[alsa-devel] [PATCH 1/1] ASoC: TWL4030: Headset VMID ramp fix

[Mark Brown]

On Fri, May 08, 2009 at 02:56:50PM +0300, Peter Ujfalusi wrote:

> Realistically we can not add 2581ms delay to the headsetl_event function...
> We could keep the VMID enabled all the time (which increases the idle power 
> consumption by ~0.001A), but then the muting of the headset 

Generally you want to leave VMID up all the time for exactly this reason
- ramping it cleanly with that generation of hardware just takes too
long to do it regularly during normal operation.

> (HS_POP_GAIN:HSL_GAIN, HSR_GAIN = 0) will give the 'tuck'...

Have you tried ramping the gain down gradually?  DAPM can do that for you
automatically if the volume control is attached to the PGA.

> In power consumption the difference between
> HS_POP_GAIN:HSL_GAIN, HSR_GAIN == 0 and
> HS_POP_GAIN:HSL_GAIN, HSR_GAIN != 0 is about ~0.01A, which is significant in 
> my opinion.

Yup, that's definitely going to be noticable.

> Using a timer to finish the ramp down?

How well does the device cope with aborting the ramp down?  If it can
handle it then that seems like a reasonable approach.  Othwerise it's
sounding like you may have to give people the option of either living
the pop or having the very slow ramp.