[PATCH 0/2] Add board-id support for multiple DT selection

[PATCH 0/2] Add board-id support for multiple DT selection

[Amrit Anand]

Device manufacturers frequently ship multiple boards or SKUs under a
single software package. These software packages will ship multiple
devicetree blobs and require some mechanism to pick the correct DTB for
the board the software package was deployed. Introduce a common
definition for adding board identifiers to device trees. board-id
provides a mechanism for bootloaders to select the appropriate DTB which
is vendor/OEM-agnostic.

Isn't that what the compatible property is for?
-----------------------------------------------
The compatible property can be used for board matching, but requires
bootloaders and/or firmware to maintain a database of possible strings
to match against or have complex compatible string matching. Compatible
string matching becomes complicated when there are multiple versions of
board: the device tree selector should recognize a DTB that cares to
distinguish between v1/v2 and a DTB that doesn't make the distinction.
An eeprom either needs to store the compatible strings that could match
against the board or the bootloader needs to have vendor-specific
decoding logic for the compatible string. Neither increasing eeprom
storage nor adding vendor-specific decoding logic is desirable.

The solution proposed here is simpler to implement and doesn't require
updating firmware or bootloader for every new board.

How is this better than Qualcomm's qcom,msm-id/qcom,board-id?
-------------------------------------------------------------
The selection process for devicetrees was Qualcomm-specific and not
useful for other devices and bootloaders that were not developed by
Qualcomm because a complex algorithm was used to implement. Board-ids
provide a matching solution that can be implemented by bootloaders
without introducing vendor-specific code. Qualcomm uses three
devicetree properties: msm-id (interchangeably: soc-id), board-id, and
pmic-id.  This does not scale well for use casese which use identifiers,
for example, to distinguish between a display panel. For a display
panel, an approach could be to add a new property: display-id, but now
bootloaders need to be updated to also read this property. We want to
avoid requiring to update bootloaders with new hardware identifiers: a
bootloader need only recognize the identifiers it can handle.

Amrit Anand (1):
  dt-bindings: hwinfo: Add Qualcomm's board-id types

Elliot Berman (1):
  dt-bindings: hwinfo: Introduce board-id

 .../devicetree/bindings/hwinfo/board-id.yaml       | 53 +++++++++++++
 .../devicetree/bindings/hwinfo/qcom,board-id.yaml  | 86 ++++++++++++++++++++++
 include/dt-bindings/arm/qcom,ids.h                 | 68 +++++++++++++++--
 3 files changed, 199 insertions(+), 8 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/hwinfo/board-id.yaml
 create mode 100644 Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml

-- 
2.7.4

[PATCH 1/2] dt-bindings: hwinfo: Introduce board-id

[Amrit Anand]

From: Elliot Berman <quic_eberman@quicinc.com>

Device manufacturers frequently ship multiple boards or SKUs under a
single software package. These software packages will ship multiple
devicetree blobs and require some mechanism to pick the correct DTB for
the board the software package was deployed. Introduce a common
definition for adding board identifiers to device trees. board-id
provides a mechanism for bootloaders to select the appropriate DTB which
is vendor/OEM-agnostic.

Isn't that what the compatible property is for?
-----------------------------------------------
The compatible property can be used for board matching, but requires
bootloaders and/or firmware to maintain a database of possible strings
to match against or have complex compatible string matching. Compatible
string matching becomes complicated when there are multiple versions of
board: the device tree selector should recognize a DTB that cares to
distinguish between v1/v2 and a DTB that doesn't make the distinction.
An eeprom either needs to store the compatible strings that could match
against the board or the bootloader needs to have vendor-specific
decoding logic for the compatible string. Neither increasing eeprom
storage nor adding vendor-specific decoding logic is desirable.

The solution proposed here is simpler to implement and doesn't require
updating firmware or bootloader for every new board.

How is this better than Qualcomm's qcom,msm-id/qcom,board-id?
-------------------------------------------------------------
The selection process for devicetrees was Qualcomm-specific and not
useful for other devices and bootloaders that were not developed by
Qualcomm because a complex algorithm was used to implement. Board-ids
provide a matching solution that can be implemented by bootloaders
without introducing vendor-specific code. Qualcomm uses three
devicetree properties: msm-id (interchangeably: soc-id), board-id, and
pmic-id.  This does not scale well for use casese which use identifiers,
for example, to distinguish between a display panel. For a display
panel, an approach could be to add a new property: display-id,
but now	bootloaders need to be updated to also read this property. We
want to	avoid requiring to update bootloaders with new hardware
identifiers: a bootloader need only recognize the identifiers it can
handle.

Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
Signed-off-by: Amrit Anand <quic_amrianan@quicinc.com>
---
 .../devicetree/bindings/hwinfo/board-id.yaml       | 53 ++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwinfo/board-id.yaml

diff --git a/Documentation/devicetree/bindings/hwinfo/board-id.yaml b/Documentation/devicetree/bindings/hwinfo/board-id.yaml
new file mode 100644
index 0000000..82d5ff7
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwinfo/board-id.yaml
@@ -0,0 +1,53 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwinfo/board-id.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Board Identifier for Devicetree Selection
+
+maintainers:
+  - Amrit Anand <quic_amrianan@quicinc.com>
+  - Elliot Berman <quic_eberman@quicinc.com>
+
+description: |
+  Device manufacturers frequently ship multiple boards under a single
+  software package. These software packages will ship multiple devicetree
+  blobs and require some mechanism to pick the correct DTB for the board
+  the software package was deployed. board-id provides a mechanism for
+  bootloaders to select the appropriate DTB which is vendor/OEM-agnostic.
+
+select:
+  anyOf:
+    - required:
+        - 'board-id'
+    - required:
+        - 'board-id-types'
+    - required:
+        - '#board-id-cells'
+
+properties:
+  $nodename:
+    const: "/"
+  board-id:
+    $ref: /schemas/types.yaml#/definitions/uint32-matrix
+    description: |
+      A list of identifiers that can be used to match with this devicetree.
+      The interpretatation of each cell can be matched with the
+      board-id-type at the same index.
+
+  board-id-types:
+    $ref: /schemas/types.yaml#/definitions/non-unique-string-array
+    description:
+      Defines the type of each cell, indicating to the DeviceTree selection
+      mechanism how to parse the board-id.
+
+  '#board-id-cells':
+    minimum: 1
+
+required:
+  - board-id
+  - board-id-types
+  - '#board-id-cells'
+
+additionalProperties: true
-- 
2.7.4

[PATCH 2/2] dt-bindings: hwinfo: Add Qualcomm's board-id types

[Amrit Anand]

Qualcomm based DT uses two or three different identifiers. The SoC
based idenfier which signifies chipset and the revision for those
chipsets. The board based identifier is used to distinguish different
boards (e.g. IDP, MTP) along with the different types of same boards.
The PMIC attached to the board can also be used as a identifier for
device tree.

Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
Signed-off-by: Amrit Anand <quic_amrianan@quicinc.com>
---
 .../devicetree/bindings/hwinfo/qcom,board-id.yaml  | 86 ++++++++++++++++++++++
 include/dt-bindings/arm/qcom,ids.h                 | 68 +++++++++++++++--
 2 files changed, 146 insertions(+), 8 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml

