Re: [PATCH 2/5] dt-bindings: arm: ti: Add compatible for AM625-based TQMa62xx SOM family and carrier board

[Rob Herring <robh@kernel.org>]

On Mon, Nov 11, 2024 at 10:58:57AM +0100, Matthias Schiffer wrote:
> On Wed, 2024-11-06 at 16:40 +0000, Conor Dooley wrote:
> > On Wed, Nov 06, 2024 at 01:03:08PM +0100, Matthias Schiffer wrote:
> > > On Tue, 2024-11-05 at 18:55 +0000, Conor Dooley wrote:
> > > > On Tue, Nov 05, 2024 at 11:40:20AM +0100, Matthias Schiffer wrote:
> > > > > On Mon, 2024-11-04 at 18:47 +0000, Conor Dooley wrote:
> > > > > > On Mon, Nov 04, 2024 at 10:47:25AM +0100, Matthias Schiffer wrote:
> > > > > > > The TQMa62xx is a SoM family with a pluggable connector. The MBa62xx is
> > > > > > > the matching reference/starterkit carrier board.
> > > > > > 
> > > > > > Why all the wildcards? Why isn't there a compatible per device in the
> > > > > > family?
> > > 
> > > Because all variants use the same Device Tree. There is also only one compatible and one (main) DTSI
> > > for the AM62 SoC family, which our Device Trees are based on.
> > 
> > So what varies between the members of the family?
> 
> There are currently 6 SoCs in the family:
> - AM6254
> - AM6252
> - AM6251
> - AM6234
> - AM6232
> - AM6231
> 
> They differ in:
> - Existence of GPU (AM625 vs AM623)
> - Number of Cortex-A53 cores (last digit)
>  
> All of these use ti,am625 as their SoC-level compatible. The differences are currently handled by U-
> Boot, which checks various feature flags in the SoC registers and patches the OS DTB accordingly by
> removing CPU nodes and disabling the GPU node if necessary.

That's how it should be. Most likely, those are all the same die. 
Different die are expensive and it takes a high volume to justify the 
cost.

Rob