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* Serial console issues.
@ 2007-02-12 20:39 Andy Kennedy
  2007-02-12 20:56 ` David Lang
  0 siblings, 1 reply; 7+ messages in thread
From: Andy Kennedy @ 2007-02-12 20:39 UTC (permalink / raw)
  To: linux-kernel

For those of you who are on BusyBox's mailing list, you've already seen 
this -- I was sent here for help.

Specs:
Linux:  2.6.18
Bootloader:  SysLinux
Init:  BusyBox (ver 1.4.0) init.
Kernel command line: console=ttyS0,115200,n,8,1
System: VersaLogic 568 (STD80/STD32 Bus, i386 based computer)
Issue:  Booting on "System" I get perfect printk's to the serial 
console.  When the init takes over (from within an initrd), the console 
begins to miss characters.  I can still send write commands through the 
console, however, the output of these commands is garbled.  The really 
odd part is when the init releases control (is killed by Linux), or when 
a printk is issued, the console prints perfectly again.  The next really 
strange part about this is that changing "System" to my laptop -- no 
problems PERIOD. 

The BusyBox list directed me to LKML as this is a wider base of users 
that may have experienced the same problem and could provide me an answer.

Thanks in advance for the help (and sorry for asking such a non-related 
issue on the LKML),
Andy

^ permalink raw reply	[flat|nested] 7+ messages in thread
* Re: Serial console issues.
@ 2007-02-14 23:11 akennedy
  2007-02-15  0:24 ` Alan
  0 siblings, 1 reply; 7+ messages in thread
From: akennedy @ 2007-02-14 23:11 UTC (permalink / raw)
  To: linux-kernel

In a previous post I incorrectly stated that my serial port is a
TI16750, as this is what /proc/tty/... revealed to me.  After
re-reading the product manual, I see that this is actually a 16550. 
Since Linux is seeing this port as a 16750, could that explain why I'm
seeing missing characters in the transmission.  After doing some
research, I found that the 16750 has a 64-byte buffer, whereas I know
this to only have a 16-byte buffer.

If my assumptions are correct and Linux is detecting this serial port
incorrectly, how can I force the serial driver to see this a 16550?

Thanks again for any assistance you can provide,

Andy Kennedy


^ permalink raw reply	[flat|nested] 7+ messages in thread
* RE: Serial console issues.
@ 2007-02-15  0:39 akennedy
  2007-02-15 10:49 ` Russell King
  0 siblings, 1 reply; 7+ messages in thread
From: akennedy @ 2007-02-15  0:39 UTC (permalink / raw)
  To: Alan; +Cc: linux-kernel

> > In a previous post I incorrectly stated that my serial port is a
> > TI16750, as this is what /proc/tty/... revealed to me.  After
> > re-reading the product manual, I see that this is actually a 16550.
> > Since Linux is seeing this port as a 16750, could that explain why I'm
> > seeing missing characters in the transmission.  After doing some
> > research, I found that the 16750 has a 64-byte buffer, whereas I know
> > this to only have a 16-byte buffer.
>
> The autodetect is pretty solid so you may well find the chip is 16750
> compatible, 16550A is what is usually listed because it is what people
> look for.
>
> > If my assumptions are correct and Linux is detecting this serial port
> > incorrectly, how can I force the serial driver to see this a 16550?
>
> man setserial

Well, this is the most bastardized sucker I've ever seen. . . I have had
no end of trouble with it (couldn't even get a boot loader to work with
it - had to write my own).  And, as luck would have it, the serial port
is no different.  Using setserial, I changed the type of this port to a
16550A and all my problems went away.  The question now remains:  How
can I FORCE the Linux serial driver to see this as a 16550A -- As I
before stated, I know that this has a 16-byte buffer.  Therefore, the
16750 with its mammoth buffer size is killing this serial port.  Short
of modifying the kernel (which I'd rather not do) or including the
setserial with the kernel image (also I'd rather not do as I only have
2.3 MB of storage on this device) I need a command line parameter to
control the serial line -- is there one?  A build option?  PLEASE
SOMETHING???

Andy


^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2007-02-15 10:49 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2007-02-12 20:39 Serial console issues Andy Kennedy
2007-02-12 20:56 ` David Lang
2007-02-13 20:20   ` Andy Kennedy
2007-02-14 23:11 akennedy
2007-02-15  0:24 ` Alan
2007-02-15  0:39 akennedy
2007-02-15 10:49 ` Russell King

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