diff --git a/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml b/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
new file mode 100644
index 0000000..807f134
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
@@ -0,0 +1,86 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwinfo/qcom,board-id.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: QCOM Board Identifier for Devicetree Selection
+
+maintainers:
+  - Amrit Anand <quic_amrianan@quicinc.com>
+  - Elliot Berman <quic_eberman@quicinc.com>
+
+description: |
+  Qualcomm uses two and sometimes three hardware identifiers to describe
+  its boards
+      - a SoC identifier is used to match chipsets (e.g. sm8550 vs sm8450)
+      - a board identifier is used to match board form factor (e.g. MTP, QRD,
+        ADP, CRD)
+      - a PMIC identifier is occasionally used when different PMICs are used
+        for a given board/SoC combination.
+  Each field and helper macros are defined at::
+      - include/dt-bindings/arm/qcom,ids.h
+
+  For example,
+    / {
+        #board-id-cells = <2>;
+        board-id = <456 0>, <457 0>, <10 0>;
+        board-id-types = "qcom,soc-id", "qcom,soc-id", "qcom,board-id";
+     }
+
+allOf:
+  - $ref: board-id.yaml#
+
+properties:
+  board-id:
+    minItems: 2
+
+  board-id-types:
+    minItems: 2
+    items:
+      oneOf:
+        - const: qcom,soc-id
+          description: |
+            Matches Qualcomm Technologies, Inc. boards with the specified SoC.
+            2 integers are needed to describe a soc-id. The first integer is the
+            SoC ID and the second integer is the SoC revision.
+            qcom,soc-id = <soc-id  soc-revision>
+        - const: qcom,board-id
+          description: |
+            Matches Qualcomm Technologies, Inc. boards with the specified board.
+            2 integers are needed to describe a board-id. The first integer is the
+            board ID. The second integer is the board-subtype.
+            qcom,board-id = <board-id  board-subtype>
+        - const: qcom,pmic-id
+          description: |
+            QUALCOMM boards can be atached to mutliple PMICs where slave-id (SID)
+            indicates the address of the bus on which the PMIC is attached. It can be
+            any number. The model for a PMIC indicates the PMIC name attached to bus
+            described by SID along with  major and minor version. 2 integers are needed
+            to describe qcom,pmic-id. The first integer is the slave-id and the second integer
+            is the pmic model.
+            qcom,pmic-id = <pmic-sid pmic-model>
+
+  '#board-id-cells':
+    minimum: 2
+
+additionalProperties: true
+
+examples:
+   - |
+     #include <dt-bindings/arm/qcom,ids.h>
+     / {
+         model = "Qualcomm Technologies, Inc. sc7280 IDP SKU1 platform";
+         compatible = "qcom,sc7280-idp", "google,senor", "qcom,sc7280";
+
+         #board-id-cells = <2>;
+         board-id = <QCOM_SOC_ID(SC7280) QCOM_SOC_REVISION(1)>,
+                    <QCOM_SOC_ID(SC7280) QCOM_SOC_REVISION(2)>,
+                    <QCOM_BOARD_ID(IDP, 1, 0) QCOM_BOARD_SUBTYPE(UFS, ANY, 1)>;
+         board-id-types = "qcom,soc-id",
+                          "qcom,soc-id",
+                          "qcom,board-id";
+
+         #address-cells = <2>;
+         #size-cells = <2>;
+      };
diff --git a/include/dt-bindings/arm/qcom,ids.h b/include/dt-bindings/arm/qcom,ids.h
index f724834..c4cd440 100644
--- a/include/dt-bindings/arm/qcom,ids.h
+++ b/include/dt-bindings/arm/qcom,ids.h
@@ -8,9 +8,12 @@
 #define _DT_BINDINGS_ARM_QCOM_IDS_H
 
 /*
- * The MSM chipset and hardware revision used by Qualcomm bootloaders, DTS for
- * older chipsets (qcom,msm-id) and in socinfo driver:
+ * The MSM chipset ID used by Qualcomm bootloaders, DTS for
+ * older chipsets (soc-id) and in socinfo driver:
  */
+
+#define QCOM_SOC_ID(a)  ((QCOM_ID_##a) && 0xffff)
+
 #define QCOM_ID_MSM8260			70
 #define QCOM_ID_MSM8660			71
 #define QCOM_ID_APQ8060			86
@@ -266,16 +269,65 @@
 #define QCOM_ID_IPQ5302			595
 #define QCOM_ID_IPQ5300			624
 
+ /* The SOC revision used by Qualcomm bootloaders (soc-revision) */
+
+#define QCOM_SOC_REVISION(a)		(a & 0xff)
+
 /*
  * The board type and revision information, used by Qualcomm bootloaders and
- * DTS for older chipsets (qcom,board-id):
+ * DTS for older chipsets (board-id)
  */
+
 #define QCOM_BOARD_ID(a, major, minor) \
-	(((major & 0xff) << 16) | ((minor & 0xff) << 8) | QCOM_BOARD_ID_##a)
+	(((major & 0xff) << 16) | ((minor & 0xff) << 8) | ((QCOM_BOARD_ID_##a) & 0xff))
+
+#define QCOM_BOARD_ID_MTP		0x8
+#define QCOM_BOARD_ID_DRAGONBOARD	0x10
+#define QCOM_BOARD_ID_QRD		0x11
+#define QCOM_BOARD_ID_HDK		0x1F
+#define QCOM_BOARD_ID_ATP		0x21
+#define QCOM_BOARD_ID_IDP		0x22
+#define QCOM_BOARD_ID_SBC		0x24
+#define QCOM_BOARD_ID_QXR		0x26
+#define QCOM_BOARD_ID_CRD		0x28
+
+/*
+ * The platform subtype is used by Qualcomm bootloaders and
+ * DTS (board-subtype)
+ */
+#define QCOM_BOARD_SUBTYPE(a, b, SUBTYPE) \
+	(((QCOM_BOARD_BOOT_##a & 0xf) << 16) | ((QCOM_BOARD_DDRTYPE_##b & 0x7) << 8) | \
+	(SUBTYPE & 0xff))
+
+/* Board DDR Type where each value indicates higher limit */
+#define QCOM_BOARD_DDRTYPE_ANY		0x0
+#define QCOM_BOARD_DDRTYPE_128M		0x1
+#define QCOM_BOARD_DDRTYPE_256M		0x2
+#define QCOM_BOARD_DDRTYPE_512M		0x3
+#define QCOM_BOARD_DDRTYPE_1024M	0x4
+#define QCOM_BOARD_DDRTYPE_2048M	0x5
+#define QCOM_BOARD_DDRTYPE_3072M	0x6
+#define QCOM_BOARD_DDRTYPE_4096M	0x7
+
+/* Board Boot Device Type */
+#define QCOM_BOARD_BOOT_EMMC		0x0
+#define QCOM_BOARD_BOOT_UFS		0x1
+#define QCOM_BOARD_BOOT_NAND		0x2
+#define QCOM_BOARD_BOOT_OTHER		0x3
+
+/*
+ * The PMIC slave id is used by Qualcomm bootloaders to
+ * indicates which PMIC is attached (pmic-sid)
+ */
+
+#define QCOM_PMIC_SID(a)		(a & 0xff)
+
+/*
+ * The PMIC ID is used by Qualcomm bootloaders to describe the ID
+ * of PMIC attached to bus described by SID (pmic-model)
+ */
 
-#define QCOM_BOARD_ID_MTP			8
-#define QCOM_BOARD_ID_DRAGONBOARD		10
-#define QCOM_BOARD_ID_QRD			11
-#define QCOM_BOARD_ID_SBC			24
+#define QCOM_PMIC_MODEL(ID, major, minor) \
+	(((major & 0xff) << 16) | ((minor & 0xff) << 8) | (ID & 0xff))
 
 #endif /* _DT_BINDINGS_ARM_QCOM_IDS_H */
-- 
2.7.4

Re: [PATCH 1/2] dt-bindings: hwinfo: Introduce board-id

[Rob Herring]

On Sat, 20 Jan 2024 16:50:48 +0530, Amrit Anand wrote:
> From: Elliot Berman <quic_eberman@quicinc.com>
> 
> Device manufacturers frequently ship multiple boards or SKUs under a
> single software package. These software packages will ship multiple
> devicetree blobs and require some mechanism to pick the correct DTB for
> the board the software package was deployed. Introduce a common
> definition for adding board identifiers to device trees. board-id
> provides a mechanism for bootloaders to select the appropriate DTB which
> is vendor/OEM-agnostic.
> 
> Isn't that what the compatible property is for?
> -----------------------------------------------
> The compatible property can be used for board matching, but requires
> bootloaders and/or firmware to maintain a database of possible strings
> to match against or have complex compatible string matching. Compatible
> string matching becomes complicated when there are multiple versions of
> board: the device tree selector should recognize a DTB that cares to
> distinguish between v1/v2 and a DTB that doesn't make the distinction.
> An eeprom either needs to store the compatible strings that could match
> against the board or the bootloader needs to have vendor-specific
> decoding logic for the compatible string. Neither increasing eeprom
> storage nor adding vendor-specific decoding logic is desirable.
> 
> The solution proposed here is simpler to implement and doesn't require
> updating firmware or bootloader for every new board.
> 
> How is this better than Qualcomm's qcom,msm-id/qcom,board-id?
> -------------------------------------------------------------
> The selection process for devicetrees was Qualcomm-specific and not
> useful for other devices and bootloaders that were not developed by
> Qualcomm because a complex algorithm was used to implement. Board-ids
> provide a matching solution that can be implemented by bootloaders
> without introducing vendor-specific code. Qualcomm uses three
> devicetree properties: msm-id (interchangeably: soc-id), board-id, and
> pmic-id.  This does not scale well for use casese which use identifiers,
> for example, to distinguish between a display panel. For a display
> panel, an approach could be to add a new property: display-id,
> but now	bootloaders need to be updated to also read this property. We
> want to	avoid requiring to update bootloaders with new hardware
> identifiers: a bootloader need only recognize the identifiers it can
> handle.
> 
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> Signed-off-by: Amrit Anand <quic_amrianan@quicinc.com>
> ---
>  .../devicetree/bindings/hwinfo/board-id.yaml       | 53 ++++++++++++++++++++++
>  1 file changed, 53 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/hwinfo/board-id.yaml
> 

