On 06/03/2013 08:51 PM, Mark Brown wrote:
On Mon, Jun 03, 2013 at 11:36:40AM -0600, Stephen Warren wrote:
From: Stephen Warren swarren@nvidia.com
Currently, when the system enters suspend with audio playing, since the DAI widgets are active, the associated CODEC is considered active, and hence is not transition into a low-power bias state as the system suspends. This likely causes audio failure after resume, since the CODEC power has quite possibly been removed during suspend, and the bias level transitions in the CODEC driver are needed to recover from this. At the very least, this issue likely causes warnings in the kernel log due to the CODEC being left on over the suspend transition.
To solve this, modify dapm_dai_check_power() not to consider DAI widgets active if the system is entering suspend.
I would expect us to be dealing with this as part of quiescing the DMA operations on the links - it's not just the CODEC that needs handling here. This feels like it ought to be more joined up somewhere along the line.
I think it is just an oversight that this is not working properly right now. In snd_soc_suspend() where we also stop the DMA streams etc the DAI link widgets are put into suspend, by calling snd_soc_dapm_stream_event(..., SND_SOC_DAPM_STREAM_SUSPEND). But dapm_dai_check_power() doesn't consider this and hence stays active and also keeps the whole DAPM context (this is not CODEC specific) active.
- Lars