diff mbox series

[v2,1/2] dt-bindings: mtd: partitions: Add binding for Sercomm parser

Message ID 0450d781-c506-c28e-a0e5-435bee16721f@gmail.com
State New
Headers show
Series [v2,1/2] dt-bindings: mtd: partitions: Add binding for Sercomm parser | expand

Commit Message

Mikhail Zhilkin April 30, 2022, 8:04 a.m. UTC 
On 4/29/2022 11:22 PM, Krzysztof Kozlowski wrote:

>>>> Real dts:
>>>>
>>>> Link:
>>>> https://github.com/openwrt/openwrt/blob/edcc1a9a734bb3fcdc9242025290d3f173e71b78/target/linux/ramips/dts/mt7621_beeline_smartbox-giga.dts#L79
>>>>
>>>> So, I currently found another solution - to extend fixed-partitions.yaml
>>>> with "sercomm,sc-partitions". Is It ok from your side? Can I use this
>>>> code in v3?
>>> Not really, I don't understand why do you need it 
>> The main idea is keeping original Sercomm firmware behavior:
>>
>> 1. If dynamic partition map found then use offsets and mtd sizes stored
>> in partition map. It's provided by "sercomm,sc-partitions" compatible.
>>
>> 2. If dynamic partition map doesn't exist or broken then default values
>> (from dts) are used. It's provided by "fixed-partitions" compatible.
> Then you need to adjust fixed-partitions for such case. See syscon case
> (all over the tree and Documentation/devicetree/bindings/mfd/syscon.yaml).

Thanks! Here's what I got (neither errors nor warnings). I also updated
the parser itself by adding the vendor prefix and tested on a real device. 

 .../mtd/partitions/fixed-partitions.yaml      | 61 ++++++++++++++++++-
 1 file changed, 59 insertions(+), 2 deletions(-)

Comments

Mikhail Zhilkin May 1, 2022, 2:51 p.m. UTC | #1 
On 5/1/2022 11:17 AM, Krzysztof Kozlowski wrote:

> On 30/04/2022 20:54, Mikhail Zhilkin wrote:
>>  patternProperties:
>>    "@[0-9a-f]+$":
>> -    $ref: "partition.yaml#"
>> +    allOf:
>> +      - $ref: "partition.yaml#"
>> +      - if:
>> +          properties:
>> +            compatible:
>> +              contains:
>> +                const: sercomm,sc-partitions
>> +        then:
>> +          properties:
>> +            sercomm,scpart-id:
>> +              description: Partition id in Sercomm partition map. Parser
>> +                uses this id to get partition offset and size values from
>> +                dynamic partition map.
> Partition offset and size values are not derived from scpart-id. I am
> sorry but after all these questions - it's the third time now - you
> never answer why do you need this property and what is it used for. From
> all the examples it could be simply removed and the partition map will
> be exactly the same.
scpart-id is necessary to get (using mtd parser) partition offset and
size from dynamic partition map (NOT from the reg property):

❯ xxd -e -c 12 -s $((0x800)) -l $((0x78)) mtd1
00000800: 00000000 00000000 00100000  ............
0000080c: 00000001 00100000 00100000  ............
00000818: 00000002 00200000 00100000  ...... .....
00000824: 00000003 00300000 00100000  ......0.....
00000830: 00000004 00400000 00600000  ......@...`.
0000083c: 00000005 00a00000 00600000  ..........`.
00000848: 00000006 01000000 02000000  ............
00000854: 00000007 03000000 02000000  ............
00000860: 00000008 05000000 01400000  ..........@.
0000086c: 00000009 06400000 01b80000  ......@.....
          scpart-id  offset      size

With sercomm,sc-partitions the reg property will be ignored (offset =
0x200000, size = 0x100000) and the values will be taken from partition map.

For example we have this is dts:

partition@200000 {
            label = "Factory";
            reg = <0x200000 0x100000>;
            sercomm,scpart-id = <2>;
            read-only;
        };

Dynamic partition map:

scpart-id = 2; offset = 0x00200000; size = 0x00100000

00000002 00200000 00100000  ...... .....

In this example the offset and size are the same in reg and dynamic
partition map. If device have bad blocks on NAND the values will be a
little different. And we have to take partition offsets from partition
map to avoid boot loops, wrong eeprom location and other bad things.

Is there anything that needs to be explained in more detail?

