16650 UART support ?

16650 UART support ?

Post by Wayne Whitn » Tue, 06 Aug 1996 04:00:00



Hello,

Does the Linux serial driver support a 16650 UART?  For example, it
has a longer FIFO than a 16550A, I believe, but using the longer FIFO
requires driver support.  If it's not currently supported, is anyone
working on it?  Thanks very much.

Yours,
Wayne Whitney

 
 
 

16650 UART support ?

Post by Eric Vough » Wed, 07 Aug 1996 04:00:00


Quote:> Does the Linux serial driver support a 16650 UART?  For example, it
> has a longer FIFO than a 16550A, I believe, but using the longer FIFO
> requires driver support.  If it's not currently supported, is anyone
> working on it?  Thanks very much.

Apparently, the larger FIFOs on the 16550 are not supported under Linux
(and will not be) due to bugs in many of the 16550 implementations. Most
of the 16550's just don't work correctly and are therefore treated as
ordinary 16450's. The 16550A's are fully supported.

 
 
 

16650 UART support ?

Post by bill davids » Wed, 07 Aug 1996 04:00:00




| > Does the Linux serial driver support a 16650 UART?  For example, it
| > has a longer FIFO than a 16550A, I believe, but using the longer FIFO
| > requires driver support.  If it's not currently supported, is anyone
| > working on it?  Thanks very much.
|
| Apparently, the larger FIFOs on the 16550 are not supported under Linux
| (and will not be) due to bugs in many of the 16550 implementations. Most
| of the 16550's just don't work correctly and are therefore treated as
| ordinary 16450's. The 16550A's are fully supported.

I can't find any relation between this answer and the question, so
I'll answer the original question. There was support for the 16650
at one time, but there was a bug in it, possibly due to the doc
being either unclear or just flat wrong. A fix was posted which made
the chip work as intended. Instead of including the fix, the support
for the 16650 was removed. I believe there is a 16750 as well.

This info from postings here and having applied the patch to 1.2.13
to drive my one and only 16650. All facts modulo my recollection of
what happened some time ago.
--

"As a software development model, Anarchy does not scale well."
                -Dave Welch

 
 
 

16650 UART support ?

Post by Theodore Y. Ts' » Thu, 08 Aug 1996 04:00:00



   Date: 6 Aug 1996 22:13:39 GMT

   I can't find any relation between this answer and the question, so
   I'll answer the original question. There was support for the 16650
   at one time, but there was a bug in it, possibly due to the doc
   being either unclear or just flat wrong. A fix was posted which made
   the chip work as intended. Instead of including the fix, the support
   for the 16650 was removed. I believe there is a 16750 as well.

There were bugs in the original StarTech 16650 chip --- I have one of
the original chips, plus the original spec sheet, and it was definitely
broken; even its 16550A compatibility mode was broken.  That's why the
current Linux kernel code detects the original 16650 chip, and treats it
as if it were a 16450, because the original 16650 FIFO handling was
complete garbage.

There has since been a quiet change in the 16650 chip, which StarTech
did without making any fanfare about it.  Someone has sent me the latest
spec sheet, and it's significantly different from the original spec
sheet.  I just simply haven't had the time to figure out how to tell the
original, broken 16650 chips from the new, working 16650 chips.
Startech didn't help, because they didn't acknowledge that they made the
change, and haven't put in any application notes for how to distinguish
a broken 16650 from a working 16650.

(Contrast this with what National Semiconductor did when they
accidentally broke FIFO handling in the original 16550; they publically
admitted their error, and issued the 16550A, and told you how to
dintinguish between a 16550 and a 16550A.)

I do have a sample of the new 16650 chip from Startech, but I haven't
had the time to try to make it work.  Quite frankly, it's not clear to
me how useful the extra 16 bytes in its receive FIFO really is, so it
hasn't been high on my priority list.  The fact that StarTech hasn't
made it easy to distinguish between new and broken chips hasn't helped
either.

                                                - Ted

 
 
 

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Hi,

    I have a BitSurfr Pro ISDN adaptor and I'm considering adding a
16650 UART to improve the overall throughput at 128Kbps.  I'm sure that
BitSurfr supports up to 230Kbps throughput and the question is: does
FreeBSD support 16650 UARTs?

Thanks,

Ian Huang

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