netdev - Re: am335x: cpsw: interrupt failure

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Date:	Mon, 29 Dec 2014 11:13:55 -0600
From:	Felipe Balbi <balbi@...com>
To:	Tony Lindgren <tony@...mide.com>
CC:	Felipe Balbi <balbi@...com>,
	Yegor Yefremov <yegorslists@...glemail.com>,
	netdev <netdev@...r.kernel.org>,
	"N, Mugunthan V" <mugunthanvnm@...com>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>
Subject: Re: am335x: cpsw: interrupt failure

On Mon, Dec 29, 2014 at 08:51:04AM -0800, Tony Lindgren wrote:
> * Felipe Balbi <balbi@...com> [141229 07:53]:
> > On Mon, Dec 29, 2014 at 10:33:26AM +0100, Yegor Yefremov wrote:
> > > On Fri, Dec 12, 2014 at 8:19 PM, Yegor Yefremov
> > > <yegorslists@...glemail.com> wrote:
> > > > On Fri, Dec 12, 2014 at 6:32 PM, Felipe Balbi <balbi@...com> wrote:
> > > >> Hi,
> > > >>
> > > >> On Fri, Dec 12, 2014 at 01:00:51PM +0100, Yegor Yefremov wrote:
> > > >>> U-Boot version: 2014.07
> > > >>> Kernel config is omap2plus with enabled USB
> > > >>>
> > > >>> # cat /proc/version
> > > >>> Linux version 3.18.0 (user@...r-VirtualBox) (gcc version 4.8.3
> > > >>> 20140320 (prerelease) (Sourcery CodeBench Lite 2014.05-29) ) #6 SMP
> > > >>> Mon Dec 8 22:47:43 CET 2014
> > > >>
> > > >> Wasn't GCC 4.8.x total crap for building ARM kernels ? IIRC it was even
> > > >> blacklisted. Can you try with 4.9.x just to make sure ?
> > > >
> > > > Will do.
> > > 
> > > Adding linux-omap. Beginning of this discussion:
> > > http://comments.gmane.org/gmane.linux.network/341427
> > > 
> > > Quick summary: starting with kernel 3.18 or commit
> > > 55601c9f24670ba926ebdd4d712ac3b177232330 am335x (at least BBB and some
> > > custom boards) stalls at high network load. Reproducible via nuttcp
> > > within some minutes
> > > 
> > > nuttcp -S (on BBB)
> > > nuttcp -t -N 4 -T30m 192.168.1.235 (on host)
> > > 
> > > As Felipe Balbi suggested, I tried both 4.8.3 and 4.9.2 toolchains,
> > > but both show the same behavior.
> > > 
> > > Linux version 3.18.0 (user@...r-VirtualBox) (gcc version 4.8.3
> > > 20140320 (prerelease) (Sourcery CodeBench Lite 2014.05-29) ) #6 SMP
> > > Mon Dec 8 22:47:43 CET 2014
> > > Linux version 3.18.1 (user@...r-VirtualBox) (gcc version 4.9.2
> > > (Buildroot 2015.02-git-00582-g10b9761) ) #1 SMP Mon Dec 29 09:22:29
> > > CET 2014
> > > 
> > > Let me know, if you can reproduce this issue.
> > 
> > finally managed to reproduce this, it took quite a bit of effort though.
> > I'll see if I can gether more information about the problem.
> 
> Maybe check if the irqnr is 127 (or the last reserved interrupt)
> in irq-omap-intc.c. If so, also print out the previous interrupt.
> It seems the intc uses the last reserved interrupt to signal a
> spurious interrupt for the previous irqnr, so we should probably
> add some handling for that.
> 
> If the previous interrupt is a cpsw interrupt, then there's probably
> something wrong with cpsw interrupt handling. Either a missing
> read-back to flush posted write in the cpsw interrupt handler,
> or the EOI registers are written at a wrong time.

yeah, I'll go over it, but I first need to reproduce it again. Just
rebooted to try again and after half an hour, couldn't reproduce it
anymore. Interesting race to end the year :-)

cheers

-- 
balbi

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