This is the mail archive of the
ecos-discuss@sourceware.org
mailing list for the eCos project.
Generic 16x5x serial driver use of transmit FIFO (was: DSR Scheduling Problem)
Nick Garnett <nickg@ecoscentric.com> writes:
> Actually, it doesn't.
I think you're wrong.
> This already happens. pc_serial_putc() returns true or false,
> depending on whether it transmitted the byte. In the 16550 this means
> that it will only return false when the FIFO fills up.
No. LSR bit 5 (THE) is set when the TX FIFO is empty, not when it's
non-full.
> The generic serial code calls the putc() driver routine in a loop to
> transmit bytes until it returns false.
Writing to the THR clears the THE so it will typically return false
after the first byte, and the FIFO will never fill up.
Regards,
--
Daniel Néri <daniel.neri@sigicom.se>
Sigicom AB, Stockholm, Sweden
--
Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss