Re: serial.c (fifo) (2nd posting)
Rogier Wolff (R.E.Wolff@BitWizard.nl)
Tue, 26 Oct 1999 10:25:46 +0200 (MEST)
Theodore Y. Ts'o wrote:
> Date: Sat, 23 Oct 1999 14:54:37 +0200 (MEST)
> From: kees <kees@schoen.nl>
>
> For programming the FCR register there is stated:
>
> FCR bit 0: logic 0 disable xmit and recv fifo
> FCR bit 0: logic 1 enable xmit and recv fifo;
> THIS BIT MUST BE A LOGIC '1' WHEN OTHER FCR BITS ARE WRITTEN or
> they will NOT BE PROGRAMMED.
>
> I found a few spots where the fcr bits were written but without
> bit 0 SET in the resulting pattern.
>
> I've checked a couple of spec sheets, and yes, this seems to be right.
>
> The two places FCR_ENABLE isn't set while writing to the FCR register is
> where we're trying to clear the FIFO's while resetting the UART, while it
> doesn't seem to have made any difference, it would be good to this
> fixed.
I vaguely remember that clearing that bit was part of the protocol of
clearing the FIFO, but my docs don't directly confirm this.
Be careful, Ted!
Roger.
--
** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2137555 **
*-- BitWizard writes Linux device drivers for any device you may have! --*
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