From: Drew Fustini <dfustini@baylibre.com>
To: Tony Lindgren <tony@atomide.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>, Keerthy <j-keerthy@ti.com>,
linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Tero Kristo <kristo@kernel.org>, Suman Anna <s-anna@ti.com>
Subject: Re: [PATCH 2/2] clocksource/drivers/timer-ti-dm: Handle dra7 timer wrap errata i940
Date: Wed, 2 Feb 2022 12:54:59 -0800 [thread overview]
Message-ID: <Yfrvo+kVd9ZHJjBX@x1> (raw)
In-Reply-To: <Yfe25rpSY8OFPxzr@atomide.com>
On Mon, Jan 31, 2022 at 12:16:06PM +0200, Tony Lindgren wrote:
> Hi,
>
> * Drew Fustini <dfustini@baylibre.com> [220129 21:05]:
> > On Tue, Mar 23, 2021 at 09:43:26AM +0200, Tony Lindgren wrote:
> > > There is a timer wrap issue on dra7 for the ARM architected timer.
> > > In a typical clock configuration the timer fails to wrap after 388 days.
> > >
> > > To work around the issue, we need to use timer-ti-dm percpu timers instead.
> > >
> > > Let's configure dmtimer3 and 4 as percpu timers by default, and warn about
> > > the issue if the dtb is not configured properly.
> >
> > Hi Tony,
> >
> > This causes a conflict for IPU2 which is using timer 3 and 4.
> >
> > From arch/arm/boot/dts/dra7-ipu-dsp-common.dtsi:
> >
> > &ipu2 {
> > mboxes = <&mailbox6 &mbox_ipu2_ipc3x>;
> > ti,timers = <&timer3>;
> > ti,watchdog-timers = <&timer4>, <&timer9>;
> > };
>
> OK, sorry I missed that part.
>
> > I noticed an error ("could not get timer platform device") when booting
> > mainline on a BeagleBoard X15 (AM578):
> >
> > omap-rproc 55020000.ipu: assigned reserved memory node ipu2-memory@95800000
> > remoteproc remoteproc1: 55020000.ipu is available
> > remoteproc remoteproc1: powering up 55020000.ipu
> > remoteproc remoteproc1: Booting fw image dra7-ipu2-fw.xem4, size 3747220
> > omap-rproc 55020000.ipu: could not get timer platform device
> > omap-rproc 55020000.ipu: omap_rproc_enable_timers failed: -19
> > remoteproc remoteproc1: can't start rproc 55020000.ipu: -19
> >
> > I switched this errata fix to use timer 15 and 16 instead which resolves
> > the error. Do you think that is an acceptable solution?
>
> I think the only difference is that timers 15 and 16 are in l4_per3 instead
> of l4_per1. I doubt that matters as they are pretty much always clocked in
> this case. If you want to check you can run cyclictest :)
I ran this with existing errata fix with dmtimer 3 and 4:
root@am57xx-evm:~# cyclictest --mlockall --smp --priority=80 --interval=200 --distance=0
# /dev/cpu_dma_latency set to 0us
policy: fifo: loadavg: 0.02 0.03 0.05
T: 0 ( 1449) P:80 I:200 C: 800368 Min: 0 Act: 32 Avg: 22 Max: 128
T: 1 ( 1450) P:80 I:200 C: 800301 Min: 0 Act: 12 Avg: 23 Max: 70
And the results after my switch to dmtimer 15 and 16:
root@am57xx-evm:~# cyclictest --mlockall --smp --priority=80 --interval=200 --distance=0
# /dev/cpu_dma_latency set to 0us
policy: fifo: loadavg: 0.36 0.19 0.07
T: 0 ( 1711) P:80 I:200 C: 759599 Min: 0 Act: 6 Avg: 22 Max: 108
T: 1 ( 1712) P:80 I:200 C: 759539 Min: 0 Act: 19 Avg: 23 Max: 79
This doesn't appear to show any latency regression.
Any other options for cyclictest that that you'd recommend trying?
Thank you,
Drew
next prev parent reply other threads:[~2022-02-02 20:54 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-23 7:43 [PATCHv2 0/2] Fixes for for dra7 timer wrap errata i940 Tony Lindgren
2021-03-23 7:43 ` [PATCH 1/2] clocksource/drivers/timer-ti-dm: Prepare to handle dra7 timer wrap issue Tony Lindgren
2021-04-09 10:27 ` [tip: timers/core] " tip-bot2 for Tony Lindgren
2021-03-23 7:43 ` [PATCH 2/2] clocksource/drivers/timer-ti-dm: Handle dra7 timer wrap errata i940 Tony Lindgren
2021-04-09 10:27 ` [tip: timers/core] " tip-bot2 for Tony Lindgren
2022-01-29 21:05 ` [PATCH 2/2] " Drew Fustini
2022-01-31 10:16 ` Tony Lindgren
2022-02-02 20:54 ` Drew Fustini [this message]
-- strict thread matches above, loose matches on Subject: below --
2021-03-04 7:37 [PATCH 0/2] Fixes for for " Tony Lindgren
2021-03-04 7:37 ` [PATCH 2/2] clocksource/drivers/timer-ti-dm: Handle " Tony Lindgren
2021-03-22 10:15 ` Daniel Lezcano
2021-03-22 10:17 ` Tony Lindgren
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