Re: [Xenomai] Xenomai on Atmel SAMA5D3 with a 3.14 kernel

[Maxime Ripard <maxime.ripard@free-electrons.com>]

On Tue, Jun 10, 2014 at 11:48:25AM +0200, Gilles Chanteperdrix wrote:
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> On 06/10/2014 11:40 AM, Maxime Ripard wrote:
> > On Sat, Jun 07, 2014 at 04:34:34PM +0200, Gilles Chanteperdrix
> > wrote:
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> >> On 06/06/2014 04:00 PM, Maxime Ripard wrote:
> >>> On Fri, Jun 06, 2014 at 03:59:12PM +0200, Maxime Ripard wrote:
> >>>> Hi Gilles,
> >>>> 
> >>>> I've been experimenting these days with the i-pipe 3.14
> >>>> kernel, and current xenomai master branch on the Atmel
> >>>> SAMA5D3 SoC.
> >>>> 
> >>>> There's a few issues there, the first one being that 
> >>>> at91_ipipe_early_init crashes because of a NULL pointer 
> >>>> dereference. This is due to the clk_get_rate call on the
> >>>> clock returned by clk_get(NULL, "mck").
> >>>> 
> >>>> This clk_get call cannot since 3.14 because the clock code
> >>>> has been rewritten, and you can't use clkdev anymore.
> >>>> 
> >>>> This is quite simple to fix, and after actually fixing it,
> >>>> you get a more interesting issue: either the timers or the 
> >>>> interrupts don't work at all.
> >>>> 
> >>>> The first symptom is that it get stuck at the delay loop 
> >>>> calibration. Setting the loops per jiffy in the command line 
> >>>> make the boot go further, until the switch to the ipipe_tsc 
> >>>> clocksource. This actually makes me think that it's more the
> >>>>  timers that are broken rather than the interrupts. Changing
> >>>> the timer counter block doesn't solve anything.
> >>>> 
> >>>> Do you have an idea of what could be going on?
> >>> 
> >>> 
> >>> Actually, the boot seem just to be *much* slower, so maybe the
> >>>  timers are working after all, but it's just yet another issue
> >>> with the clocks.
> >>> 
> >> Does __ipipe_tsc_update get called in Linux timer interrupt?
> > 
> > Here is what's happening: http://pastebin.com/m2mz66pU
> > 
> > You can see that at line 35, the timer interrupt (a spurious one?) 
> > gets called, and calls __ipipe_tsc_update. At that point, 
> > ipipe_tsc_value seems to be NULL, and hence __ipipe_tsc_update 
> > returns.
> > 
> > The thing is, the timer interrupt doesn't seem to be called again.
> > The fact that it was actually called once makes me think that it's
> > rather the timer clock that is not running... I will dig into it.
> 
> If you have CONFIG_NO_HZ enabled, try to turn it off.

CONFIG_NO_HZ is disabled, here is the full config:
http://pastebin.com/fmVGTX4W

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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