From: Nicolas Schichan <nschichan@freebox•fr>
To: LKML <linux-kernel@vger•kernel.org>,
netdev@vger•kernel.org, linux-arm-kernel@lists•infradead.org
Cc: "David S. Miller" <davem@davemloft•net>,
Florian Fainelli <florian@openwrt•org>,
Leigh Brown <leigh@solinno•co.uk>,
Sebastian Hesselbarth <sebastian.hesselbarth@gmail•com>
Subject: Spurious timeouts in mvmdio
Date: Mon, 02 Dec 2013 16:15:54 +0100 [thread overview]
Message-ID: <529CA42A.3040504@freebox.fr> (raw)
Hi,
During 3.13-rc1 testing, I have found out that the mvmdio driver would report
timeouts on the kernel console:
[ 11.011334] orion-mdio orion-mdio: Timeout: SMI busy for too long
The hardware is a MV88F6281 Kirkwood CPU. The mvmdio driver is using the irq
line 46 (ge00_err).
I am inclined to believe that it is due to the fact that wait_event_timeout()
is called with a timeout parameter of 1 jiffy in orion_mdio_wait_ready(). If
the timer interrupt ticks right after calling wait_event_timeout(), we may end
up spending much less time than MVMDIO_SMI_TIMEOUT (1 msec) in
wait_event_timeout(), and as a result report a timeout as the MDIO access did
not complete in such a short time.
As to how to fix this, I see two options (I don't know which one would be
prefered):
- Option 1: always pass a timeout of at least 2 jiffy to wait_event_timeout().
- Option 2: switch to wait_event_hrtimeout().
I can provide patches for both options.
Regards,
--
Nicolas Schichan
next reply other threads:[~2013-12-02 15:15 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-02 15:15 Nicolas Schichan [this message]
2013-12-03 12:23 ` Spurious timeouts in mvmdio Jason Cooper
2013-12-03 12:40 ` Russell King - ARM Linux
2013-12-03 13:43 ` Jason Cooper
2013-12-03 18:48 ` Nicolas Schichan
2013-12-03 20:57 ` Leigh Brown
2013-12-03 22:45 ` Sebastian Hesselbarth
2013-12-03 23:20 ` Leigh Brown
2013-12-03 23:17 ` Sebastian Hesselbarth
2013-12-03 23:38 ` Leigh Brown
2013-12-03 23:42 ` Russell King - ARM Linux
2013-12-04 11:40 ` Nicolas Schichan
2013-12-16 18:07 ` Nicolas Schichan
2013-12-16 18:28 ` Leigh Brown
2013-12-17 13:49 ` Nicolas Schichan
2013-12-16 18:48 ` Russell King - ARM Linux
2013-12-03 23:45 ` Sebastian Hesselbarth
2013-12-03 13:16 ` [PATCH] net: mvmdio: fix wait_event_timeout() being called with a 1 jiffy timeout Nicolas Schichan
2013-12-03 13:34 ` Russell King - ARM Linux
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