It appears the kernel automatically "fixes" this mistake and it works.
the transfer in question is an interrupt transfer and should be submitted
as such. Do that in order to make things more correct and so that the
test can run.
This matches the expectation. i.e. we return no-match and we do not
return a scanned print as we don't have anything for it. If we did
indeed return a scanned print, then fprintd would try to delete it
during enroll and would then fail.
Note that we do *not* return a DATA_NOT_FOUND error in the storage
device if the print does not exist. This is because not all devices
support reporting this error. It is therefore more sensible to handle it
gracefully and expect test setups to set the error explicitly for
We only allow suspending while we are in the interrupt transfer stage.
To suspend, we cancel the interrupt transfer and at resume time we
This has been tested to work correctly on an X1 Carbon 8th Gen with
suspend mode set to "Windows 10" (i.e. S0ix [s2idle] and not S3 [suspend
to RAM]). With S3 suspend, the USB root hub appears to be turned off or
reset and the device will be unresponsive afterwards (if it returns). To
avoid issues, libfprint disables the "persist" mode in the kernel and
we'll see a new device instead after resume.
The assumption here is that in most cases, we will just cancel any
ongoing operation. However, if the device choses to implement
suspend/resume handling and it returns success, then operations will not
Note that suspend/resume requests cannot be cancelled.
Devices that are considered to never run hot will have FEATURE_ALWAYS_ON
set. If set, the UI can safely assume that it is fine to run fingerprint
authentication in the background without other user interaction.
This will allow libfprint to cancel operations internally in the future.
If the internal cancellation method is used, then the private
current_cancellation_reason variable must be set to the GError. This
error will be returned when set.
This temperature model has three states:
Device drivers can define the time it requires for the device to get HOT
and COLD. The underlying model assumes an exponential warming and
cooling process and enforces a cool-off time after the device has
reached the HOT state. This cool down period is however shorter than the
specified time in the driver.