Hi Takashi Iwai, Jaroslav Kysela
We encountered an issue in the pcm_dsnoop use case, could you please
help to have a look?
*Issue description:*
With two instances for dsnoop type device running in parallel, after
suspend/resume, one of the instances will be hung in memcpy because the
very large copy size is obtained.
#3 0x0000ffffa78d5098 in snd_pcm_dsnoop_sync_ptr (pcm=0xaaab06563da0)
at pcm_dsnoop.c:158
dsnoop = 0xaaab06563c20
slave_hw_ptr = 64
old_slave_hw_ptr = 533120
avail = *187651522444320*
* Reason analysis: *
The root cause that I analysis is that after suspend/resume, one
instance will get the SND_PCM_STATE_SUSPENDED state from slave pcm device,
then it will do snd_pcm_prepare() and snd_pcm_start(), which will reset
the dsnoop->slave_hw_ptr and the hw_ptr of slave pcm device, then the
state of this instance is correct. But another instance may not get
the SND_PCM_STATE_SUSPENDED state from slave pcm device because slave
device may have been recovered by first instance, so
the dsnoop->slave_hw_ptr is not reset. but because hw_ptr of slave pcm
device has been reset, so there will be a very large "avail" size.
*Solution:*
I didn't come up with a fix for this issue, seems there is no easy way
to let another instance know this case and reset the
dsnoop->slave_hw_ptr, could you please help?
Best regards
Wang shengjiu
