On 09/17/13 11:06, Harald Schmalzbauer wrote:
  Bezüglich Hans Petter Selasky's Nachricht vom 17.09.2013 10:57
On 09/17/13 10:47, Lev Serebryakov wrote:
Hello, Harald.
You wrote 17 сентября 2013 г., 12:46:25:

HS> The Y is the device addr @ bus #X.
    Oh :)

HS> Same posted some seconds ago :-)
    Yep, exactly the same pattern.


Could you show the configuration descriptor for your device?

usbconfig -d X.Y dump_curr_config_desc

Shall we switch to non-list-comm?


That's OK.

Hmm, in my case, this 4-port-serial-USB-hub will be used as console
concentrator. So most time it's doing nothing, just feeding tmux with
consoles output. What latency are we talking about? Less than a some
milliseconds should be fine.
What I'm curious about is why my prolific USB-serial converter doesn't
generate these high irqs.

Try this patch and see what happens:

--- umcs.c      (revision 255492)
+++ umcs.c      (local)
@@ -230,6 +230,7 @@
                .bufsize = 0,           /* use wMaxPacketSize */
                .callback = &umcs7840_intr_callback,
                .if_index = 0,
+               .interval = 20, /* ms */

BTW: I see that the umcs driver shouldn't do synchronous control transfers from the USB interrupt transfer callback. This should be postponed into some worker thread, for example the USB explore thread. See USB audio driver for an example.

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