My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
on your patch (DT_CHECKER_FLAGS is new in v5.13):

yamllint warnings/errors:
./Documentation/devicetree/bindings/hwinfo/board-id.yaml:23:11: [error] string value is redundantly quoted with any quotes (quoted-strings)
./Documentation/devicetree/bindings/hwinfo/board-id.yaml:25:11: [error] string value is redundantly quoted with any quotes (quoted-strings)

dtschema/dtc warnings/errors:

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/1705749649-4708-2-git-send-email-quic_amrianan@quicinc.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.

Re: [PATCH 2/2] dt-bindings: hwinfo: Add Qualcomm's board-id types

[Rob Herring]

On Sat, 20 Jan 2024 16:50:49 +0530, Amrit Anand wrote:
> Qualcomm based DT uses two or three different identifiers. The SoC
> based idenfier which signifies chipset and the revision for those
> chipsets. The board based identifier is used to distinguish different
> boards (e.g. IDP, MTP) along with the different types of same boards.
> The PMIC attached to the board can also be used as a identifier for
> device tree.
> 
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> Signed-off-by: Amrit Anand <quic_amrianan@quicinc.com>
> ---
>  .../devicetree/bindings/hwinfo/qcom,board-id.yaml  | 86 ++++++++++++++++++++++
>  include/dt-bindings/arm/qcom,ids.h                 | 68 +++++++++++++++--
>  2 files changed, 146 insertions(+), 8 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
> 

My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
on your patch (DT_CHECKER_FLAGS is new in v5.13):

yamllint warnings/errors:
./Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml:70:4: [warning] wrong indentation: expected 2 but found 3 (indentation)

dtschema/dtc warnings/errors:

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/1705749649-4708-3-git-send-email-quic_amrianan@quicinc.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.

Re: [PATCH 0/2] Add board-id support for multiple DT selection

[Konrad Dybcio]

On 20.01.2024 12:20, Amrit Anand wrote:
> Device manufacturers frequently ship multiple boards or SKUs under a
> single software package. These software packages will ship multiple
> devicetree blobs and require some mechanism to pick the correct DTB for
> the board the software package was deployed. Introduce a common
> definition for adding board identifiers to device trees. board-id
> provides a mechanism for bootloaders to select the appropriate DTB which
> is vendor/OEM-agnostic.

Maybe it'd be a good idea to add it to the base spec!

https://github.com/devicetree-org/devicetree-specification

Konrad

Re: [PATCH 2/2] dt-bindings: hwinfo: Add Qualcomm's board-id types

[Konrad Dybcio]

On 20.01.2024 12:20, Amrit Anand wrote:
> Qualcomm based DT uses two or three different identifiers. The SoC
> based idenfier which signifies chipset and the revision for those
> chipsets. The board based identifier is used to distinguish different
> boards (e.g. IDP, MTP) along with the different types of same boards.
> The PMIC attached to the board can also be used as a identifier for
> device tree.
> 
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> Signed-off-by: Amrit Anand <quic_amrianan@quicinc.com>
> ---
>  .../devicetree/bindings/hwinfo/qcom,board-id.yaml  | 86 ++++++++++++++++++++++
>  include/dt-bindings/arm/qcom,ids.h                 | 68 +++++++++++++++--
>  2 files changed, 146 insertions(+), 8 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
> 
> diff --git a/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml b/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
> new file mode 100644
> index 0000000..807f134
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
> @@ -0,0 +1,86 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/hwinfo/qcom,board-id.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: QCOM Board Identifier for Devicetree Selection
> +
> +maintainers:
> +  - Amrit Anand <quic_amrianan@quicinc.com>
> +  - Elliot Berman <quic_eberman@quicinc.com>
> +
> +description: |

The '|'s are unnecessary in both commits, IIRC they're used for
preserving formatting which we don't really need for non-styled
plaintext

> +  Qualcomm uses two and sometimes three hardware identifiers to describe
> +  its boards
> +      - a SoC identifier is used to match chipsets (e.g. sm8550 vs sm8450)
> +      - a board identifier is used to match board form factor (e.g. MTP, QRD,
> +        ADP, CRD)
> +      - a PMIC identifier is occasionally used when different PMICs are used
> +        for a given board/SoC combination.
> +  Each field and helper macros are defined at::
> +      - include/dt-bindings/arm/qcom,ids.h
> +
> +  For example,
> +    / {
> +        #board-id-cells = <2>;
> +        board-id = <456 0>, <457 0>, <10 0>;
> +        board-id-types = "qcom,soc-id", "qcom,soc-id", "qcom,board-id";
> +     }
> +
> +allOf:
> +  - $ref: board-id.yaml#
> +
> +properties:
> +  board-id:
> +    minItems: 2

I believe some older platforms match exclusively based on socid, so
perhaps 1 would be okay as well.

[...]

> +examples:
> +   - |
> +     #include <dt-bindings/arm/qcom,ids.h>
> +     / {
> +         model = "Qualcomm Technologies, Inc. sc7280 IDP SKU1 platform";
> +         compatible = "qcom,sc7280-idp", "google,senor", "qcom,sc7280";
> +
> +         #board-id-cells = <2>;
> +         board-id = <QCOM_SOC_ID(SC7280) QCOM_SOC_REVISION(1)>,
> +                    <QCOM_SOC_ID(SC7280) QCOM_SOC_REVISION(2)>,
> +                    <QCOM_BOARD_ID(IDP, 1, 0) QCOM_BOARD_SUBTYPE(UFS, ANY, 1)>;
> +         board-id-types = "qcom,soc-id",
> +                          "qcom,soc-id",
> +                          "qcom,board-id";

So, would the matching here would be:

loop over disctinct board-id-types
	check if there's at least 1 match for all of them
		use this dtb if that's the case

stop booting / "best guess match"

?

[...]

> +#define QCOM_BOARD_ID_MTP		0x8
> +#define QCOM_BOARD_ID_DRAGONBOARD	0x10
> +#define QCOM_BOARD_ID_QRD		0x11
> +#define QCOM_BOARD_ID_HDK		0x1F
> +#define QCOM_BOARD_ID_ATP		0x21
> +#define QCOM_BOARD_ID_IDP		0x22
> +#define QCOM_BOARD_ID_SBC		0x24
> +#define QCOM_BOARD_ID_QXR		0x26
> +#define QCOM_BOARD_ID_CRD		0x28

Missing ADP/QCP/Ride (if they're separate)

Konrad

Re: [PATCH 1/2] dt-bindings: hwinfo: Introduce board-id

[Trilok Soni]

On 1/20/2024 3:20 AM, Amrit Anand wrote:
> From: Elliot Berman <quic_eberman@quicinc.com>
> 
> Device manufacturers frequently ship multiple boards or SKUs under a
> single software package. These software packages will ship multiple
> devicetree blobs and require some mechanism to pick the correct DTB for
> the board the software package was deployed. Introduce a common
> definition for adding board identifiers to device trees. board-id
> provides a mechanism for bootloaders to select the appropriate DTB which
> is vendor/OEM-agnostic.

Please extend CC list to more architectures? linux-arm-kernel, risc-v etc; since
the proposal below is not specific to ARM but any architecture is using the 
devicetree. 

