On 07/16/2014 01:20 PM, Grant Edwards wrote:
I'm working on the regression test appliction I use to test the serial
drivers I maintain, and I've run into a problem with interaction
between tcflow(TCOON/TCOOFF) and XON/XOFF using bog-standard 16x50
UARTs and the normal in-kernel driver.
When I call tcflow(TCOOFF) on a tty device and then write data to that
tty device, the data isn't sent. That's what I expect. But, when an
XON is then received by that port, it does not start the tx data.
Conversly, when a serial port receives an XOFF, it stops sending
data as it should, but a subsequent call to tcflow(TCOON) does not
casue it to start sending data.
Am I misunderstanding how tcflow(TCOxxx) is supposed to interact with
XON/XOFF flow control?
Or is something broken in the tty layer or uart driver?
tcflow(TCOxxx) flow control is independent of IXON flow control.
The union of both flow states determines if the tty can output;
IXON = true IXON = false
START STOP
tcflow(TCOON) on off on
tcflow(TCOOFF) off off off
Regards,
Peter Hurley
PS - The various flow states are not SMP-safe. I'm working to correct that.
--
To unsubscribe from this list: send the line "unsubscribe linux-serial" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
