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Date: Mon, 02 Dec 2013 16:15:54 +0100 From: Nicolas Schichan <nschichan@...ebox.fr> To: LKML <linux-kernel@...r.kernel.org>, netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org CC: "David S. Miller" <davem@...emloft.net>, Florian Fainelli <florian@...nwrt.org>, Leigh Brown <leigh@...inno.co.uk>, Sebastian Hesselbarth <sebastian.hesselbarth@...il.com> Subject: Spurious timeouts in mvmdio 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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