Clearing stalls: usbd_xfer_set_stall vs usbd_do_clear_stall_callback

[Hans Petter Selasky]

On Thursday 05 May 2011 09:15:09 Trevor Blackwell wrote:
> 8.2-STABLE. I'm willing to run whatever.
> 
> I suspect the problem I'm having is the same as this:
> http://kerneltrap.org/mailarchive/linux-usb/2009/5/15/5761363
> 
> I can manually kick it out of the wedged state by sending a RESET_TT
> transaction to the hub with usbconfig -d ugen1.3 do_request 0x23 0x09
> 0x0000 0x0001 0
> 
>   (UT_WRITE_CLASS_OTHER, UR_RESET_TT)
> 
> I'm working on adding code to do this. My current hack is to do it from
> uhub_explore. When my driver tries to do a clear-stall and gets a timeout
> error from the clear-stall, it sets a flag on the parent_hs_hub to request
> a RESET_TT. uhub_explore notices the flag and does it.
> 
> Possibly I could also add it to usb_do_clear_stall_callback, but I don't
> think I can call usb_do_request from inside a callback.
> 
> Any suggestions?

Hi,

I think it is best to do this from the root HUB thread, then the operation 
gets properly serialised. Then the clear-stalls requests will simply be 
pending until normal operation is established.

Could a control endpoint timeout in general imply that the parent High Speed 
HUB, if any, should be reset?

--HPS