[libhid-discuss] Missing reports in hid_interrupt_read()

[Jacques Dirac]

Hi,

My program reads reports from a device using the hid_interrupt_read()
function, but when reports follow each other quickly, they could get
lost (not returned by hid_interrupt_read()).

With help of the developer of the device we could get some information
about what is going on in the device:
- the device has a queue for the IN-reports, so a report is not lost
in the device
- in each report there is a value that counts how many times the
device has placed a report in the IN-report-buffer
- in each report there is a value that contains the time that the last
IN-report waited in the register to be fetched by the host

With this information we see that:
- the device puts all messages in the IN-report-buffer, but not all
messages could be fetched with hid_interrupt_read()
- a lost message is fetched (by something) in <10ms (this is the same
time as the other messages)

Then my questions are:
- Is there some routine in libhid (or libusb) that is fetching the
reports from the IN-report-buffer of the device and saves them in a
'buffer' where hid_interrupt_read() is reading from? In my case it
looks like that buffer is overwritten.
- If so, can this be disabled or influenced?
- If not, what else can be going on here?

Hope someone can help to clear things up.

Best regards.