Re: [PATCH v4 2/4] ARM: dts: NSP: Add DT files for Meraki MX64 series

On Fri, Jun 25, 2021 at 7:30 PM Florian Fainelli [off-list ref] wrote:

On 6/25/21 10:26 AM, Matthew Hagan wrote:

quoted

On 25/06/2021 10:59, Arnd Bergmann wrote:

How about having separate bcm-nsp-ax and bcm-nsp-bx dtsi files with the
appropriate secondary-boot-reg and dma-coherent (or lack of)
properties, which then include bcm-nsp.dtsi. Thus we can also avoid use
of /delete-property/. Would this be preferable?

That sounds good to me.

Is there any way that the Ax platforms could use a small shim between
the boot loader and the kernel which could all of the necessary DT
adaptation so the kernel only contains a single Device Tree source?

Using something like this:

https://github.com/zonque/pxa-impedance-matcher/

could be useful.

I don't think that's necessary here, but I wouldn't object if someone
finds it useful and does the work. ;-)

quoted

quoted

On the other hand, the /chosen, /aliases and  /memory nodes that you have
in the .dtsi file should probably get moved into the .dts files, as these tend
to be board specific settings, even if the examples you have are all
the same.

I did not come across any convention regarding this, though there are
plenty of cases where the /chosen, /aliases and /memory nodes are
defined in a .dtsi file and used by multiple similar boards. Also note
in this case /aliases is defined in bcm-nsp.dtsi, not by me. Would we
not prefer to avoid having 6x duplication?

We are not too consistent about this, and there are cases in which a
.dtsi file is used for a family of boards using different SoCs rather than
a particular SoC or SoC family.

In the bcm-nsp.dtsi example you mention, I would move the aliases into
the board files, mainly because there is no guarantee that each board
exposes both uarts and all three on-chip ethernet ports. Note that the
aliases are supposed to match whatever label you have on the board,
not what the numbers are in the chip.

      Arnd