Re: serial.c (modem-fcr)
Rogier Wolff (R.E.Wolff@BitWizard.nl)
Wed, 27 Oct 1999 15:21:39 +0200 (MEST)
Theodore Y. Ts'o wrote:
> Date: Wed, 27 Oct 1999 09:01:46 +0200 (MEST)
> From: kees <kees@schoen.nl>
>
> While I'm reading the datasheet for the (EXAR) ST16550, this is an uart
> with fifo's, I'm beginning to believe that the serial driver should
> maintain a copy of this write-only register.
> I understand (from this info) that when bits that are programmed i.e. FIFO
> RX or TX trigger level the others must be re-written or they will be
> lost(reset).
>
> The contents of the FIFO Control Register (FCR) is recalculated each
> time we need it in change_speed(); since it's relatively trivial to
> recalculate it, there's no point in saving a copy of it somewhere.
By the way, the OX16C954 has a "readable FCR" register, that you can
read to get the current value....
Roger.
--
** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2137555 **
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