At Mon, 09 Mar 2009 10:32:02 +0200, Timo T.Hyrsylä wrote:

Trying to make Alsa work on our embedded arm system with ixdp425 and CS4281.

kernel is 2.6.20.3 and the Alsas (driver+lib+utils) latest 1.0.19

Other than the two below errors, the system seems to work ok.

When removing the snd_cs4281 module, dmesg reports multiple errors about bad page

<0>Bad page state in process 'rmmod' <0>page:c4007300 flags:0x00004000 mapping:00000000 mapcount:0 count:0 <0>Trying to fix it up, but a reboot is needed <0>Backtrace: <0>Bad page state in process 'rmmod' <0>page:c4007320 flags:0x00004000 mapping:00000000 mapcount:0 count:0 <0>Trying to fix it up, but a reboot is needed <0>Backtrace:

I've managed to track down the error upto dma_free_coherent.

snd_pcm_free > snd_pcm_lib_preallocate_free_for_all > snd_pcm_lib_preallocate_free > snd_pcm_lib_preallocate_dma_free > snd_dma_free_pages > snd_free_dev_pages > dma_free_coherent

Another issue, possibly related, is that when running aplay with --mmap it will crash with:

Internal error: Oops: f3 [#1] PC is at snd_pcm_mmap_data_nopage+0x10c/0x148 [snd_pcm] LR is at __handle_mm_fault+0x16c/0x8ac

This is likely the problem with dma_alloc_coherent() and mmap on a non-coherent architecture. I have patches for these, but only for recent kernels. The patches are found in test/dma-fix branch of sound git tree: git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6.git test/dma-fix

Takashi