-- 
---Trilok Soni

Re: [PATCH 2/2] dt-bindings: hwinfo: Add Qualcomm's board-id types

[kernel test robot]

Hi Amrit,

kernel test robot noticed the following build warnings:

[auto build test WARNING on robh/for-next]
[also build test WARNING on linus/master v6.7 next-20240119]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Amrit-Anand/dt-bindings-hwinfo-Introduce-board-id/20240120-192358
base:   https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git for-next
patch link:    https://lore.kernel.org/r/1705749649-4708-3-git-send-email-quic_amrianan%40quicinc.com
patch subject: [PATCH 2/2] dt-bindings: hwinfo: Add Qualcomm's board-id types
compiler: loongarch64-linux-gcc (GCC) 13.2.0
reproduce: (https://download.01.org/0day-ci/archive/20240121/202401210920.aPy2DJwj-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202401210920.aPy2DJwj-lkp@intel.com/

dtcheck warnings: (new ones prefixed by >>)
>> Documentation/devicetree/bindings/hwinfo/board-id.yaml:23:11: [error] string value is redundantly quoted with any quotes (quoted-strings)
   Documentation/devicetree/bindings/hwinfo/board-id.yaml:25:11: [error] string value is redundantly quoted with any quotes (quoted-strings)
>> Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml:70:4: [warning] wrong indentation: expected 2 but found 3 (indentation)

vim +70 Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml

    68	
    69	examples:
  > 70	   - |

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH 2/2] dt-bindings: hwinfo: Add Qualcomm's board-id types

[Amrit Anand]

On 1/20/2024 7:02 PM, Konrad Dybcio wrote:
> On 20.01.2024 12:20, Amrit Anand wrote:
>> Qualcomm based DT uses two or three different identifiers. The SoC
>> based idenfier which signifies chipset and the revision for those
>> chipsets. The board based identifier is used to distinguish different
>> boards (e.g. IDP, MTP) along with the different types of same boards.
>> The PMIC attached to the board can also be used as a identifier for
>> device tree.
>>
>> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
>> Signed-off-by: Amrit Anand <quic_amrianan@quicinc.com>
>> ---
>>   .../devicetree/bindings/hwinfo/qcom,board-id.yaml  | 86 ++++++++++++++++++++++
>>   include/dt-bindings/arm/qcom,ids.h                 | 68 +++++++++++++++--
>>   2 files changed, 146 insertions(+), 8 deletions(-)
>>   create mode 100644 Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml b/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
>> new file mode 100644
>> index 0000000..807f134
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
>> @@ -0,0 +1,86 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/hwinfo/qcom,board-id.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: QCOM Board Identifier for Devicetree Selection
>> +
>> +maintainers:
>> +  - Amrit Anand <quic_amrianan@quicinc.com>
>> +  - Elliot Berman <quic_eberman@quicinc.com>
>> +
>> +description: |
> The '|'s are unnecessary in both commits, IIRC they're used for
> preserving formatting which we don't really need for non-styled
> plaintext
Sure, will do.
>> +  Qualcomm uses two and sometimes three hardware identifiers to describe
>> +  its boards
>> +      - a SoC identifier is used to match chipsets (e.g. sm8550 vs sm8450)
>> +      - a board identifier is used to match board form factor (e.g. MTP, QRD,
>> +        ADP, CRD)
>> +      - a PMIC identifier is occasionally used when different PMICs are used
>> +        for a given board/SoC combination.
>> +  Each field and helper macros are defined at::
>> +      - include/dt-bindings/arm/qcom,ids.h
>> +
>> +  For example,
>> +    / {
>> +        #board-id-cells = <2>;
>> +        board-id = <456 0>, <457 0>, <10 0>;
>> +        board-id-types = "qcom,soc-id", "qcom,soc-id", "qcom,board-id";
>> +     }
>> +
>> +allOf:
>> +  - $ref: board-id.yaml#
>> +
>> +properties:
>> +  board-id:
>> +    minItems: 2
> I believe some older platforms match exclusively based on socid, so
> perhaps 1 would be okay as well.
>
> [...]

Ok, considering legacy targets we can make it 1.

But i think ideally it should always be recommended to have a board ID 
associated with a SoC ID, correct me if my understanding is wrong.

>> +examples:
>> +   - |
>> +     #include <dt-bindings/arm/qcom,ids.h>
>> +     / {
>> +         model = "Qualcomm Technologies, Inc. sc7280 IDP SKU1 platform";
>> +         compatible = "qcom,sc7280-idp", "google,senor", "qcom,sc7280";
>> +
>> +         #board-id-cells = <2>;
>> +         board-id = <QCOM_SOC_ID(SC7280) QCOM_SOC_REVISION(1)>,
>> +                    <QCOM_SOC_ID(SC7280) QCOM_SOC_REVISION(2)>,
>> +                    <QCOM_BOARD_ID(IDP, 1, 0) QCOM_BOARD_SUBTYPE(UFS, ANY, 1)>;
>> +         board-id-types = "qcom,soc-id",
>> +                          "qcom,soc-id",
>> +                          "qcom,board-id";
> So, would the matching here would be:
>
> loop over disctinct board-id-types
> 	check if there's at least 1 match for all of them
> 		use this dtb if that's the case
>
> stop booting / "best guess match"
>
> ?
>
> [...]

Yes, But the "if" checking would have preference in place.
The preference logic would look something like this,

First will check for SoC-ID, if we have an exact match for SoC-ID then 
will proceed for board-ID match. Otherwise the DT would be discarded.
Once (exact) board-ID found, will proceed for subtype , pmic and so on.
Exact match and best match logic is used. Parameters like SoC-ID, 
board-ID are required to be best matched. Other few fields follow best 
match logic and best of the DT can be picked.

>> +#define QCOM_BOARD_ID_MTP		0x8
>> +#define QCOM_BOARD_ID_DRAGONBOARD	0x10
>> +#define QCOM_BOARD_ID_QRD		0x11
>> +#define QCOM_BOARD_ID_HDK		0x1F
>> +#define QCOM_BOARD_ID_ATP		0x21
>> +#define QCOM_BOARD_ID_IDP		0x22
>> +#define QCOM_BOARD_ID_SBC		0x24
>> +#define QCOM_BOARD_ID_QXR		0x26
>> +#define QCOM_BOARD_ID_CRD		0x28
> Missing ADP/QCP/Ride (if they're separate)

Sure, will update. Would need to work with teams.

Thanks,
Amrit.

Re: [PATCH 1/2] dt-bindings: hwinfo: Introduce board-id

[Amrit Anand]

On 1/21/2024 12:40 AM, Trilok Soni wrote:
> On 1/20/2024 3:20 AM, Amrit Anand wrote:
>> From: Elliot Berman <quic_eberman@quicinc.com>
>>
>> Device manufacturers frequently ship multiple boards or SKUs under a
>> single software package. These software packages will ship multiple
>> devicetree blobs and require some mechanism to pick the correct DTB for
>> the board the software package was deployed. Introduce a common
>> definition for adding board identifiers to device trees. board-id
>> provides a mechanism for bootloaders to select the appropriate DTB which
>> is vendor/OEM-agnostic.
> Please extend CC list to more architectures? linux-arm-kernel, risc-v etc; since
> the proposal below is not specific to ARM but any architecture is using the
> devicetree.
Wouldn't devicetree@vger.kernel.org will have concern folks from all the 
architectures?
Please correct me.

Thanks,
Amrit.

Re: [PATCH 0/2] Add board-id support for multiple DT selection

[Elliot Berman]

+devicetree-spec

On 1/20/2024 5:04 AM, Konrad Dybcio wrote:
> On 20.01.2024 12:20, Amrit Anand wrote:
>> Device manufacturers frequently ship multiple boards or SKUs under a
>> single software package. These software packages will ship multiple
>> devicetree blobs and require some mechanism to pick the correct DTB for
>> the board the software package was deployed. Introduce a common
>> definition for adding board identifiers to device trees. board-id
>> provides a mechanism for bootloaders to select the appropriate DTB which
>> is vendor/OEM-agnostic.
> 
> Maybe it'd be a good idea to add it to the base spec!
> 
> https://github.com/devicetree-org/devicetree-specification
> 

I agree. Rob, what do you think?

