On Sun, Dec 21, 2008 at 3:06 PM, Jarkko Nikula jhnikula@gmail.com wrote:

On Sun, Dec 21, 2008 at 9:22 AM, naveenkrishna. ch < naveenkrishna.ch@gmail.com> wrote:

...

Hi ALSA SOC,

I am using a OMAP3 + TWL4030 combination with ASoC

in the sound/soc/omap/omap-pcm.c DMA channels are being freed after unlinking in the omap_pcm_hw_free function

Which is causing a crash during applications So, stopping the DMA channels before unlinking resolves the issue.

here is the patch that solves the issue

diff --git a/sound/soc/omap/omap-pcm.c b/sound/soc/omap/omap-pcm.c index e9084fd..679e384 100644 --- a/sound/soc/omap/omap-pcm.c +++ b/sound/soc/omap/omap-pcm.c @@ -116,6 +116,7 @@ static int omap_pcm_hw_free(struct snd_pcm_substream *substream) if (prtd->dma_data == NULL) return 0;

•   omap_stop_dma(prtd->dma_ch);
   if (!cpu_is_omap1510())
           omap_dma_unlink_lch(prtd->dma_ch, prtd->dma_ch);
   omap_free_dma(prtd->dma_ch);
  
  
  

Is this ok or is there any better way out

This looks a bit familiar, I hope so. Is this from linux-omap, mainline or in-house kernel?

This is what i have seen in the alsa-kernel

There were similar issues fixed by following two patches in linux-omap. Second one is not yet in mainline, have to confirm with Tony has he queued it now.

commit 66c23551b1b774e2be3c7bdf91c0ebf2c7a3519e Author: Jarkko Nikula jarkko.nikula@nokia.com Date: Tue May 13 13:26:03 2008 +0300

ARM: OMAP: DMA: Don't mark channel active in omap_enable_channel_irq

Channel should be marked active only when DMA is really started.

Otherwise just omap_request_dma, omap_dma_link_lch and omap_dma_unlink_lch will cause incorrect dump_stack().

commit 55502f74b56f609a84d8919b9b29390b2e0147ff Author: Jarkko Nikula jarkko.nikula@nokia.com Date: Mon Aug 18 12:28:22 2008 +0300

ARM: OMAP: DMA: Fix uninitialized channel flags

This has similar symptoms than 66c23551b1b774e2be3c7bdf91c0ebf2c7a3519e
where just omap_request_dma, omap_dma_link_lch and omap_dma_unlink_lch
can cause incorrect dump_stack(). Here it can happen if channel has

been used before and the channel flags variable holds old status.

Signed-off-by: Jarkko Nikula <jarkko.nikula@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

Then it's worth to verify also this very recent fix. This is already in mainline and will flow into linux-omap when Tony does the pull.

commit 19b3f31609dc8be3a56c78dcb7da723f10f7009c Author: Stanley Miao stanley.miao@windriver.com Date: Fri Dec 19 22:08:22 2008 +0800

ALSA: Fix a Oops bug in omap soc driver.

There will be a Oops or frequent underrun messages when playing music

with omap soc driver, this is because a data region is incorretly sized, other da region will be overwriten when writing to this data region.

Jarkko