[PATCH 1/5] use a correct timeout in test_waittxempty

Wolfgang Walter wine at stwm.de
Thu Sep 5 03:29:54 CDT 2013

On Thursday 05 September 2013 10:32:15 Dmitry Timoshkov wrote:
> Wolfgang Walter <wine at stwm.de> wrote:
> > When we send 17 bytes with 150 baud, no parity, one stop bit then
> > we need to wait at least 17*10/150 seconds > 1000 ms
> Under Windows with both real COM-port and USB-serial cable this test takes
> no longer than 890 ms, usually it's even shorter like 875 ms. Testbot VMs
> also don't fail this test. If under Wine it takes > 1000 ms for you then
> probably there is a bug somewhere.

How can that be? If you send 17 bytes which expands to 170 raw bits and you 
only sent 150 bits/s?

Maybe you are using a virtual machine or your com port does not support 150 
baud and chooses a different speed. Or you use a UART with a large buffer and 
which already signals TX-EMPTY even if it is still sending from an internal 
buffer. But one should not rely on that.

I used a real com-port, by the way, and had a com-port-analyzer adapted to it. 
It exactly sends 150 bits per second which means 15 data-bytes per second.

Wolfgang Walter
Studentenwerk München
Anstalt des öffentlichen Recht
Abteilungsleiter IT
Leopoldstraße 15
80802 München

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