On Wednesday 17 February 2010 09:29:37 Takashi Iwai wrote:
At Wed, 17 Feb 2010 08:16:32 -0500, Ed Tomlinson wrote:
On Tuesday 16 February 2010 08:37:46 Takashi Iwai wrote:
Thanks for the patch. It helps in that it eliminates the opps but lockdep still triggers and aplay still fails. Here is the new traceback.
Hmm, fixing this isn't so trivial. The same problem occurs on other subsystems like NFS over years. And it's still there, AFAIK. The mmap mutex appears suddenly in the strange code path at close.
The patch below might fix, but I'm not 100% sure whether this has no side effect.
Anyway, I doubt very much it being a regression. There is no change in ALSA core side, and also in V4L em28xx code. Maybe the lockdep wasn't triggered by some reason. And, this lockdep warning is almost harmless...
Takashi,
The second patch eliminating the lock causes oppes every time (one follows just in case its helpful).
Are you sure? The patch should causes a compile error, so you must have patched manually in a wrong place ;)
Yes I am sure. I fixed the compile error the same way it is fixed below.
Ed
Try the patch below (again untested, though).
thanks,
Takashi
diff --git a/drivers/media/video/em28xx/em28xx-audio.c b/drivers/media/video/em28xx/em28xx-audio.c index bd78338..c51e623 100644 --- a/drivers/media/video/em28xx/em28xx-audio.c +++ b/drivers/media/video/em28xx/em28xx-audio.c @@ -301,23 +301,12 @@ static int snd_em28xx_capture_open(struct snd_pcm_substream *substream) /* Sets volume, mute, etc */
dev->mute = 0;
mutex_lock(&dev->lock); ret = em28xx_audio_analog_set(dev);
mutex_unlock(&dev->lock); if (ret < 0) goto err;
runtime->hw = snd_em28xx_hw_capture;
if (dev->alt == 0 && dev->adev.users == 0) {
int errCode;dev->alt = 7;errCode = usb_set_interface(dev->udev, 0, 7);dprintk("changing alternate number to 7\n");}
mutex_lock(&dev->lock); dev->adev.users++;
mutex_unlock(&dev->lock);
snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS); dev->adev.capture_pcm_substream = substream;
@@ -336,7 +325,6 @@ static int snd_em28xx_pcm_close(struct snd_pcm_substream *substream) dprintk("closing device\n");
dev->mute = 1;
- mutex_lock(&dev->lock); dev->adev.users--; em28xx_audio_analog_set(dev); if (substream->runtime->dma_area) {
@@ -344,7 +332,6 @@ static int snd_em28xx_pcm_close(struct snd_pcm_substream *substream) vfree(substream->runtime->dma_area); substream->runtime->dma_area = NULL; }
mutex_unlock(&dev->lock);
return 0;
} @@ -352,6 +339,7 @@ static int snd_em28xx_pcm_close(struct snd_pcm_substream *substream) static int snd_em28xx_hw_capture_params(struct snd_pcm_substream *substream, struct snd_pcm_hw_params *hw_params) {
- struct em28xx *dev = snd_pcm_substream_chip(substream); unsigned int channels, rate, format; int ret;
@@ -366,6 +354,14 @@ static int snd_em28xx_hw_capture_params(struct snd_pcm_substream *substream, /* TODO: set up em28xx audio chip to deliver the correct audio format, current default is 48000hz multiplexed => 96000hz mono which shouldn't matter since analogue TV only supports mono */
- if (dev->alt == 0 && dev->adev.users == 1) {
int errCode;dev->alt = 7;errCode = usb_set_interface(dev->udev, 0, 7);dprintk("changing alternate number to 7\n");- }
- return 0;
}