Re: [PATCH] ASoC: dapm: add kcontrol to switch regulator to regulated/bypass state

[Nikesh <noswal@opensource.wolfsonmicro.com>]

Hi Mark,

Thanks for your response. The problem we had is the dapm is holding an 
instance of the regulator and we wanted to control that instance based 
on use-case. But I understand your point that we should not be exposing 
regulators to userspace but manage it in the driver itself..will have a 
re-think

Thanks,
Nikesh

On 08/09/15 14:22, Mark Brown wrote:
> On Tue, Sep 08, 2015 at 11:14:09AM +0100, Nikesh Oswal wrote:
>> When regulator is defined with SND_SOC_DAPM_REGULATOR_CONTROL_BYPASS
>> flag, then a kcontrol will be created which can be used to switch
>> regulator to regulated/bypass state. This will help to control the
>> behaviour of the regulator based on a usecase. For example voice call
>> may need a regulated voltage to acheive higher quality whereas voice
>> trigger may need bypass voltage so as to save on power.
> This is really not a good idea, moving a regulator from regulated to
> bypass without coordination with the driver is a recipie for bugs at
> best and physical damage at worst.  It's something that should be being
> done by the device driver based on the current state of the device, the
> general model is that we always drive to the lowest power state possible
> based on what the device is currently doing.  If the device is set up to
> do something that can use an unregulated supply then it should put the
> supply into bypass mode without any help from userspace.
>
> As I think we went through the last time you submitted code to the core
> it is very important that we have coherent and safe abstractions that
> result in code which does what it says.  The code in the core has to
> work coherently for everyone, just randomly punching holes through
> abstractions for system specific hacks from userspace is not going to do
> that.