[alsa-devel] Driver for audio power amplifier ICs?

[Rick Mann]

> On Oct 1, 2015, at 02:04 , Lars-Peter Clausen <lars at metafoo.de> wrote:
> 
> On 10/01/2015 10:49 AM, Rick Mann wrote:
>> I've been working on this Beaglebone Black custom audio cape. It has a tlv320aic3104 codec (that I'm still trying to get working properly), and connected to its line outs is a tpa3140d2 analog 2x10W power amplifier. This chip has very little in the way of CPU interface, but it does have /shutdown and /fault lines.
>> 
>> I'm wondering how ALSA becomes aware of that chip, in order to enable it when it enables certain routes in the tlv320aic3104, and to inform application software if the /fault line asserts.
>> 
>> I don't mind writing a driver, if necessary, I just don't know where such a thing would fit. I also wonder what the device tree entries for the amp might look like.
> 
> Hi,
> 
> There are a couple of existing amplifier driver like e.g. max9877 or lm4857.
> While those two examples have I2C control interface it is no problem to
> implement a driver with just a GPIO control interface. Generally the input
> and output pins of the amplifier should be modeled as DAPM widgets with a
> widget for the amplifier function in between. You can use a callback
> function for the amplifier widget to get notified when the amplifier needs
> to be enabled and when not and can use this to control the GPIO.

Thanks, Lars, great! I'll take a look at those.

> The connections between the CODEC and the amplifier need to be specified in
> the board driver.

In this case I think that can all be done in the Device Tree, no?

-- 
Rick Mann
rmann at latencyzero.com