Re: [PATCH 2/2] dt-bindings: hwinfo: Add Qualcomm's board-id types

[Elliot Berman]

On 1/22/2024 2:07 AM, Amrit Anand wrote:
> 
> On 1/20/2024 7:02 PM, Konrad Dybcio wrote:
>> On 20.01.2024 12:20, Amrit Anand wrote:
>>> Qualcomm based DT uses two or three different identifiers. The SoC
>>> based idenfier which signifies chipset and the revision for those
>>> chipsets. The board based identifier is used to distinguish different
>>> boards (e.g. IDP, MTP) along with the different types of same boards.
>>> The PMIC attached to the board can also be used as a identifier for
>>> device tree.
>>>
>>> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
>>> Signed-off-by: Amrit Anand <quic_amrianan@quicinc.com>
>>> ---
>>>   .../devicetree/bindings/hwinfo/qcom,board-id.yaml  | 86 ++++++++++++++++++++++
>>>   include/dt-bindings/arm/qcom,ids.h                 | 68 +++++++++++++++--
>>>   2 files changed, 146 insertions(+), 8 deletions(-)
>>>   create mode 100644 Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml b/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
>>> new file mode 100644
>>> index 0000000..807f134
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
>>> @@ -0,0 +1,86 @@
>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>> +%YAML 1.2
>>> +---
>>> +$id: http://devicetree.org/schemas/hwinfo/qcom,board-id.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> +
>>> +title: QCOM Board Identifier for Devicetree Selection
>>> +
>>> +maintainers:
>>> +  - Amrit Anand <quic_amrianan@quicinc.com>
>>> +  - Elliot Berman <quic_eberman@quicinc.com>
>>> +
>>> +description: |
>> The '|'s are unnecessary in both commits, IIRC they're used for
>> preserving formatting which we don't really need for non-styled
>> plaintext
> Sure, will do.
>>> +  Qualcomm uses two and sometimes three hardware identifiers to describe
>>> +  its boards
>>> +      - a SoC identifier is used to match chipsets (e.g. sm8550 vs sm8450)
>>> +      - a board identifier is used to match board form factor (e.g. MTP, QRD,
>>> +        ADP, CRD)
>>> +      - a PMIC identifier is occasionally used when different PMICs are used
>>> +        for a given board/SoC combination.
>>> +  Each field and helper macros are defined at::
>>> +      - include/dt-bindings/arm/qcom,ids.h
>>> +
>>> +  For example,
>>> +    / {
>>> +        #board-id-cells = <2>;
>>> +        board-id = <456 0>, <457 0>, <10 0>;
>>> +        board-id-types = "qcom,soc-id", "qcom,soc-id", "qcom,board-id";
>>> +     }
>>> +
>>> +allOf:
>>> +  - $ref: board-id.yaml#
>>> +
>>> +properties:
>>> +  board-id:
>>> +    minItems: 2
>> I believe some older platforms match exclusively based on socid, so
>> perhaps 1 would be okay as well.
>>
>> [...]
> 
> Ok, considering legacy targets we can make it 1.
> 
> But i think ideally it should always be recommended to have a board ID associated with a SoC ID, correct me if my understanding is wrong.
> 

There is no "legacy" support needed here: Qualcomm's bootloaders
need to be updated to adhere to the new proposed spec. I suppose
we need to consider whether we have targets that only need SoC to
differentiate?

>>> +examples:
>>> +   - |
>>> +     #include <dt-bindings/arm/qcom,ids.h>
>>> +     / {
>>> +         model = "Qualcomm Technologies, Inc. sc7280 IDP SKU1 platform";
>>> +         compatible = "qcom,sc7280-idp", "google,senor", "qcom,sc7280";
>>> +
>>> +         #board-id-cells = <2>;
>>> +         board-id = <QCOM_SOC_ID(SC7280) QCOM_SOC_REVISION(1)>,
>>> +                    <QCOM_SOC_ID(SC7280) QCOM_SOC_REVISION(2)>,
>>> +                    <QCOM_BOARD_ID(IDP, 1, 0) QCOM_BOARD_SUBTYPE(UFS, ANY, 1)>;
>>> +         board-id-types = "qcom,soc-id",
>>> +                          "qcom,soc-id",
>>> +                          "qcom,board-id";
>> So, would the matching here would be:
>>
>> loop over disctinct board-id-types
>>     check if there's at least 1 match for all of them
>>         use this dtb if that's the case
>>
>> stop booting / "best guess match"
>>
>> ?
>>
>> [...]
> 
> Yes, But the "if" checking would have preference in place.
> The preference logic would look something like this,
> 
> First will check for SoC-ID, if we have an exact match for SoC-ID then will proceed for board-ID match. Otherwise the DT would be discarded.
> Once (exact) board-ID found, will proceed for subtype , pmic and so on.
> Exact match and best match logic is used. Parameters like SoC-ID, board-ID are required to be best matched. Other few fields follow best match logic and best of the DT can be picked.
> 
>>> +#define QCOM_BOARD_ID_MTP        0x8
>>> +#define QCOM_BOARD_ID_DRAGONBOARD    0x10
>>> +#define QCOM_BOARD_ID_QRD        0x11
>>> +#define QCOM_BOARD_ID_HDK        0x1F
>>> +#define QCOM_BOARD_ID_ATP        0x21
>>> +#define QCOM_BOARD_ID_IDP        0x22
>>> +#define QCOM_BOARD_ID_SBC        0x24
>>> +#define QCOM_BOARD_ID_QXR        0x26
>>> +#define QCOM_BOARD_ID_CRD        0x28
>> Missing ADP/QCP/Ride (if they're separate)
> 
> Sure, will update. Would need to work with teams.

There are probably more boards that we aren't aware of.

Amrit, please add board IDs for all the boards that are
in kernel.org.

Re: [PATCH 2/2] dt-bindings: hwinfo: Add Qualcomm's board-id types

[Elliot Berman]

On 1/20/2024 3:20 AM, Amrit Anand wrote:
> Qualcomm based DT uses two or three different identifiers. The SoC
> based idenfier which signifies chipset and the revision for those
> chipsets. The board based identifier is used to distinguish different
> boards (e.g. IDP, MTP) along with the different types of same boards.
> The PMIC attached to the board can also be used as a identifier for
> device tree.
> 
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> Signed-off-by: Amrit Anand <quic_amrianan@quicinc.com>
> ---
>  .../devicetree/bindings/hwinfo/qcom,board-id.yaml  | 86 ++++++++++++++++++++++
>  include/dt-bindings/arm/qcom,ids.h                 | 68 +++++++++++++++--
>  2 files changed, 146 insertions(+), 8 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
> 
> diff --git a/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml b/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
> new file mode 100644
> index 0000000..807f134
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
> @@ -0,0 +1,86 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/hwinfo/qcom,board-id.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: QCOM Board Identifier for Devicetree Selection
> +
> +maintainers:
> +  - Amrit Anand <quic_amrianan@quicinc.com>
> +  - Elliot Berman <quic_eberman@quicinc.com>
> +
> +description: |
> +  Qualcomm uses two and sometimes three hardware identifiers to describe
> +  its boards
> +      - a SoC identifier is used to match chipsets (e.g. sm8550 vs sm8450)
> +      - a board identifier is used to match board form factor (e.g. MTP, QRD,
> +        ADP, CRD)
> +      - a PMIC identifier is occasionally used when different PMICs are used
> +        for a given board/SoC combination.
> +  Each field and helper macros are defined at::
> +      - include/dt-bindings/arm/qcom,ids.h
> +
> +  For example,
> +    / {
> +        #board-id-cells = <2>;
> +        board-id = <456 0>, <457 0>, <10 0>;
> +        board-id-types = "qcom,soc-id", "qcom,soc-id", "qcom,board-id";
> +     }
> +
> +allOf:
> +  - $ref: board-id.yaml#
> +

There's nothing to cause this binding to be selected.

Please add a select clause. I guess we can make it based off
whether the board's compatible contains "qcom,".