> Best regards,
> Krzysztof
Krzysztof Kozlowski May 1, 2022, 4:17 p.m. UTC | #2 
On 01/05/2022 16:51, Mikhail Zhilkin wrote:
> On 5/1/2022 11:17 AM, Krzysztof Kozlowski wrote:
> 
>> On 30/04/2022 20:54, Mikhail Zhilkin wrote:
>>>  patternProperties:
>>>    "@[0-9a-f]+$":
>>> -    $ref: "partition.yaml#"
>>> +    allOf:
>>> +      - $ref: "partition.yaml#"
>>> +      - if:
>>> +          properties:
>>> +            compatible:
>>> +              contains:
>>> +                const: sercomm,sc-partitions
>>> +        then:
>>> +          properties:
>>> +            sercomm,scpart-id:
>>> +              description: Partition id in Sercomm partition map. Parser
>>> +                uses this id to get partition offset and size values from
>>> +                dynamic partition map.
>> Partition offset and size values are not derived from scpart-id. I am
>> sorry but after all these questions - it's the third time now - you
>> never answer why do you need this property and what is it used for. From
>> all the examples it could be simply removed and the partition map will
>> be exactly the same.
> scpart-id is necessary to get (using mtd parser) partition offset and
> size from dynamic partition map (NOT from the reg property):
> 
> ❯ xxd -e -c 12 -s $((0x800)) -l $((0x78)) mtd1
> 00000800: 00000000 00000000 00100000  ............
> 0000080c: 00000001 00100000 00100000  ............
> 00000818: 00000002 00200000 00100000  ...... .....
> 00000824: 00000003 00300000 00100000  ......0.....
> 00000830: 00000004 00400000 00600000  ......@...`.
> 0000083c: 00000005 00a00000 00600000  ..........`.
> 00000848: 00000006 01000000 02000000  ............
> 00000854: 00000007 03000000 02000000  ............
> 00000860: 00000008 05000000 01400000  ..........@.
> 0000086c: 00000009 06400000 01b80000  ......@.....
>           scpart-id  offset      size
> 
> With sercomm,sc-partitions the reg property will be ignored (offset =
> 0x200000, size = 0x100000) and the values will be taken from partition map.
> 
> For example we have this is dts:
> 
> partition@200000 {
>             label = "Factory";
>             reg = <0x200000 0x100000>;
>             sercomm,scpart-id = <2>;
>             read-only;
>         };
> 
> Dynamic partition map:
> 
> scpart-id = 2; offset = 0x00200000; size = 0x00100000
> 
> 00000002 00200000 00100000  ...... .....
> 
> In this example the offset and size are the same in reg and dynamic
> partition map. If device have bad blocks on NAND the values will be a
> little different. And we have to take partition offsets from partition
> map to avoid boot loops, wrong eeprom location and other bad things.
> 
> Is there anything that needs to be explained in more detail?

Thanks a lot, this clarifies the topic. Looks good. Maybe you could put
parts of this into the scpart-id field description?

Best regards,
Krzysztof
diff mbox series

Patch

diff --git
a/Documentation/devicetree/bindings/mtd/partitions/fixed-partitions.yaml
b/Documentation/devicetree/bindings/mtd/partitions/fixed-partitions.yaml
index ea4cace6a955..fa457d55559b 100644
--- a/Documentation/devicetree/bindings/mtd/partitions/fixed-partitions.yaml
+++ b/Documentation/devicetree/bindings/mtd/partitions/fixed-partitions.yaml
@@ -17,9 +17,29 @@  description: |
 maintainers:
   - Rafał Miłecki <rafal@milecki.pl>
 
+select:
+  properties:
+    compatible:
+      contains:
+        enum:
+          - fixed-partitions
+
+  required:
+    - compatible
+
 properties:
   compatible:
-    const: fixed-partitions
+    anyOf:
+      - items:
+          - enum:
+              - sercomm,sc-partitions
+
+          - const: fixed-partitions
+
+      - contains:
+          const: fixed-partitions
+        minItems: 1
+        maxItems: 2
 
   "#address-cells": true
 
@@ -27,7 +47,18 @@  properties:
 
 patternProperties:
   "@[0-9a-f]+$":
-    $ref: "partition.yaml#"
+    allOf:
+      - $ref: "partition.yaml#"
+      - if:
+          properties:
+            compatible:
+              contains:
+                const: sercomm,sc-partitions
+        then:
+          properties:
+            sercomm,scpart-id:
+              description: Partition id in Sercomm partition map
+              $ref: /schemas/types.yaml#/definitions/uint32
 
 required:
   - "#address-cells"
@@ -119,3 +150,29 @@  examples:
             };
         };
     };
+  - |
+    partitions {
+        compatible = "sercomm,sc-partitions", "fixed-partitions";
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        partition@0 {
+            label = "u-boot";
+            reg = <0x0 0x100000>;
+            sercomm,scpart-id=<0>;
+            read-only;
+        };
+
+        partition@100000 {
+            label = "dynamic partition map";
+            reg = <0x100000 0x100000>;
+            sercomm,scpart-id = <1>;
+        };
+
+        partition@200000 {
+            label = "Factory";
+            reg = <0x200000 0x100000>;
+            sercomm,scpart-id = <2>;
+            read-only;
+        };
+    };