Re: [PATCH 04/11] MFD: twl4030-audio: Add DT support

On 08/08/2012 05:49 PM, Mark Brown wrote:

That makes sense if the GPIO is actively driven, open drain should be
better here, but it's still a generic thing which it'd be nice to
extract.

Yes, the idea in it's core is generic, but right now I can not think of a
generic implementation which would work.
In case of twl4030 this is how it looks like:

1. if extmute is requested
 1.1. if GPIO number is not valid
   Use the internal MUTE functionality (HS_POPN_SET register, EXTMUTE bit)
 1.2. if GPIO number is valid
   set the GPIO to 1
2. Execute the sequence for the power up/down
3. if extmute is requested
 3.1. if GPIO number is not valid
   Use the internal MUTE functionality (HS_POPN_SET register, EXTMUTE bit)
 3.2. if GPIO number is valid
   set the GPIO to 0

For other devices it could be simpler:
1. Set GPIO for mute
2. Toggle a bit in the codec
3. Clear the GPIO to unmute

another device would need a sequence in step 2 instead of a single bit change.

To cover all of this in a generic way is not that straight forward IMHO.

Still, the main thing here was the fact that we should be able to drop
the flag for the feature in the first place.

Which flag you are referring?
I can (and have dropped) the hs_extmute_disable_level flag, but separate
hs_extmute, hs_extmute_gpio is needed for this device.

hs_extmute tells that the board implemented some sort of HS extmute functionality.
hs_extmute_gpio tells if the board is _not_ using the built in functionality,
but it is using external GPIO line to enable/disable the mute.

Sure I could do this:
hs_extmute: if only this is set we shall use the chip built in functionality
hs_extmute_gpio: if this is set we use the extmute feature but with external
                 GPIO.

But both need to be documented and supported.

-- 
Péter
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