Thanks Alan,
that was very helpful.
/Bernd
Alan Stern wrote:
On Tue, 14 Jul 2015, Bernd Porr wrote:
I've got a question regarding ISO transfer. If the firmware is not
providing data is the ISO urb returning zero packet length and if yes
how can I check that in the driver? I'm working on a solution for my
USBDUX driver where the ADC for example takes 800us to measure all data
so that a couple of zero length packets were generated until new data
has been created.
I assume you're talking about isoc-IN transfers where the device either
sends a 0-length packet or doesn't send any packet at all. When that
happens, the corresponding urb_iso_packet_descriptor structure will
contain 0 for .actual_length and either 0 for .status (if a 0-length
packet was received) or -EXDEV for .status (if no packet was received).
Your driver can check these values in the URB's completion routine.
Alan Stern
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