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From: "David S. Miller" <davem@davemloft.net>
To: sparclinux@vger.kernel.org
Subject: Re: [PATCH] SunSAB console problems in 2.6.x
Date: Fri, 27 Aug 2004 23:39:03 +0000	[thread overview]
Message-ID: <20040827163903.0141f798.davem@davemloft.net> (raw)
In-Reply-To: <20040825233247.237c1fb1.davem@redhat.com>

On Sat, 28 Aug 2004 00:34:12 +0100
"C.Newport" <crn@netunix.com> wrote:

> FWIW, I saw this problem in a completely different non-linux context
> a while ago. It is possible, if the code is tight enough, for modern fast
> processors to overwrite the character in a USART transmit register
> before the USART has moved it down the internal buffer. 
> Introducing a suitable delay fixed it.

We protect this by spinning on the sunsab control register waiting
for it to say "character sent and FIFO empty, ready for next char".

It's busted udelay() on sparc64 which is causing this problem.

  parent reply	other threads:[~2004-08-27 23:39 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-08-26  6:32 [PATCH] SunSAB console problems in 2.6.x David S. Miller
2004-08-26  8:31 ` Ralph Mitchell
2004-08-26 13:23 ` Ben Collins
2004-08-26 17:01 ` Ben Collins
2004-08-26 18:05 ` Ralph Mitchell
2004-08-26 20:19 ` David S. Miller
2004-08-27  0:43 ` Joshua Kwan
2004-08-27  1:10 ` David S. Miller
2004-08-27 10:30 ` Ralph Mitchell
2004-08-27 19:19 ` David S. Miller
2004-08-27 22:29 ` David S. Miller
2004-08-27 23:24 ` Joshua Kwan
2004-08-27 23:24 ` David S. Miller
2004-08-27 23:25 ` David S. Miller
2004-08-27 23:34 ` C.Newport
2004-08-27 23:39 ` David S. Miller [this message]
2004-08-28  0:01 ` Joshua Kwan
2004-08-28  0:04 ` David S. Miller
2004-08-28  7:06 ` Ralph Mitchell

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