Re: [PATCH v6 00/10] Add support for RaspberryPi RP1 PCI device using a DT overlay

[Herve Codina <herve.codina@bootlin.com>]

Hi Phil,

On Thu, 13 Feb 2025 15:18:45 +0000
Phil Elwell <phil@raspberrypi.com> wrote:

> Hi Andrea,
> 
> The problem with this approach (loading an overlay from the RP1 PCIe
> driver), and it's one that I have raised with you offline, is that
> (unless anyone can prove otherwise) it becomes impossible to create a
> Pi 5 DTS file which makes use of the RP1's resources. How do you
> declare something as simple as a button wired to an RP1 GPIO, or fan
> connected to a PWM output?

The driver could be improved in a second step.
For instance, it could load the dtbo from user-space using request_firmare()
instead of loading the embedded dtbo.

> 
> If this is the preferred route to upstream adoption, I would prefer it
> if rp1.dtso could be split in two - an rp1.dtsi similar to what we
> have downstream, and an rp1.dtso that #includes it. In this way we can
> keep the patching and duplication to a minimum.

Indeed, having a rp1.dtsi avoid duplication but how the rp1.dtso in
the the kernel sources could include user customization (button, fan, ...)
without being modified ?
At least we have to '#include <my_rp1_customizations.dtsi>'.

Requesting the dtbo from user-space allows to let the user to create
its own dtso without the need to modify the one in kernel sources.

Does it make sense ?

Best regards,
Hervé