[Nut-upsuser] tracing a problem with newhidups

[Rodrigo Ventura]

On Thursday 06 July 2006 20:15, Arnaud Quette wrote:
> a good try, and amount of effort.
> Sadly, notifications are on the PIPE_INTERRUPT

Ok, let's do it again.

HIDGetEvents() calls libusb_get_interrupt() with size=20 (hardcoded), which 
calls usb_interrupt_read(), then usb_urb_transfer(), which sets 
urb.buffer_length=20, going down the ioctl (as uurb), where the kernel urb 
struct gets urb.transfer_buffer_length=20. Then, uhci_submit_interrupt() 
checks that field with

--------------------
        if (urb->transfer_buffer_length > usb_maxpacket(urb->dev, urb->pipe, 
usb_pipeout(urb->pipe)))
                return -EINVAL;
--------------------

What is the endpoint max packet size? According to /proc/bus/usb/devices

C:* #Ifs= 1 Cfg#= 1 Atr=40 MxPwr=  0mA
I:  If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub
E:  Ad=81(I) Atr=03(Int.) MxPS=   8 Ivl=255ms
T:  Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  2 Spd=1.5 MxCh= 0
D:  Ver= 1.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs=  1
P:  Vendor=0463 ProdID=ffff Rev= 1.00
S:  Manufacturer=MGE UPS SYSTEMS
S:  Product=Evolution
S:  SerialNumber=AF3G03062

C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr= 40mA
I:  If#= 0 Alt= 0 #EPs= 1 Cls=03(HID  ) Sub=00 Prot=00 Driver=(none)
E:  Ad=81(I) Atr=03(Int.) MxPS=   8 Ivl=20ms

Assuming that MxPS means max packet size, it seems to be 8, which is
lower than 20, and therefore it looks like the EINVAL error comes from
there. Am I going in the right direction this time?


> If something is not working, you can try to reset the communication: power
> off the UPS, then unplug its power cable, wait (at least) 10 seconds and
> replug/restart all.

Well, that's something I'd like to avoid, since all the institution servers 
are fed by the UPS.

Cheers,

Rodrigo

-- 

*** Rodrigo Martins de Matos Ventura <yoda at isr.ist.utl.pt>
***  Web page: http://www.isr.ist.utl.pt/~yoda
***   Teaching Assistant and PhD Student at ISR:
***    Instituto de Sistemas e Robotica, Polo de Lisboa
***     Instituto Superior Tecnico, Lisboa, PORTUGAL
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