From: Benjamin Herrenschmidt <benh@kernel•crashing.org>
To: Segher Boessenkool <segher@kernel•crashing.org>
Cc: linuxppc-dev list <linuxppc-dev@ozlabs•org>,
Nathan Lynch <ntl@pobox•com>,
mcarlson@broadcom•com, Michael Chan <mchan@broadcom•com>,
netdev <netdev@vger•kernel.org>
Subject: Re: Strange tg3 regression with UMP fw. link reporting
Date: Fri, 08 Aug 2008 19:18:31 +1000 [thread overview]
Message-ID: <1218187111.24157.336.camel@pasglop> (raw)
In-Reply-To: <31233EB5-037E-4615-95C9-7C816E510752@kernel.crashing.org>
On Fri, 2008-08-08 at 10:58 +0200, Segher Boessenkool wrote:
> > I don't know yet for sure what happens, but a quick look at the commit
> > seems to show that the driver synchronously spin-waits for up to 2.5ms
>
> That's what the comment says, but the code says 2.5 _seconds_:
>
> + /* Wait for up to 2.5 milliseconds */
> + for (i = 0; i < 250000; i++) {
> + if (!(tr32(GRC_RX_CPU_EVENT) & GRC_RX_CPU_DRIVER_EVENT))
> + break;
> + udelay(10);
> + }
>
> (not that milliseconds wouldn't be bad already...)
Right, indeed. I think we have a good candidate for the problem :-) I'll
verify that on monday. Now, that leads to two questions:
- What such a synchronous and potentially horribly slow code is
going in a locked section or a timer interrupts ? Ie, the link
watch should probably move to a workqueue if that is to remain,
or the code turned into a state machine that periodically check for
events, or whatever is more sane than the above.
- The code should at least display some error and do something sane in
case of timeout such as disabling the new UMP feature instead of
repeatedly looping ...
- If this is indeed our problem (timing out in the code above), why is
our firmware not emitting the requested event -> maybe the PowerStations
need a tg3 firmware update.
Matt, what's your take on this ?
Cheers,
Ben.
next prev parent reply other threads:[~2008-08-08 9:18 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-08-08 7:35 Strange tg3 regression with UMP fw. link reporting Benjamin Herrenschmidt
2008-08-08 8:58 ` Segher Boessenkool
2008-08-08 9:18 ` Benjamin Herrenschmidt [this message]
2008-08-08 18:43 ` Matt Carlson
2008-08-08 15:20 ` Michael Chan
2008-08-08 22:05 ` Benjamin Herrenschmidt
2008-08-08 20:20 ` Michael Chan
2008-08-08 21:25 ` Nathan Lynch
2008-08-08 9:21 ` Arnd Bergmann
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