Re: [patch 1/1] ppc: Possible bug fix for FCC driver

On Tue, 6 Mar 2007 12:03:57 +0100
Cedric Pontois wrote:

Hi Vitaly,

The problem seems to be similar in recent kernels
(/drivers/net/fs_enet/mac-fcc.c). The transmit clock is inverted (TCI
bit set). The packets are well received, transmitted packets go out
(tx counter is ok), unfortunately as the clock is inverted (TCI) the
data are not correctly received by the other side. The FCC works in
100Mbps (luck?) but doesn't in 10Mbps. I solved this problem by
removing the TCI bit set as described in the patch. Actually, this
problem depends also of the Ethernet phy used on board.

IIRC it worked for us with Davicom PHY on 10 MBps on one of 8260-like...
 
Well I give it a try once more with the recent kernel, but anyway if you think 
you've located and fixed root cause, do (and test) a patch against recent kernel,
send it to me cc'ing netdev and linuxppc-embedded, and I'll push it along
if it is not breaking existing boards.

-Vitaly

Cedric

-----Original Message-----
From: Vitaly Bordug [mailto:vbordug@ru.mvista.com] 
Sent: mardi 6 mars 2007 10:42
To: Li Yang-r58472
Cc: Pontois, Cedric UMTS (CEZ:8Z10); dmalek@jlc.net;
linux-kernel@vger.kernel.org; linuxppc-embedded@ozlabs.org
Subject: Re: [patch 1/1] ppc: Possible bug fix for FCC driver


On Tue, 6 Mar 2007 10:23:43 +0800
Li Yang-r58472 wrote:

quoted

Hi Cedric,

For ppc embedded related patches, please also cc: 
linuxppc-embedded@ozlabs.org.

quoted

We use a kernel 2.6.14 on PPC platform (MPC 8555). The FCC driver

works

To submit a kernel patch upstream, the patch should be against the 
latest kernel version which is 2.6.21-rc now.

quoted

well with a 100Mbps link. But it doesn't with a 10Mbps link. To 
solve it, I modified the GFMR register init: removed TCI bit and
set

quoted

quoted

CRC32

bit

quoted

instead of.

I don't know how these bits caused the 10M link issue.  Do you have 
any reasoning?

quoted

	Signed-off-by: Cedric Pontois [off-list ref]

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--

quoted

-----

diff -ruN pa-original/arch/ppc/8260_io/fcc_enet.c

The fcc code in 8260_io has been obsoleted by fs_enet driver
(drivers/net/fs_enet). It is known to work with 85xx at least in
recent kernels. If it does not for some reason, please letus know.

Thanks,

-Vitaly