> ioctl(3, SNDCTL_TMR_START or TCSETS, {B921600 -opost -isig -icanon -echo ...}) = 0
It's certainly trying
>
> ...set 921K using TCSETS/B921600... and kernel says ok, but ...
Careful: termios is one of those "gotcha" ioctls. It returns 0 to say
"stuff happened" and returns a termios struct which contains the results
- which may not be what you requested.
So a set to an unsupported rate (too high for the chip clock) will
produce a response of 0 and return the baud rate you actually got given.
> ...we are still at 115200... I wonder if 921600 is the right speed to
> use after all? Any other speeds I should try? (and can 400MHz arm
> handle 921K on serial line?)
It's pushing it on an x86 with a 16550A. You've got about 14 character
times of worst case latency permitted and 14 x 10 bits isn't a lot at
that rate. Some of the clones have much bigger FIFOs so it may depend
what you actually have.
Alan
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