audio hardlocks the machine

[mstone]

On 8.2.0-753, Pippy-25,

1. Start pippy and run the 'Bounce' example.

2. Swirl the mouse cursor in a circle. For me, initial swirls are smooth and become increasingly bumpy over a period of ~ 3-10 seconds until the cursor becomes unresponsive.

3. The screen is NOT redrawn, e.g. with a pygame window.

[mstone]

Seems that Pippy's 'Play sine' and cahalan's '/dev/audio' examples lock the machine in question even more quickly. So this may be dupe of #7885, or it may be a new hang.

cjb: does Bounce do any audio work?

[cjb]

No, bounce does no audio work. It uses pygame, though, so I can't guarantee that the audio device isn't mutated at all.

[thomaswamm]

I could not reproduce the Bounce bug with Pippy-25 in joyride-2301. There is no cursor displayed while "Hello!" bounces slowly around the screen.

[dsd]

I have Michael's laptop. Crash is entirely reproducible and also happens on update1 2.6.22 kernel. One line over serial console at time of crash:

[  148.708691] snd-malloc: invalid device type 0

[dsd]

The warning comes from snd_dma_free_pages, trace is:

[  164.510615]  [<c05652e7>] snd_cs5535audio_hw_free+0x42/0x59                  
[  164.511034]  [<c0556585>] snd_pcm_release_substream+0x32/0x63                
[  164.514740]  [<c05565f0>] snd_pcm_release+0x3a/0x81                          
[  164.521449]  [<c0459544>] __fput+0xab/0x17a                                  
[  164.525977]  [<c0448bb0>] remove_vma+0x34/0x45                               
[  164.534159]  [<c04498cc>] do_munmap+0x1ba/0x1d4                              
[  164.541571]  [<c0449915>] sys_munmap+0x2f/0x3d                               
[  164.546369]  [<c04037d2>] sysenter_past_esp+0x5f/0x85    

[dsd]

Tricky bug. It's not just bounce, its any audio producing application. Instant hard crash. It's unrelated to the above message, which is harmless.

[erikos]

Yeah absolutely reproducible with memorize in 2301. I had not that issue a few builds before - /versions/boot/alt/boot/olpc_build tells me the old build I used was 2273 so the devil must be in between.

[dsd]

Here's the trace:

SND_PCM_IOCTL_HWSYNC
snd_pcm_update_hw_ptr()
snd_pcm_update_hw_ptr_pos()
snd_cs5535audio_pcm_pointer()
cs5535audio_playback_read_dma_pntr()
cs_readl(cs5535au, ACC_BM0_PNTR)
<hang>

It hangs on inb(0x14e0). The port address is correct, I confirmed it on a machine that doesn't hang. Veery strange. Will save-nand and try 2273 now.

[dsd]

2273 exhibits the same problem on this laptop, as does 708!

[cjb]

Wow. Should we start reflashing older OFWs?

[dsd]

Q2D16 works. Seems like a Q2E regression.

[dsd]

Q2D16 works, Q2E10 fails.

[dsd]

This is because the volume in OpenFirmware was turned all the way down, causing OFW to not initialize the sound chip prior to linux boot. Mitch acknowledges that this is an OFW bug, he's working on a fix.

Workaround: during boot hit the "volume up" key a few times so that you can hear the boot jingle.

[wmb@…]

Fixed by svn 886 - OFW was leaving the AC97 registers disabled. The fix is to enable all of the virtualized PCI command registers before starting the OS.

The fix still needs to be rolled into an official OFW release.

[wmb@…]

The fix is in q2e14 .

[mstone]

Thanks for the prompt diagnosis and fix!