Re: [patch 08/16] skge: fix ram buffer size calculation

[Heikki Orsila <shdl@zakalwe.fi>]

On Thu, Nov 15, 2007 at 08:48:58AM -0800, Linus Torvalds wrote:
> This is my commit message for the revert - note the suggested possible 
> fix (but also why I didn't apply it, and why things got reverted).
> 
> 		Linus
> ---
> commit 279e1dab949d33737557babfe9f74e0b74fbe39a
> Author: Linus Torvalds <torvalds@woody.linux-foundation.org>
> Date:   Thu Nov 15 08:44:36 2007 -0800
> 
>     Revert "skge: fix ram buffer size calculation"
>     
>     This reverts commit 7fb7ac241162dc51ec0f7644d4a97b2855213c32.
>     
>     Heikki Orsila reports that it causes a regression:
>     
>       "Doing
>     
>     	nc host port < /dev/zero
>     
>        on a sending machine (not skge) to an skge machine that is receiving:
>     
>     	nc -l -p port >/dev/null
>     
>        with ~60 MiB/s speed, causes the interface go malfunct. A slow
>        transfer doesn't cause a problem."
>     
>     See
>     
>     	http://bugzilla.kernel.org/show_bug.cgi?id=9321
>     
>     for some more information.
>     
>     There is a workaround (also reported by Heikki):
>     
>       "After some fiddling, I noticed that not changing the register write
>        order on patch:
>     
>        +       skge_write32(hw, RB_ADDR(q, RB_END), end);
>                skge_write32(hw, RB_ADDR(q, RB_WP), start);
>                skge_write32(hw, RB_ADDR(q, RB_RP), start);
>        -       skge_write32(hw, RB_ADDR(q, RB_END), end);
>     
>        fixes the visible effect..  Possibly not the root cause of the
>        problem, but changing the order back fixes networking here."
>     
>     but that has yet to be ack'ed or tested more widely, so the whole
>     problem-causing commit gets reverted until this is resolved properly.
>     
>     Bisected-and-requested-by: Heikki Orsila <shdl@zakalwe.fi>
>     Cc: Stephen Hemminger <shemminger@linux-foundation.org>
>     Cc: Jeff Garzik <jeff@garzik.org>
>     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> 
>  drivers/net/skge.c |   51 +++++++++++++++++++++++++++------------------------
>  1 files changed, 27 insertions(+), 24 deletions(-)

Thanks. I pulled

commit 8c0863403f109a43d7000b4646da4818220d501f

and now the skge driver works here.

-- 
Heikki Orsila			Barbie's law:
heikki.orsila@iki.fi		"Math is hard, let's go shopping!"
http://www.iki.fi/shd