From: Arnd Bergmann <arnd@arndb•de>
To: Benjamin Herrenschmidt <benh@kernel•crashing.org>
Cc: akpm@osdl•org, netdev@vger•kernel.org,
James K Lewis <jklewis@us•ibm.com>,
linux-kernel@vger•kernel.org, linuxppc-dev@ozlabs•org,
ens Osterkamp <Jens.Osterkamp@de•ibm.com>,
Jeff Garzik <jgarzik@pobox•com>
Subject: Re: [PATCH 2/6]: powerpc/cell spidernet low watermark patch.
Date: Sun, 20 Aug 2006 12:03:14 +0200 [thread overview]
Message-ID: <200608201203.15645.arnd@arndb.de> (raw)
In-Reply-To: <1156055509.5803.77.camel@localhost.localdomain>
On Sunday 20 August 2006 08:31, Benjamin Herrenschmidt wrote:
> > card->low_watermark->next->dmac_cmd_status |= SPIDER_NET_DESCR_TXDESFLG;
> > mb();
> > card->low_watermark->dmac_cmd_status &= ~SPIDER_NET_DESCR_TXDESFLG;
> > card->low_watermark = card->low_watermark->next;
> >
> > when we queue another frame for TX.
>
> I would have expected those to be racy vs. the hardware... what if the
> hardware is updating dmac_cmd_status just as your are trying to and the
> bit out of it ?
Right, that doesn't work. It is the only bit we use in that byte though,
so maybe it can be done with a single byte write.
Arnd <><
next prev parent reply other threads:[~2006-08-20 10:03 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-18 22:07 [PATCH 0/6]: powerpc/cell spidernet ethernet driver update Linas Vepstas
2006-08-18 22:20 ` [PATCH 1/6]: powerpc/cell spidernet burst alignment patch Linas Vepstas
2006-08-18 22:51 ` Arnd Bergmann
2006-08-18 22:21 ` [PATCH 2/6]: powerpc/cell spidernet low watermark patch Linas Vepstas
2006-08-18 23:09 ` Arnd Bergmann
2006-08-20 6:31 ` Benjamin Herrenschmidt
2006-08-20 10:03 ` Arnd Bergmann [this message]
2006-08-23 21:36 ` Linas Vepstas
2006-08-23 22:03 ` David Miller
2006-08-18 22:23 ` [PATCH 3/6]: powerpc/cell spidernet stop error printing patch Linas Vepstas
2006-08-18 22:25 ` [PATCH 4/6]: powerpc/cell spidernet ethtool -i version number info Linas Vepstas
2006-08-18 22:56 ` Arnd Bergmann
2006-08-18 22:26 ` [PATCH 5/6]: powerpc/cell spidernet bottom half Linas Vepstas
2006-08-18 23:03 ` Arnd Bergmann
2006-08-19 0:56 ` [RFC] HOWTO use NAPI to reduce TX interrupts Arnd Bergmann
2006-08-20 1:31 ` Stephen Hemminger
2006-08-19 11:25 ` Arnd Bergmann
2006-08-20 17:48 ` [RFC v2] " Arnd Bergmann
2006-08-21 20:40 ` NAPI documentation Stephen Hemminger
2006-08-21 22:05 ` David Miller
2006-08-21 22:09 ` Stephen Hemminger
2006-08-21 22:17 ` David Miller
2006-08-21 23:52 ` [RFC] HOWTO use NAPI to reduce TX interrupts Linas Vepstas
2006-08-21 23:56 ` David Miller
2006-08-22 0:29 ` Roland Dreier
2006-08-22 0:32 ` David Miller
2006-08-23 1:29 ` Shirley Ma
2006-08-23 21:52 ` [PATCH 5/6]: powerpc/cell spidernet bottom half Linas Vepstas
2006-08-18 22:29 ` [PATCH 6/6]: powerpc/cell spidernet refine locking Linas Vepstas
-- strict thread matches above, loose matches on Subject: below --
2006-09-29 23:05 [PATCH 0/6]: powerpc/cell spidernet ethernet patches Linas Vepstas
2006-09-29 23:17 ` [PATCH 2/6]: powerpc/cell spidernet low watermark patch Linas Vepstas
2006-09-30 10:30 ` Arnd Bergmann
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