Re: TK1 System Freeze

[Tuomas Tynkkynen <tuomas-yrGDUoBaLx3QT0dZR+AlfA@public.gmane.org>]

Hi Stefan,

On Tue, 06 Feb 2018 08:51:19 +0100
stefan-XLVq0VzYD2Y-XMD5yJDbdMReXY1tMh2IBg@public.gmane.org wrote:

> On 13.01.2018 01:19, Stefan Agner wrote:
> > Hi Marcel, Hi Thierry,
> > 
> > On 2017-11-20 00:57, Marcel Ziswiler wrote:  
> >> Hi there
> >>
> >> I lately was tasked to run some legacy Qt4e [1] application on Apalis
> >> TK1. It should really only draw directly to the Linux frame buffer
> >> /dev/fb0. Strangely as soon as that application is started the whole
> >> system freezes. Running it with the VNC backend or a pure frame buffer
> >> emulation it works just fine. So it must have something to do with the
> >> particular way the frame buffer is done on TK1. So far no attempt in
> >> debugging this any further bear any fruit. Whether stracing what the
> >> application is doing nor tracing the linux kernel side of things
> >> revealed where exactly the freeze happens. As I feared some kind of a
> >> configuration issue on Apalis TK1 I also tried the same on Jetson TK1
> >> with latest stock Linux kernel 4.14. However the same freeze happens.  
> > 
> > This is still the case with 4.15-rc7.
> > 
> > While dd is not enough to reproduce it, using a simple fbdev application
> > such as ts_calibrate seems to be sufficient. Qt and ts_calibrate use
> > mmap for the framebuffer. The system seems to freeze when it tries to
> > write into the mapped area (at the memset line):
> > https://github.com/kergoth/tslib/blob/master/tests/fbutils-linux.c#L160
> > 
> > Is this a known problem? Any idea?  
> 
> Thierry, anybody else, any idea? This should be easily reproducible on
> Jetson TK1.
> 

Some time ago I was able to cause a similar-sounding hang by running kmscon[1]
on the Jetson TK1. I remember that I tried the debug the problem with a
Lauterbach JTAG debugger at some point, but whatever steps that I did
to make the Lauterbach usable on mainline also made the problem disappear!
IIRC, it was disabling cpuidle (either via cmdline or sysfs, can't remember)
that made the hang go away.

[1]: https://github.com/dvdhrm/kmscon

- Tuomas