linux-kernel - Re: [PATCH v2] net: mvmdio: fix interrupt timeout handling

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Message-ID: <aff941cf1be9b91cc58198b4c23a3e41@doppler.thel33t.co.uk>
Date:	Thu, 19 Dec 2013 19:35:01 +0000
From:	Leigh Brown <leigh@...inno.co.uk>
To:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Jason Cooper <jason@...edaemon.net>,
	Nicolas Schichan <nschichan@...ebox.fr>,
	netdev@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	Florian Fainelli <florian@...nwrt.org>,
	linux-arm-kernel@...ts.infradead.org,
	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
Subject: Re: [PATCH v2] net: mvmdio: fix interrupt timeout handling

On 2013-12-19 17:43, Jason Gunthorpe wrote:
> On Thu, Dec 19, 2013 at 01:09:48PM +0000, Leigh Brown wrote:
>> This version corrects the whitespace issue.
>> 
>> orion_mdio_wait_ready uses wait_event_timeout to wait for the
>> SMI interrupt to fire.  wait_event_timeout waits for between
>> "timeout - 1" and "timeout" jiffies.  In this case a 1ms timeout
>> when HZ is 1000 results in a wait of 0 to 1 jiffies, causing
>> premature timeouts.
>> 
>> This fix ensures a minimum timeout of 2 jiffies, ensuring
>> wait_event_timeout will always wait at least 1 jiffie.
>> 
>> Issue reported by Nicolas Schichan.
>> 
>> Tested-by: Nicolas Schichan <nschichan@...ebox.fr>
>> Signed-off-by: Leigh Brown <leigh@...inno.co.uk>
>>  drivers/net/ethernet/marvell/mvmdio.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
> 
> Leigh, I have just noticed a regression in 3.13-rc3 vs 3.10, on
> kirkwood where 3.13 occasionally prints:
> 
> 3 12/11 13:59:02 kernel: orion-mdio f1072004.mdio: Timeout: SMI busy
> for too long
> 
> Is that the same issue that this patch is addressing?

Yes, absolutely.

Regards,

Leigh.

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