[PATCH 6/7] ARM: dts: Add dts for Raspberry Pi 4 + Cirrus Logic Lochnagar2

Richard Fitzgerald rf at opensource.cirrus.com
Fri Oct 16 05:01:46 EDT 2020

On 15/10/2020 16:12, Nicolas Saenz Julienne wrote:
> On Thu, 2020-10-15 at 12:14 +0100, Richard Fitzgerald wrote:
>>> Sadly I don't think creating a new device tree is a good solution here. If we
>>> were to do so for every RPi hat/usage it'd become unmanageable very fast. There
>>> is a way to maintain this in the open nonetheless. I suggest you build a DT
>>> overlay and submit it to https://github.com/raspberrypi/linux, see
>>> 'arch/arm/boot/dts/overlays.' The Raspberry Pi engineers have a kernel branch
>> We want something in mainline so that it can be used by people
>> developing on mainline and taken as a starting point for configuring
>> the codecs for other host platforms. The RPi is a convenient platform to
>> use as the base because it is widely available and low-cost.
> If what you want to convey is the proper way of configuring your specific
> device the way to go is writing a devicetree binding. See

If we have a working configuration it is unreasonable not to make this
available for people who want to use it or examine it. A working example
can be more helpful than a ton of documentation.

It's also worth noting that setting up a working sound system involves
configuring multiple drivers (for example you also need a properly
configured ASoC machine driver at least) crossing multiple driver
bindings. So a complete working example is valuable to see how
it fits together.

> Documentation/devicetree. It's even possible to validate a given devicetree
> against the bindings (given they are written in yaml format).

Validating only checks syntax and bounds. It doesn't prove that it will

> Regards,
> Nicolas

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