From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Lennart Sorensen <lsorense@csclub.uwaterloo.ca>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Strange transmit corruption in jsm driver on geode sc1200 system
Date: Fri, 25 Aug 2006 22:20:17 +0100 [thread overview]
Message-ID: <1156540817.3007.270.camel@localhost.localdomain> (raw)
In-Reply-To: <20060825203047.GH13641@csclub.uwaterloo.ca>
Ar Gwe, 2006-08-25 am 16:30 -0400, ysgrifennodd Lennart Sorensen:
> The driver is doing memcpy_toio to tranfer data to the transmit FIFO
> (which is a 64byte memory mapped block of memory on the PCI bus as far
> as I can tell). The data in the transmit queue is in the right order
That should be staying in order unless the device memory is mislabelled
and prefetchable etc.
> being passed to memcpy_toio, but somehow by the time it is in the uart
> and goes out the transmiter, every 4th byte is moved 3 bytes back.
What happens if you swap the memcpy_toio with while() writeb() ?
> I read something about the geodes doing memory write reordering, but
> that it is supposed to magically not screw up PCI writes. I have no
> idea if it is or not though.
They do a lot of stuff but it should not affect the PCI side and I'd
expect it to do other things than byte lane re-ordering.
> Does anyone have any suggestions for something to try?
Is the buffer 32bit aligned ?
next prev parent reply other threads:[~2006-08-25 20:58 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-25 20:30 Strange transmit corruption in jsm driver on geode sc1200 system Lennart Sorensen
2006-08-25 21:20 ` Alan Cox [this message]
2006-08-25 21:03 ` Lennart Sorensen
2006-08-25 21:24 ` Alexey Dobriyan
2006-08-25 21:57 ` Lennart Sorensen
2006-08-28 17:30 ` Lennart Sorensen
2006-08-28 18:11 ` Lennart Sorensen
2006-08-28 19:09 ` Alan Cox
2006-08-28 19:18 ` Lennart Sorensen
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