Re: OMAP1 realtime patch

Kevin Hilman
2007-02-12T19:24:30Z

On Sun, 2007-02-11 at 18:01 +0100, Dirk Behme wrote:
> Dirk Behme wrote:
> > Kevin Hilman wrote:
> >
> >> Here is a patch which leaves out the raw_spinlock conversions. It goes
> >> on the OMAP git tree on top of -rt5 (ignoring conflicts.) I've left out
> >> all the raw_spinlock conversions. This has been tested on an
> >> OMAP1623/H2 platform.
> >
> > Update of Kevins update. Tested on OSK.
> >
> > Changes:
> >
> > - Remove kernel/printk.c "+ zap_rt_locks();". It's already in -rt5.
> >
> > - Re-add HRTIMER conversion to ads7846.c
> >
> > With this patch I get Oops below after playing mp3 via NFS. Add
> > raw_spinlock_t to sound/arm/omap/omap-alsa-dma.c like in my original
> > patch doesn't seem to help.
>
> Re-adding raw_spinlock_t to omap-alsa.h helps against this Oops.

My guess the oops you sent is that you saw this crash when doing a
Ctrl-C or otherwise stopping the playback, correct?

This oops is triggered by the same thread trying to take the same
spinlock (now an rt_mutex under PREEMPT_RT.) The following patch
fixes the nested spinlocks, and removes the raw_spinlock. It applies
on top of your latest patch.

On my OSK, I do notice however that using -rt (with and without this
fix) mp3 playback has some audible noise under PREEMPT_RT. Do you hear
this too?

Kevin