On Mon, Feb 10, 2025 at 03:53:24PM -0600, Rob Herring wrote:

On Sun, Feb 09, 2025 at 02:31:34PM -0600, Crystal Wood wrote:

quoted

On Fri, Feb 07, 2025 at 10:30:26PM +0100, J. Neuschäfer via B4 Relay wrote:

quoted

From: "J. Neuschäfer" <redacted>

Convert the Freescale localbus controller bindings from text form to
YAML. The updated list of compatible strings reflects current usage
in arch/powerpc/boot/dts/, except that many existing device trees
erroneously specify "simple-bus" in addition to fsl,*elbc.

Changes compared to the txt version:
 - removed the board-control (fsl,mpc8272ads-bcsr) node because it only
   appears in this example and nowhere else
 - added a new example with NAND flash
 - updated list of compatible strings

Signed-off-by: J. Neuschäfer <redacted>
---

V2:
- fix order of properties in examples, according to dts coding style
- move to Documentation/devicetree/bindings/memory-controllers
- clarify the commit message a tiny bit
- remove unnecessary multiline markers (|)
- define address format in patternProperties
- trim subject line (remove "binding")
- remove use of "simple-bus", because it's technically incorrect

While I admit I haven't been following recent developments in this area,
as someone who was involved when "simple-bus" was created (and was on the
ePAPR committee that standardized it) I'm surprised to hear simple-bus
being called "erroneous" or "technically incorrect" here.

Erroneous because the binding did not say "simple-bus" was used. Not 
uncommon with the old .txt bindings.

Generally, if a bus has control registers or resources like clocks, then 
we tend not to call them 'simple-bus'. And '"specific-bus", 
"simple-bus"' gives some problems around what driver if any do you 
bind to. 

[...]

quoted

You'd probably need something like commit 3e25f800afb82bd9e5f8 ("memory:
fsl_ifc: populate child devices without relying on simple-bus") and the 
subsequent fix in dd8adc713b1656 ("memory: fsl_ifc: populate child
nodes of buses and mfd devices")...

I'm curious what the reasoning was for removing simple-bus from IFC.  It
seems that the schema verification also played a role in that:
https://www.spinics.net/lists/devicetree/msg220418.html

If a kernel change is needed to support changed .dts files, then we 
shouldn't be doing that here (being mature platforms). That would mean 
new DTB will not work with existing kernels.

Alright, I'll keep simple-bus in the eLBC binding for historical
compatibility.


Thank you both for your discussion.


J. Neuschäfer