[libhid-discuss] unable to get input report

[Charles Lepple]

On Jan 13, 2009, at 11:47 AM, stdht.inbox at gmail.com wrote:

> Hello, Charles.
>
> rawhid = linux/hiddev.h

Oh, OK. When we first started writing libhid, the hiddev interface  
did not handle the nested collections necessary to read information  
from USB UPSes. It has changed since then, but some UPSes are still  
blacklisted as a result.

> besides, I overworked..
> So my devices sends me scanned info in each interrupt report.
> I call hid_interrupt_read in loop (timeout=5000)
> I works ok! it works good at 2.6.x and 2.4.31 kernel...
> BUT!!! I tried my utility under linux 2.4.25 (my target
> embedded device). The result is bad. In the loop after the first
> hid_interrup_read timeouts and after that moment all subsequent calls
> to hid_interrup_read fail!!

Sounds like something specific to your platform. Have you checked to  
see how long it waits before declaring a timeout?

> WARNING: hid_interrupt_read(): failed to get interrupt read from  
> device 002/002[0]: error submitting URB: No such device or address
> hid_interrupt_read failed with return code 21
>   TRACE: hid_interrupt_read(): retrieving interrupt report from  
> device 002/002[0] ...
> host/usb-uhci.c : ENXIO 40010280, flags 0, urb c71e2d70, burb c54ee800
> USB error: error submitting URB: No such device or address

This error does not sound good - it's like the device disconnected  
itself. Check to see if it still has the same device address in  
'lsusb' (or /proc/bus/usb/devices)

> code:
> while(1) {
>   ret = hid_interrupt_read(hid, 0x82, buf, 64, 5000);
>   if (ret != HID_RET_SUCCESS) {
>        printf( "hid_interrupt_read failed with return code %d\n",  
> ret);
>

You should be able to do the following:

    printf( "hid_interrupt_read failed with return code %d (%s)\n",  
ret, hid_strerror(ret));

-- 
Charles Lepple