Re: [PATCH 3/3] arm64: dts: broadcom: bcm2712: Add the otp nodes to firmware

Gregor Herburger
2026-04-09T12:02:46Z

Hi Krzysztof,

thanks for reviewing.

On Thu, Apr 09, 2026 at 10:15:12AM +0200, Krzysztof Kozlowski wrote:
> On Wed, Apr 08, 2026 at 10:00:17AM +0200, Gregor Herburger wrote:
> > The Raspberry Pi 5 has two OTP registers (private and customer), add these
> > to the devicetree.
>
> So this sentence confirms my question on bindings - your device
> raspberrypi,bcm2835-firmware has these, thus you do not need these child
> nodes at all. Neither compatibles.

I dont't think so. In my understanding the bcm2835-firmware does not
provide the otp registers but only provides the interface to the
registers. Though I don't know the details how this is done but [1] says
that only BCM2712 has 512bits and the others (like bcm2711) have
256bits. So both devicetrees have the raspberrypi,bcm2835-firmware node
but only the bcm2712 has the raspberrypi,firmware-otp-private node while the
raspberrypi,firmware-otp-customer is available in all raspberrys.

> Drop entire DTS and binding patches.

If I drop the binding patch how to distinguish the variants? Should I
add a SoC specific compatible? e.g. `raspberrypi,bcm2712-firmware` and
use it in the firmware/raspberrypi driver to add the second otp region?

Also what I don't understand why we have all the bindings for
'raspberrypi,firmware-clocks', 'raspberrypi,firmware-gpio',
'raspberrypi,firmware-reset', 'raspberrypi,firmware-poe-pwm' and
'raspberrypi,firmware-ts'. What is the difference between these devices
and the otp registers. They are all accessed through the firmware.

[1] https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#device-specific-private-key

Best regards
Gregor