[Letux-kernel] OMAP5+TWL6040: CONFIG_CPU_IDLE=y breaks (non AESS) audio

Tony Lindgren tony at atomide.com
Tue Nov 6 16:47:30 CET 2018


* H. Nikolaus Schaller <hns at goldelico.com> [181029 18:12]:
> So we face this situation:
> * CONFIG_CPU_IDLE=y reduces idle current of OMAP3 by 10mA (important for power saving! also for Pyra)
> * CONFIG_CPU_IDLE=y breaks audio on OMAP5 + twl6040 (but not on Pandaboard ES OMAP4 + twl6040)
> 
> What fix is needed to make mainline (does not include AESS) OMAP5+TWL6040 work
> in combination with CONFIG_CPU_IDLE=y?

The audio components do not block deeper idle states in the
hardware. So the driver needs to use PM QoS to prevent glitches,
see for example what was done in commit 9834ffd1ecc3 ("ASoC:
omap-mcbsp: Add PM QoS support for McBSP to prevent glitches").

I guess you need to do it for mcpdm in this case?

Regards,

Tony


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