Error reading from istream: Error reading from file descriptor: No such device

[Bjørn Mork]

Dan Williams <dcbw at redhat.com> writes:
> On Tue, 2020-03-10 at 12:02 +0000, Nicolas RENAULT wrote:
>> Hi,
>> 
>> so no one here have an idea about these line ?
>
> Bjorn might. But that's a pretty low-level, driver-type problem.

I don't know much more that what those messages say: Our interrupt URB
callback got EPROTO from the USB core.  The "0 bytes" messages are sort
of implied since there should be no data transferred with errors.

According to
https://www.oreilly.com/library/view/linux-device-drivers/0596005903/ch13.html
the meaning of EPROTO in this context (URB callback) is one of:

 * A bitstuff error happened during the transfer.
 * No response packet was received in time by the hardware.

I assume the latter is the case here, given the disconnect.

Either way I don't really know what to do with EPROTO in a URB callback.
The cdc-wdm (and qmi_wwan/cdc_mbim) driver continues processing the URBs
as before, hoping that it is a temporary thing.  But in this case it's
obviously related to the disconnect and there is nothing we can do about
that.

So in short: These messages are unecessary log noise here.  But I
wouldn't feel comfortable completely ignoring an error status either.



Bjørn