> +properties:
> +  board-id:
> +    minItems: 2
> +
> +  board-id-types:
> +    minItems: 2
> +    items:
> +      oneOf:
> +        - const: qcom,soc-id
> +          description: |
> +            Matches Qualcomm Technologies, Inc. boards with the specified SoC.
> +            2 integers are needed to describe a soc-id. The first integer is the
> +            SoC ID and the second integer is the SoC revision.
> +            qcom,soc-id = <soc-id  soc-revision>
> +        - const: qcom,board-id
> +          description: |
> +            Matches Qualcomm Technologies, Inc. boards with the specified board.
> +            2 integers are needed to describe a board-id. The first integer is the
> +            board ID. The second integer is the board-subtype.
> +            qcom,board-id = <board-id  board-subtype>
> +        - const: qcom,pmic-id
> +          description: |
> +            QUALCOMM boards can be atached to mutliple PMICs where slave-id (SID)
> +            indicates the address of the bus on which the PMIC is attached. It can be
> +            any number. The model for a PMIC indicates the PMIC name attached to bus
> +            described by SID along with  major and minor version. 2 integers are needed
> +            to describe qcom,pmic-id. The first integer is the slave-id and the second integer
> +            is the pmic model.
> +            qcom,pmic-id = <pmic-sid pmic-model>
> +
> +  '#board-id-cells':
> +    minimum: 2
> +
> +additionalProperties: true
> +
> +examples:
> +   - |
> +     #include <dt-bindings/arm/qcom,ids.h>
> +     / {
> +         model = "Qualcomm Technologies, Inc. sc7280 IDP SKU1 platform";
> +         compatible = "qcom,sc7280-idp", "google,senor", "qcom,sc7280";
> +
> +         #board-id-cells = <2>;
> +         board-id = <QCOM_SOC_ID(SC7280) QCOM_SOC_REVISION(1)>,
> +                    <QCOM_SOC_ID(SC7280) QCOM_SOC_REVISION(2)>,
> +                    <QCOM_BOARD_ID(IDP, 1, 0) QCOM_BOARD_SUBTYPE(UFS, ANY, 1)>;
> +         board-id-types = "qcom,soc-id",
> +                          "qcom,soc-id",
> +                          "qcom,board-id";
> +
> +         #address-cells = <2>;
> +         #size-cells = <2>;
> +      };
> diff --git a/include/dt-bindings/arm/qcom,ids.h b/include/dt-bindings/arm/qcom,ids.h
> index f724834..c4cd440 100644
> --- a/include/dt-bindings/arm/qcom,ids.h
> +++ b/include/dt-bindings/arm/qcom,ids.h
> @@ -8,9 +8,12 @@
>  #define _DT_BINDINGS_ARM_QCOM_IDS_H
>  
>  /*
> - * The MSM chipset and hardware revision used by Qualcomm bootloaders, DTS for
> - * older chipsets (qcom,msm-id) and in socinfo driver:
> + * The MSM chipset ID used by Qualcomm bootloaders, DTS for
> + * older chipsets (soc-id) and in socinfo driver:
>   */
> +
> +#define QCOM_SOC_ID(a)  ((QCOM_ID_##a) && 0xffff)
> +
>  #define QCOM_ID_MSM8260			70
>  #define QCOM_ID_MSM8660			71
>  #define QCOM_ID_APQ8060			86
> @@ -266,16 +269,65 @@
>  #define QCOM_ID_IPQ5302			595
>  #define QCOM_ID_IPQ5300			624
>  
> + /* The SOC revision used by Qualcomm bootloaders (soc-revision) */
> +
> +#define QCOM_SOC_REVISION(a)		(a & 0xff)
> +
>  /*
>   * The board type and revision information, used by Qualcomm bootloaders and
> - * DTS for older chipsets (qcom,board-id):
> + * DTS for older chipsets (board-id)
>   */
> +
>  #define QCOM_BOARD_ID(a, major, minor) \
> -	(((major & 0xff) << 16) | ((minor & 0xff) << 8) | QCOM_BOARD_ID_##a)
> +	(((major & 0xff) << 16) | ((minor & 0xff) << 8) | ((QCOM_BOARD_ID_##a) & 0xff))
> +
> +#define QCOM_BOARD_ID_MTP		0x8
> +#define QCOM_BOARD_ID_DRAGONBOARD	0x10
> +#define QCOM_BOARD_ID_QRD		0x11
> +#define QCOM_BOARD_ID_HDK		0x1F
> +#define QCOM_BOARD_ID_ATP		0x21
> +#define QCOM_BOARD_ID_IDP		0x22
> +#define QCOM_BOARD_ID_SBC		0x24
> +#define QCOM_BOARD_ID_QXR		0x26
> +#define QCOM_BOARD_ID_CRD		0x28
> +
> +/*
> + * The platform subtype is used by Qualcomm bootloaders and
> + * DTS (board-subtype)
> + */
> +#define QCOM_BOARD_SUBTYPE(a, b, SUBTYPE) \
> +	(((QCOM_BOARD_BOOT_##a & 0xf) << 16) | ((QCOM_BOARD_DDRTYPE_##b & 0x7) << 8) | \
> +	(SUBTYPE & 0xff))
> +
> +/* Board DDR Type where each value indicates higher limit */
> +#define QCOM_BOARD_DDRTYPE_ANY		0x0
> +#define QCOM_BOARD_DDRTYPE_128M		0x1
> +#define QCOM_BOARD_DDRTYPE_256M		0x2
> +#define QCOM_BOARD_DDRTYPE_512M		0x3
> +#define QCOM_BOARD_DDRTYPE_1024M	0x4
> +#define QCOM_BOARD_DDRTYPE_2048M	0x5
> +#define QCOM_BOARD_DDRTYPE_3072M	0x6
> +#define QCOM_BOARD_DDRTYPE_4096M	0x7
> +
> +/* Board Boot Device Type */
> +#define QCOM_BOARD_BOOT_EMMC		0x0
> +#define QCOM_BOARD_BOOT_UFS		0x1
> +#define QCOM_BOARD_BOOT_NAND		0x2
> +#define QCOM_BOARD_BOOT_OTHER		0x3
> +
> +/*
> + * The PMIC slave id is used by Qualcomm bootloaders to
> + * indicates which PMIC is attached (pmic-sid)
> + */
> +
> +#define QCOM_PMIC_SID(a)		(a & 0xff)
> +
> +/*
> + * The PMIC ID is used by Qualcomm bootloaders to describe the ID
> + * of PMIC attached to bus described by SID (pmic-model)
> + */
>  
> -#define QCOM_BOARD_ID_MTP			8
> -#define QCOM_BOARD_ID_DRAGONBOARD		10
> -#define QCOM_BOARD_ID_QRD			11
> -#define QCOM_BOARD_ID_SBC			24
> +#define QCOM_PMIC_MODEL(ID, major, minor) \
> +	(((major & 0xff) << 16) | ((minor & 0xff) << 8) | (ID & 0xff))
>  
>  #endif /* _DT_BINDINGS_ARM_QCOM_IDS_H */

Re: [PATCH 2/2] dt-bindings: hwinfo: Add Qualcomm's board-id types

[Dmitry Baryshkov]

On Mon, 22 Jan 2024 at 20:46, Elliot Berman <quic_eberman@quicinc.com> wrote:
>
>
>
> On 1/22/2024 2:07 AM, Amrit Anand wrote:
> >
> > On 1/20/2024 7:02 PM, Konrad Dybcio wrote:
> >> On 20.01.2024 12:20, Amrit Anand wrote:
> >>> Qualcomm based DT uses two or three different identifiers. The SoC
> >>> based idenfier which signifies chipset and the revision for those
> >>> chipsets. The board based identifier is used to distinguish different
> >>> boards (e.g. IDP, MTP) along with the different types of same boards.
> >>> The PMIC attached to the board can also be used as a identifier for
> >>> device tree.
> >>>
> >>> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> >>> Signed-off-by: Amrit Anand <quic_amrianan@quicinc.com>
> >>> ---
> >>>   .../devicetree/bindings/hwinfo/qcom,board-id.yaml  | 86 ++++++++++++++++++++++
> >>>   include/dt-bindings/arm/qcom,ids.h                 | 68 +++++++++++++++--
> >>>   2 files changed, 146 insertions(+), 8 deletions(-)
> >>>   create mode 100644 Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml b/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
> >>> new file mode 100644
> >>> index 0000000..807f134
> >>> --- /dev/null
> >>> +++ b/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
> >>> @@ -0,0 +1,86 @@
> >>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> >>> +%YAML 1.2
> >>> +---
> >>> +$id: http://devicetree.org/schemas/hwinfo/qcom,board-id.yaml#
> >>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >>> +
> >>> +title: QCOM Board Identifier for Devicetree Selection
> >>> +
> >>> +maintainers:
> >>> +  - Amrit Anand <quic_amrianan@quicinc.com>
> >>> +  - Elliot Berman <quic_eberman@quicinc.com>
> >>> +
> >>> +description: |
> >> The '|'s are unnecessary in both commits, IIRC they're used for
> >> preserving formatting which we don't really need for non-styled
> >> plaintext
> > Sure, will do.
> >>> +  Qualcomm uses two and sometimes three hardware identifiers to describe
> >>> +  its boards
> >>> +      - a SoC identifier is used to match chipsets (e.g. sm8550 vs sm8450)
> >>> +      - a board identifier is used to match board form factor (e.g. MTP, QRD,
> >>> +        ADP, CRD)
> >>> +      - a PMIC identifier is occasionally used when different PMICs are used
> >>> +        for a given board/SoC combination.
> >>> +  Each field and helper macros are defined at::
> >>> +      - include/dt-bindings/arm/qcom,ids.h
> >>> +
> >>> +  For example,
> >>> +    / {
> >>> +        #board-id-cells = <2>;
> >>> +        board-id = <456 0>, <457 0>, <10 0>;
> >>> +        board-id-types = "qcom,soc-id", "qcom,soc-id", "qcom,board-id";
> >>> +     }
> >>> +
> >>> +allOf:
> >>> +  - $ref: board-id.yaml#
> >>> +
> >>> +properties:
> >>> +  board-id:
> >>> +    minItems: 2
> >> I believe some older platforms match exclusively based on socid, so
> >> perhaps 1 would be okay as well.
> >>
> >> [...]
> >
> > Ok, considering legacy targets we can make it 1.
> >
> > But i think ideally it should always be recommended to have a board ID associated with a SoC ID, correct me if my understanding is wrong.
> >
>
> There is no "legacy" support needed here: Qualcomm's bootloaders
> need to be updated to adhere to the new proposed spec. I suppose
> we need to consider whether we have targets that only need SoC to
> differentiate?

