducing it otherwise is impossible.)
Thanks,
Michael
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