On 30/01/08 14:05, Alan Stern wrote:
> It's a bug for Set-Interface to fail.

Yes and not.

>  Following a reset, the device has no reason to fail such a request.
>   

The device doesn't, but you can lose a packet (i.e. CRC error). In this
case the kernel should properly recover. In this case the kernel is
recovering, but the hiddev becomes useless because the device changed
its address. I think the kernel should make this device invalid and
inform a read error as soon as the user space tries to read from it. I
think the application gets notified only if reading in blocking mode.

> I'm not terribly familiar with the hiddev driver, but I think it's not
> a bug that it doesn't report any kind of read error when this happens.  
> The situation should be exactly the same as if you had unplugged the
> HID device -- reads should return an end-of-file indication rather than
> an error.  However I could be wrong about this.
>   

It currently informs an error if the device is unplugged. IMHO that's
the right thing to do, the user space application can then close the
file handle and try to open it again, if it fails the application can
then try to interact with the user asking to replug the device.

Regards, SET

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