[alsa-devel] [PATCH 3/3] imx-ssi: Use a hrtimer in FIQ mode

Valentin Longchamp valentin.longchamp at epfl.ch
Thu Apr 8 17:29:29 CEST 2010

Sascha Hauer wrote:
> Using a regular timer results in poll times < 1 jiffie with small
> buffers, so we loaded the timer with the actual jiffie value. We can
> be more accurate using a hrtimer. Also, we have to call
> snd_pcm_period_elapsed after playing period_bytes and not
> runtime->period_size (which is in samples and not in bytes).
> Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
> ---
>  sound/soc/imx/imx-pcm-fiq.c |   45 ++++++++++++++++++++----------------------
>  1 files changed, 21 insertions(+), 24 deletions(-)

Sorry to bother you guys in your discussion (most of which I don't 
understand because of my poor alsa knowledge).

I just wanted to tell that I have given this patch a spin on a 
mx31moboard system. imx-ssi now works much better (the audio does not 
loop on one buffer anymore as it did with the earlier timer version) in 
various configuration (speaker-test with various rates up to 48 kHz as 
well as aplay with a wav file, which had never worked for me) and the 
CPU usage is much lower BUT I have experienced some deadlocks completely 
hanging the system looping on what should be the last buffer of the wave 


Valentin Longchamp, PhD Student, EPFL-STI-LSRO1
valentin.longchamp at epfl.ch, Phone: +41216937827
MEB3494, Station 9, CH-1015 Lausanne

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