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

[Matthew Hagan]

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

> On Fri, Jun 25, 2021 at 11:52 AM Matthew Hagan <mnhagan88@xxxxxxxxx> wrote:
>> MX64 & MX64W Hardware info:
>>   - CPU: Broadcom BCM58625 Cortex A9 @ 1200Mhz
>>   - RAM: 2 GB (4 x 4Gb SK Hynix H5TC4G83CFR)
>>   - Storage: 1 GB (Micron MT29F8G08ABACA)
>>   - Networking: BCM58625 internal switch (5x 1GbE ports)
>>   - USB: 1x USB2.0
>>   - Serial: Internal header
>>   - WLAN(MX64W only): 2x Broadcom BCM43520KMLG on the PCI bus
>>
>> This patch adds the Meraki MX64 series-specific bindings. Since some
>> devices make use of the older A0 SoC, changes need to be made to
>> accommodate this case, including removal of coherency options and
>> modification to the secondary-boot-reg.
>>
>> Signed-off-by: Matthew Hagan <mnhagan88@xxxxxxxxx>
> Removing the dma-coherent flags in the dts file seemed really odd until
> I read the text above. It would seem more logical to me to have a .dtsi file
> that has all the a0 revision specific changes, and include that from the
> dts file.

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?

>
> 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?

>        Arnd
>
Matthew