Re: [PATCH] ASoC: tas2562: Add support for digital volume control

[Dan Murphy]

Mark

On 2/20/20 1:40 PM, Mark Brown wrote:
> On Thu, Feb 20, 2020 at 01:22:34PM -0600, Dan Murphy wrote:
> > On 2/20/20 1:18 PM, Mark Brown wrote:
> > > decisions causing changes in the driver.  The system may have an
> > > external amplifier they prefer to use for hardware volume control, may
> > > prefer to do entirely soft volume control in their sound server or
> > > something like that.
> > But this is an amplifier.  Not sure why the system designer would design
> > cascading amplifiers.
> > And if that was the case wouldn't you want the output to be low so you don't
> > overdrive the ext amplifier front end?
> The point is that we don't know what people are doing and should try to
> keep the kernel out of policy decisions unless there's something that's
> clearly just unconditionaly right for all systems.  It's a lot easier to
> just have a clear rule that we defer to the wisdom of the silicon vendor
> than try to get into defaults, and it's a lot easier to just do this as
> consistently as we can rather than debating individual configuration
> changes.
I completely agree on keeping policy decisions out of the kernel.

> > I was considering safety in that the device is on at full blast (not sure
> > why the HW is defaulted that way but it is).
> I bet there's been issues with people turning things on and not
> realising they need register writes to hear anything, and the volume
> control here is a bit complex as well.
Ack
> > But if volume is adjusted prior to playback then this is not an issue.  But
> > if volume is not adjusted then it plays full blast.
> Wouldn't be the first time.  See all the dual purpose headphone/line
> outputs that people build, sensible defaults for headphones and line
> outputs are rather different.

OK.  I will remove them. Will do v3 tomorrow as v2 rearranged the values 
properly.  V3 will remove them.

Dan