From: boris.brezillon@free-electrons.com (Boris Brezillon)
To: linux-arm-kernel@lists.infradead.org
Subject: at91sam9 Main crystal frequency problems
Date: Tue, 6 Oct 2015 16:12:44 +0200 [thread overview]
Message-ID: <20151006161244.06f3ceb4@bbrezillon> (raw)
In-Reply-To: <55F6C07C.8080803@overkiz.com>
Hi Antoine,
On Mon, 14 Sep 2015 14:41:32 +0200
Antoine Aubert <a.aubert@overkiz.com> wrote:
> Hi Boris,
>
> Thank you for your help. I have some news thanks to traces in clk driver.
Any progress regarding this problem. I think Jiri (in Cc) has pretty
much the same problem (see this thread [1]).
IIRC, activating NO_HZ_IDLE solved the problem for you, but have you
find the root cause?
Best Regards,
Boris
[1]http://thread.gmane.org/gmane.linux.ports.arm.kernel/413356
>
>
> Le 08/09/2015 18:12, Boris Brezillon a ?crit :
> > Hi Antoine,
> >
> > On Mon, 7 Sep 2015 09:31:07 +0200
> > Antoine Aubert <a.aubert@overkiz.com> wrote:
> >
> >> Hi,
> >>
> >> I currently bring up a board based on AT91SAM9G25cu, and I having
> >> problems of watchdogs resets.
> >>
> >> We use linux-4.04 mainline, and i found some weird warnings on kernel
> >> traces, concerning main clk.
> >>
> >> [ 0.000000] Main crystal frequency not set, using approximate value
> >> [ 0.000000] master clk is overclocked
> >> [ 0.000000] sched_clock: 32 bits at 128 Hz, resolution 7812500ns,
> >> wraps every 16777216000000000ns
> >> [ 0.007812] Calibrating delay loop... 198.76 BogoMIPS (lpj=775168)
> >>
> >> I set crystal clock in the DT, but it doesn't seems to work.. I feel
> >> that the board works out of the specified range.
> >
> > According to your clk_summary dump that's not the case.
> >
> >>
> >> So here comes my questions:
> >> Can there be a relationship with watchdog problems ? (1 per day)
> >
> > I'd say no, but could you tell me more about your watchdog issues.
>
> Yet, we did not take the analysis. We just observed these resets.
>
> But, I found a clue:
> We recently removed the slow clock to the PCB. I forgot to disabled the
> slow_xtal. :/
> Can there be a link ? (I think so...)
>
> >
> >> Why is it that the frequency of Crystal is not found ?
> >
> > That's a good question, and honestly I don't. Everything seems to be
> > defined properly in your device tree.
> >
> > Could you add some traces in the fixed-rate clk driver [1] to see if the
> > main_xtal is correctly registered and if its registration occurs before
> > the main_osc registration?
>
> On our board, there is two kernel boot phases.
>
> First, we boot from at91-bootstrap.
> Second we launched kexec with an other kernel.
>
> I found that the device tree is well loaded from the at91-bootstrap. Any
> crystal issues. But, on kexec --exec, (with the same kernel) those
> issues appears. (see dmesg attached)
>
> If I launch kexec with --dtb, it's working ...
> I thought kexec keep old dtb. Was I wrong ?
>
> >
> > Best Regards,
> >
> > Boris
> >
> > [1]https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/tree/drivers/clk/clk-fixed-rate.c?id=refs/tags/v4.0.4#n115
> >
>
> Best regards,
> Antoine Aubert
> a.aubert at overkiz.com
--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
next prev parent reply other threads:[~2015-10-06 14:12 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-07 7:31 at91sam9 Main crystal frequency problems Antoine Aubert
2015-09-08 16:12 ` Boris Brezillon
2015-09-14 12:41 ` Antoine Aubert
2015-09-14 13:20 ` Boris Brezillon
2015-10-06 14:12 ` Boris Brezillon [this message]
2015-10-06 15:26 ` Antoine Aubert
2015-10-07 9:33 ` Sylvain Rochet
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20151006161244.06f3ceb4@bbrezillon \
--to=boris.brezillon@free-electrons.com \
--cc=linux-arm-kernel@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.