umcs (4-Port-USB-serial) triggering way too much ehci IRQs

Lev Serebryakov lev at
Tue Sep 17 19:06:22 UTC 2013

Hello, Hans.
You wrote 17 сентября 2013 г., 20:04:58:

HPS> I think the adapters use very small buffers. You can try adding
HPS> ".interval = 4" to the other USB configs, above the one you patched, and 
HPS> see what happens. I cannot tell if you will loose characters or not.
 Datasheet promise 2x512 bytes FIFO for each port (on USB level, and typical
16 bytes buffers on UART level, because it emulates 16c550 compatible
UARTs)... Maybe, my setup of these FIFO buffers are not optimal, but
datasheet (even "NDA"-marked onem and I don't mention public, which is total
bullshit) doesn't say anything about configuring these buffers.

// Black Lion AKA Lev Serebryakov <lev at>

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