What is the chance of updating the bootloader for the N year device?


-- 
With best wishes
Dmitry

Re: [PATCH 1/2] dt-bindings: hwinfo: Introduce board-id

[Krzysztof Kozlowski]

On 22/01/2024 11:10, Amrit Anand wrote:
> 
> On 1/21/2024 12:40 AM, Trilok Soni wrote:
>> On 1/20/2024 3:20 AM, Amrit Anand wrote:
>>> From: Elliot Berman <quic_eberman@quicinc.com>
>>>
>>> Device manufacturers frequently ship multiple boards or SKUs under a
>>> single software package. These software packages will ship multiple
>>> devicetree blobs and require some mechanism to pick the correct DTB for
>>> the board the software package was deployed. Introduce a common
>>> definition for adding board identifiers to device trees. board-id
>>> provides a mechanism for bootloaders to select the appropriate DTB which
>>> is vendor/OEM-agnostic.
>> Please extend CC list to more architectures? linux-arm-kernel, risc-v etc; since
>> the proposal below is not specific to ARM but any architecture is using the
>> devicetree.
> Wouldn't devicetree@vger.kernel.org will have concern folks from all the 
> architectures?
> Please correct me.

No.

Best regards,
Krzysztof

Re: [PATCH 1/2] dt-bindings: hwinfo: Introduce board-id

[Krzysztof Kozlowski]

On 20/01/2024 12:20, Amrit Anand wrote:
> From: Elliot Berman <quic_eberman@quicinc.com>
> 



> 
> How is this better than Qualcomm's qcom,msm-id/qcom,board-id?
> -------------------------------------------------------------
> The selection process for devicetrees was Qualcomm-specific and not
> useful for other devices and bootloaders that were not developed by
> Qualcomm because a complex algorithm was used to implement. Board-ids
> provide a matching solution that can be implemented by bootloaders
> without introducing vendor-specific code. Qualcomm uses three
> devicetree properties: msm-id (interchangeably: soc-id), board-id, and
> pmic-id.  This does not scale well for use casese which use identifiers,
> for example, to distinguish between a display panel. For a display
> panel, an approach could be to add a new property: display-id,
> but now	bootloaders need to be updated to also read this property. We
> want to	avoid requiring to update bootloaders with new hardware

Some mis-indentation in two lines above.

> identifiers: a bootloader need only recognize the identifiers it can
> handle.
> 
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> Signed-off-by: Amrit Anand <quic_amrianan@quicinc.com>
> ---
>  .../devicetree/bindings/hwinfo/board-id.yaml       | 53 ++++++++++++++++++++++
>  1 file changed, 53 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/hwinfo/board-id.yaml
> 
> diff --git a/Documentation/devicetree/bindings/hwinfo/board-id.yaml b/Documentation/devicetree/bindings/hwinfo/board-id.yaml

I think we should add it to dtschema, because bootloaders are using these.

> new file mode 100644
> index 0000000..82d5ff7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwinfo/board-id.yaml
> @@ -0,0 +1,53 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/hwinfo/board-id.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Board Identifier for Devicetree Selection
> +
> +maintainers:
> +  - Amrit Anand <quic_amrianan@quicinc.com>
> +  - Elliot Berman <quic_eberman@quicinc.com>
> +
> +description: |

Do not need '|' unless you need to preserve formatting.

> +  Device manufacturers frequently ship multiple boards under a single
> +  software package. These software packages will ship multiple devicetree
> +  blobs and require some mechanism to pick the correct DTB for the board
> +  the software package was deployed. board-id provides a mechanism for
> +  bootloaders to select the appropriate DTB which is vendor/OEM-agnostic.
> +
> +select:
> +  anyOf:
> +    - required:
> +        - 'board-id'
> +    - required:
> +        - 'board-id-types'
> +    - required:
> +        - '#board-id-cells'

I don't fully get why do you need this select. Isn't the schema selected
by nodename? Or maybe it is for the final required: but then this could
be just set of dependencies.

> +
> +properties:
> +  $nodename:
> +    const: "/"

Blank line.

> +  board-id:
> +    $ref: /schemas/types.yaml#/definitions/uint32-matrix
> +    description: |

Do not need '|' unless you need to preserve formatting.

> +      A list of identifiers that can be used to match with this devicetree.

s/devicetree/Devicetree/ ?

> +      The interpretatation of each cell can be matched with the

Typo: interpretation

> +      board-id-type at the same index.
> +
> +  board-id-types:
> +    $ref: /schemas/types.yaml#/definitions/non-unique-string-array
> +    description:
> +      Defines the type of each cell, indicating to the DeviceTree selection

s/DeviceTree/Devicetree/ ?


> +      mechanism how to parse the board-id.
> +
> +  '#board-id-cells':

 What are the cells for?

> +    minimum: 1
> +
> +required:
> +  - board-id
> +  - board-id-types
> +  - '#board-id-cells'


> +
> +additionalProperties: true

Best regards,
Krzysztof

Re: [PATCH 1/2] dt-bindings: hwinfo: Introduce board-id

[Conor Dooley]

[-- Attachment #1: Type: text/plain, Size: 1363 bytes --]

On Tue, Jan 23, 2024 at 12:50:07PM +0100, Krzysztof Kozlowski wrote:
> On 22/01/2024 11:10, Amrit Anand wrote:
> > 
> > On 1/21/2024 12:40 AM, Trilok Soni wrote:
> >> On 1/20/2024 3:20 AM, Amrit Anand wrote:
> >>> From: Elliot Berman <quic_eberman@quicinc.com>
> >>>
> >>> Device manufacturers frequently ship multiple boards or SKUs under a
> >>> single software package. These software packages will ship multiple
> >>> devicetree blobs and require some mechanism to pick the correct DTB for
> >>> the board the software package was deployed. Introduce a common
> >>> definition for adding board identifiers to device trees. board-id
> >>> provides a mechanism for bootloaders to select the appropriate DTB which
> >>> is vendor/OEM-agnostic.
> >> Please extend CC list to more architectures? linux-arm-kernel, risc-v etc; since
> >> the proposal below is not specific to ARM but any architecture is using the
> >> devicetree.
> > Wouldn't devicetree@vger.kernel.org will have concern folks from all the 
> > architectures?
> > Please correct me.
> 
> No.

The chromium guys should get a CC on future versions of this stuff,
since they like doing wacky things with compatible strings in their
bootloader and this problem is one they also face. Doug Anderson and the
mediatek chromebook folks would be a good start.

Thanks,
Conor.

