Re: [PATCH v2 04/24] dt-bindings: net: dwmac: Refactor snps,*-config properties

On Tue, Feb 09, 2021 at 04:26:08PM -0600, Rob Herring wrote:

On Mon, Feb 08, 2021 at 04:55:48PM +0300, Serge Semin wrote:

quoted

Currently the "snps,axi-config", "snps,mtl-rx-config" and
"snps,mtl-tx-config" properties are declared as a single phandle reference
to a node with corresponding parameters defined. That's not good for
several reasons. First of all scattering around a device tree some
particular device-specific configs with no visual relation to that device
isn't suitable from maintainability point of view. That leads to a
disturbed representation of the actual device tree mixing actual device
nodes and some vendor-specific configs. Secondly using the same configs
set for several device nodes doesn't represent well the devices structure,
since the interfaces these configs describe in hardware belong to
different devices and may actually differ. In the later case having the
configs node separated from the corresponding device nodes gets to be
even unjustified.

So instead of having a separate DW *MAC configs nodes we suggest to
define them as sub-nodes of the device nodes, which interfaces they
actually describe. By doing so we'll make the DW *MAC nodes visually
correct describing all the aspects of the IP-core configuration. Thus
we'll be able to describe the configs sub-nodes bindings right in the
snps,dwmac.yaml file.

Note the former "snps,axi-config", "snps,mtl-rx-config" and
"snps,mtl-tx-config" properties have been marked as deprecated in favor of
the added by this commit "axi-config", "mtl-rx-config" and "mtl-tx-config"
sub-nodes respectively.

Signed-off-by: Serge Semin <redacted>

---

Note this change will work only if DT-schema tool is fixed like this:

--- a/meta-schemas/nodes.yaml	2021-02-08 14:20:56.732447780 +0300
+++ b/meta-schemas/nodes.yaml	2021-02-08 14:21:00.736492245 +0300

@@ -22,6 +22,7 @@
     - unevaluatedProperties
     - deprecated
     - required
+    - not
     - allOf
     - anyOf
     - oneOf

Can you send me a patch or GH PR. There is another way to express. More 
below.

Ok. I'll send a patch. To what email and mailing lists shall I send it
to?

quoted

So a property with name "not" would be allowed and the "not-required"
pattern would work.

Changelog v2:
- Add the new sub-nodes "axi-config", "mtl-rx-config" and "mtl-tx-config"
  describing the nodes now deprecated properties were supposed to
  refer to.
- Fix invalid identation in the "snps,route-*" property settings.
- Use correct syntax of the JSON pointers, so the later would begin
  with a '/' after the '#'.
---
 .../devicetree/bindings/net/snps,dwmac.yaml   | 389 +++++++++++++-----
 1 file changed, 297 insertions(+), 92 deletions(-)

diff --git a/Documentation/devicetree/bindings/net/snps,dwmac.yaml b/Documentation/devicetree/bindings/net/snps,dwmac.yaml
index 03d58bf9965f..4dda9ffa822c 100644
--- a/Documentation/devicetree/bindings/net/snps,dwmac.yaml
+++ b/Documentation/devicetree/bindings/net/snps,dwmac.yaml

@@ -150,73 +150,264 @@ properties:
       in a different mode than the PHY in order to function.
 
   snps,axi-config:
+    deprecated: true
     $ref: /schemas/types.yaml#/definitions/phandle
     description:
-      AXI BUS Mode parameters. Phandle to a node that can contain the
-      following properties
-        * snps,lpi_en, enable Low Power Interface
-        * snps,xit_frm, unlock on WoL
-        * snps,wr_osr_lmt, max write outstanding req. limit
-        * snps,rd_osr_lmt, max read outstanding req. limit
-        * snps,kbbe, do not cross 1KiB boundary.
-        * snps,blen, this is a vector of supported burst length.
-        * snps,fb, fixed-burst
-        * snps,mb, mixed-burst
-        * snps,rb, rebuild INCRx Burst
+      AXI BUS Mode parameters. Phandle to a node that contains the properties
+      described in the 'axi-config' sub-node.
+
+  axi-config:
+    type: object
+    description: AXI BUS Mode parameters
+
+    properties:
+      snps,lpi_en:
+        $ref: /schemas/types.yaml#/definitions/flag
+        description: Enable Low Power Interface
+
+      snps,xit_frm:
+        $ref: /schemas/types.yaml#/definitions/flag
+        description: Unlock on WoL
+
+      snps,wr_osr_lmt:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        description: Max write outstanding req. limit
+        default: 1
+        minimum: 0
+        maximum: 15
+
+      snps,rd_osr_lmt:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        description: Max read outstanding req. limit
+        default: 1
+        minimum: 0
+        maximum: 15
+
+      snps,kbbe:
+        $ref: /schemas/types.yaml#/definitions/flag
+        description: Do not cross 1KiB boundary
+
+      snps,blen:
+        $ref: /schemas/types.yaml#/definitions/uint32-array
+        description: A vector of supported burst lengths
+        minItems: 7
+        maxItems: 7
+        items:
+          enum: [256, 128, 64, 32, 16, 8, 4, 0]
+
+      snps,fb:
+        $ref: /schemas/types.yaml#/definitions/flag
+        description: Fixed-burst
+
+      snps,mb:
+        $ref: /schemas/types.yaml#/definitions/flag
+        description: Mixed-burst
+
+      snps,rb:
+        $ref: /schemas/types.yaml#/definitions/flag
+        description: Rebuild INCRx Burst
+
+    additionalProperties: false
 
   snps,mtl-rx-config:

You could keep these pointing to child nodes to avoid driver changes.

