Date: Thu, 19 Apr 2007 14:10:21 -0700 From: Alfred Perlstein <alfred@freebsd.org> To: hackers@freebsd.org, bde@freebsd.org Subject: serial help ? Message-ID: <20070419211021.GH69188@elvis.mu.org>
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I'm working on some custom hardware and I'm getting garbled console
output.
I noticed that siocntxwait looks like this:
static void
siocntxwait(iobase)
Port_t iobase;
{
int timo;
/*
* Wait for any pending transmission to finish. Required to avoid
* the UART lockup bug when the speed is changed, and for normal
* transmits.
*/
timo = 100000;
while ((inb(iobase + com_lsr) & (LSR_TSRE | LSR_TXRDY))
!= (LSR_TSRE | LSR_TXRDY) && --timo != 0)
;
}
Shouldn't there be some sort of DELAY in there?
My platform has an emulated serial device in hardware, so it
may be that the loop could run a LOT faster than transmit can
happen...
any ideas of what the DELAY should be?
--
- Alfred Perlstein
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