29 Aug
2013
29 Aug
'13
10:59 a.m.
Am Donnerstag, 29. August 2013, 10:47:46 schrieb Dmitry Timoshkov:
Wolfgang Walter <wine(a)stwm.de> wrote:
Maybe for tests. But the application which fails here (with vanilla wine)
hangs because it waits for EV_TXEMPTY.
Basically it writes data to several serial ports, then write to files and then
waits for the EV_TXEMPTYs.
Regards,
--
Wolfgang Walter
Studentenwerk München
Anstalt des öffentlichen Rechts
Abteilungsleiter IT
Leopoldstraße 15
80802 München
I think that happens:
* application writes data to com port.
* all is written, serial buffer is empty
* application calls WaitCommEvent()
* wait_on() is called
* wait_on() calls get_irq_info()
* get_irq_info() sets commio->irq_info->temt = 1
* wait_on() calls check_events() and uses sets commio->irq_info for old an
new * so old->temt == new->temt and EV_TXEMPTY is not set
* if there are no other events (in real world basically EV_RXCHAR):
* wait_for_event() is startet with commio->irq_info->temt set to one
* wait_for_event() calls get_irq_info() with new_irq_info()
* get_irq_info() sets new_irq_info->temt = 1 because the buffer is still
empty * wait_for_event() calls check_events() with new_irq_info and
commio->irq_info * again check_events() will not set EV_TXEMPTY as both
have temt == 1
It seems that we do not recover from that hang.
Please correct me if I misread the code and I'm wrong.
I think it's better if WaitCommEvent() returns with EV_TXEMPTY even if
there
has no new data been sent in between:
That means that WaitCommEvent(EV_TXEMPTY)
without any prior WriteFile
would always return success and signal the EV_TXEMPTY event. My tests
show that WaitCommEvent(EV_TXEMPTY) fails with a timeout in this case.
Since the serial device is very slow it should be unlikely that after
successful WriteFile() with some data WaitCommEvent() sees an already
empty transmitter's output queue.