Right, but I'd prefer having the AXI/MTL-config nodes directly found
because they are supposed to be defined as sub-nodes anyway. Having
the snps-prefixed AXI/MTL-config properties with phandle reference are
going to be marked as deprecated. By doing so we'll discourage
defining the DW MAC-related configs scattered around the new dts-es. 

quoted

+    deprecated: true
     $ref: /schemas/types.yaml#/definitions/phandle
     description:
-      Multiple RX Queues parameters. Phandle to a node that can
-      contain the following properties
-        * snps,rx-queues-to-use, number of RX queues to be used in the
-          driver
-        * Choose one of these RX scheduling algorithms
-          * snps,rx-sched-sp, Strict priority
-          * snps,rx-sched-wsp, Weighted Strict priority
-        * For each RX queue
-          * Choose one of these modes
-            * snps,dcb-algorithm, Queue to be enabled as DCB
-            * snps,avb-algorithm, Queue to be enabled as AVB
-          * snps,map-to-dma-channel, Channel to map
-          * Specifiy specific packet routing
-            * snps,route-avcp, AV Untagged Control packets
-            * snps,route-ptp, PTP Packets
-            * snps,route-dcbcp, DCB Control Packets
-            * snps,route-up, Untagged Packets
-            * snps,route-multi-broad, Multicast & Broadcast Packets
-          * snps,priority, bitmask of the tagged frames priorities assigned to
-            the queue
+      Multiple RX Queues parameters. Phandle to a node that contains the
+      properties described in the 'mtl-rx-config' sub-node.
+
+  mtl-rx-config:
+    type: object
+    description: Multiple RX Queues parameters
+
+    properties:
+      snps,rx-queues-to-use:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        description: Number of RX queues to be used in the driver
+        default: 1
+        minimum: 1
+
+    patternProperties:
+      "^snps,rx-sched-(sp|wsp)$":
+        $ref: /schemas/types.yaml#/definitions/flag
+        description: Strict/Weighted Strict RX scheduling priority
+
+      "^queue[0-9]$":
+        type: object
+        description: Each RX Queue parameters
+
+        properties:
+          snps,map-to-dma-channel:
+            $ref: /schemas/types.yaml#/definitions/uint32
+            description: DMA channel to map
+
+          snps,priority:
+            $ref: /schemas/types.yaml#/definitions/uint32
+            description: RX queue priority
+            minimum: 0
+            maximum: 15
+
+        patternProperties:
+          "^snps,(dcb|avb)-algorithm$":
+            $ref: /schemas/types.yaml#/definitions/flag
+            description: Enable Queue as DCB/AVB
+
+          "^snps,route-(avcp|ptp|dcbcp|up|multi-broad)$":
+            $ref: /schemas/types.yaml#/definitions/flag
+            description:
+              AV Untagged/PTP/DCB Control/Untagged/Multicast & Broadcast
+              packets routing respectively.
+
+        additionalProperties: false
+
+        # Choose only one of the Queue modes and the packets routing
+        allOf:
+          - not:
+              required:
+                - snps,dcb-algorithm
+                - snps,avb-algorithm
+          - oneOf:
+              - required:
+                  - snps,route-avcp
+              - required:
+                  - snps,route-ptp
+              - required:
+                  - snps,route-dcbcp
+              - required:
+                  - snps,route-up
+              - required:
+                  - snps,route-multi-broad
+              - not:
+                  anyOf:
+                    - required:
+                        - snps,route-avcp
+                    - required:
+                        - snps,route-ptp
+                    - required:
+                        - snps,route-dcbcp
+                    - required:
+                        - snps,route-up
+                    - required:
+                        - snps,route-multi-broad

This 'not: ..." could be:

properties:
  snps,route-avcp: false
  snps,route-ptp: false
  snps,route-dcbcp: false
  snps,route-up: false
  snps,route-multi-broad: false

Not sure which one is better. Using required everywhere or more 
concise...

Thanks for suggesting an alternative. I didn't figure out such option
myself. Though in this case since we need to use the required property
anyway, I'd prefer to have it used in the 'not' sub-schema too. At
least for uniformity and to simplify the conditional statement
readability, even if it causes a bit of the concise loss.

(Really, 'route' should have taken a value and the schema would be 
greatly simplified. Oh well.)

Yeah, I had the same thought in mind when first saw that
boolean-properties hell. There are few more properties in this
bindings file which should have been also defined as taking values
instead of being booleans...

quoted

+
+    additionalProperties: false
+
+    # Choose one of the RX scheduling algorithms
+    not:
+      required:
+        - snps,rx-sched-sp
+        - snps,rx-sched-wsp

I guess this is the problematic one. The rest should be hidden behind 
conditionals (a common loophole in meta-schema checks). You could do 
that here:

allOf:
  - not:
      ...

Oh, thanks. I can't believe I've missed that option. Though fixing the
dt-schema tool would be better than using the combining schema
keywords as a workaround.

But why not just make one of the 2 properties required? You're already 
changing things. 

First of all the driver permits omitting all of them in the
corresponding nodes and implicitly using one of the properties by
default (the same thing is for the MTL Tx-queues). If we made some of
them being required we would have broken the driver dts-contract,
which is not good. Secondly I'd have to fix the
arch/arm/boot/dts/artpec6.dtsi dts file too, which would have been an
additional patch in the series, additional work, additional review
from the platform maintainer, additional merge path, etc. So to speak
that would cause more troubles, than just using the "not:" statement
here.)

-Sergey

Rob