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Re: [PATCH 1/2] dt-bindings: hwinfo: Introduce board-id

[Elliot Berman]

On 1/23/2024 9:18 AM, Conor Dooley wrote:
> On Tue, Jan 23, 2024 at 12:50:07PM +0100, Krzysztof Kozlowski wrote:
>> On 22/01/2024 11:10, Amrit Anand wrote:
>>>
>>> On 1/21/2024 12:40 AM, Trilok Soni wrote:
>>>> On 1/20/2024 3:20 AM, Amrit Anand wrote:
>>>>> From: Elliot Berman <quic_eberman@quicinc.com>
>>>>>
>>>>> Device manufacturers frequently ship multiple boards or SKUs under a
>>>>> single software package. These software packages will ship multiple
>>>>> devicetree blobs and require some mechanism to pick the correct DTB for
>>>>> the board the software package was deployed. Introduce a common
>>>>> definition for adding board identifiers to device trees. board-id
>>>>> provides a mechanism for bootloaders to select the appropriate DTB which
>>>>> is vendor/OEM-agnostic.
>>>> Please extend CC list to more architectures? linux-arm-kernel, risc-v etc; since
>>>> the proposal below is not specific to ARM but any architecture is using the
>>>> devicetree.
>>> Wouldn't devicetree@vger.kernel.org will have concern folks from all the 
>>> architectures?
>>> Please correct me.
>>
>> No.
> 
> The chromium guys should get a CC on future versions of this stuff,
> since they like doing wacky things with compatible strings in their
> bootloader and this problem is one they also face. Doug Anderson and the
> mediatek chromebook folks would be a good start.
> 

Please CC Peter Griffin from Linaro as he helped restart this 
discussion at Plumbers.

Peter Griffin <peter.griffin@linaro.org>

Also, for the oneplus boards:
Caleb Connolly <caleb.connolly@linaro.org>

Re: [PATCH 1/2] dt-bindings: hwinfo: Introduce board-id

[Trilok Soni]

On 1/23/2024 10:51 AM, Elliot Berman wrote:
> 
> 
> On 1/23/2024 9:18 AM, Conor Dooley wrote:
>> On Tue, Jan 23, 2024 at 12:50:07PM +0100, Krzysztof Kozlowski wrote:
>>> On 22/01/2024 11:10, Amrit Anand wrote:
>>>>
>>>> On 1/21/2024 12:40 AM, Trilok Soni wrote:
>>>>> On 1/20/2024 3:20 AM, Amrit Anand wrote:
>>>>>> From: Elliot Berman <quic_eberman@quicinc.com>
>>>>>>
>>>>>> Device manufacturers frequently ship multiple boards or SKUs under a
>>>>>> single software package. These software packages will ship multiple
>>>>>> devicetree blobs and require some mechanism to pick the correct DTB for
>>>>>> the board the software package was deployed. Introduce a common
>>>>>> definition for adding board identifiers to device trees. board-id
>>>>>> provides a mechanism for bootloaders to select the appropriate DTB which
>>>>>> is vendor/OEM-agnostic.
>>>>> Please extend CC list to more architectures? linux-arm-kernel, risc-v etc; since
>>>>> the proposal below is not specific to ARM but any architecture is using the
>>>>> devicetree.
>>>> Wouldn't devicetree@vger.kernel.org will have concern folks from all the 
>>>> architectures?
>>>> Please correct me.
>>>
>>> No.
>>
>> The chromium guys should get a CC on future versions of this stuff,
>> since they like doing wacky things with compatible strings in their
>> bootloader and this problem is one they also face. Doug Anderson and the
>> mediatek chromebook folks would be a good start.
>>
> 
> Please CC Peter Griffin from Linaro as he helped restart this 
> discussion at Plumbers.
> 
> Peter Griffin <peter.griffin@linaro.org>
> 
> Also, for the oneplus boards:
> Caleb Connolly <caleb.connolly@linaro.org>

Thank you everyone. Amrit - please take care of above comments
when you post next revision and as suggested please add other
architecture mailing lists using the devicetree. Thank you. 

-- 
---Trilok Soni

Re: [PATCH 1/2] dt-bindings: hwinfo: Introduce board-id

[Amrit Anand]

On 1/23/2024 5:39 PM, Krzysztof Kozlowski wrote:
> On 20/01/2024 12:20, Amrit Anand wrote:
>> From: Elliot Berman <quic_eberman@quicinc.com>
>>
>
>
>> How is this better than Qualcomm's qcom,msm-id/qcom,board-id?
>> -------------------------------------------------------------
>> The selection process for devicetrees was Qualcomm-specific and not
>> useful for other devices and bootloaders that were not developed by
>> Qualcomm because a complex algorithm was used to implement. Board-ids
>> provide a matching solution that can be implemented by bootloaders
>> without introducing vendor-specific code. Qualcomm uses three
>> devicetree properties: msm-id (interchangeably: soc-id), board-id, and
>> pmic-id.  This does not scale well for use casese which use identifiers,
>> for example, to distinguish between a display panel. For a display
>> panel, an approach could be to add a new property: display-id,
>> but now	bootloaders need to be updated to also read this property. We
>> want to	avoid requiring to update bootloaders with new hardware
> Some mis-indentation in two lines above.
Sure will take care of this.
>
>> identifiers: a bootloader need only recognize the identifiers it can
>> handle.
>>
>> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
>> Signed-off-by: Amrit Anand <quic_amrianan@quicinc.com>
>> ---
>>   .../devicetree/bindings/hwinfo/board-id.yaml       | 53 ++++++++++++++++++++++
>>   1 file changed, 53 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/hwinfo/board-id.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/hwinfo/board-id.yaml b/Documentation/devicetree/bindings/hwinfo/board-id.yaml
> I think we should add it to dtschema, because bootloaders are using these.
Do you want us to move this file completely to the below mentioned repo 
and under which directory?
https://github.com/devicetree-org/dt-schema

>
>> new file mode 100644
>> index 0000000..82d5ff7
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/hwinfo/board-id.yaml
>> @@ -0,0 +1,53 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/hwinfo/board-id.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Board Identifier for Devicetree Selection
>> +
>> +maintainers:
>> +  - Amrit Anand <quic_amrianan@quicinc.com>
>> +  - Elliot Berman <quic_eberman@quicinc.com>
>> +
>> +description: |
> Do not need '|' unless you need to preserve formatting.
Will drop it.
>
>> +  Device manufacturers frequently ship multiple boards under a single
>> +  software package. These software packages will ship multiple devicetree
>> +  blobs and require some mechanism to pick the correct DTB for the board
>> +  the software package was deployed. board-id provides a mechanism for
>> +  bootloaders to select the appropriate DTB which is vendor/OEM-agnostic.
>> +
>> +select:
>> +  anyOf:
>> +    - required:
>> +        - 'board-id'
>> +    - required:
>> +        - 'board-id-types'
>> +    - required:
>> +        - '#board-id-cells'
> I don't fully get why do you need this select. Isn't the schema selected
> by nodename? Or maybe it is for the final required: but then this could
> be just set of dependencies.
The nodename here would be "/". So it will be applied to all the DTs, right?
Here, we wanted this to apply only if the above mentioned properties are 
present.
Do you suggest moving this to qcom,board-id.yaml and the required: as well.
So that vendor specific yaml could be applied?
>> +
>> +properties:
>> +  $nodename:
>> +    const: "/"
> Blank line.
Will add it.
>> +  board-id:
>> +    $ref: /schemas/types.yaml#/definitions/uint32-matrix
>> +    description: |
> Do not need '|' unless you need to preserve formatting.
Ack
>> +      A list of identifiers that can be used to match with this devicetree.
> s/devicetree/Devicetree/ ?
Will update
>> +      The interpretatation of each cell can be matched with the
> Typo: interpretation
Will update
>> +      board-id-type at the same index.
>> +
>> +  board-id-types:
>> +    $ref: /schemas/types.yaml#/definitions/non-unique-string-array
>> +    description:
>> +      Defines the type of each cell, indicating to the DeviceTree selection
> s/DeviceTree/Devicetree/ ?
Will update
>
>> +      mechanism how to parse the board-id.
>> +
>> +  '#board-id-cells':
>   What are the cells for?
Bootloader will use this to check the number of entries in a tuple of 
board-id.
Vendors can have different logic in bootloader to specify the number
So wanted to make it flexible.

Thanks,
Amrit.

Re: [PATCH 1/2] dt-bindings: hwinfo: Introduce board-id

[Amrit Anand]

On 1/24/2024 1:35 AM, Trilok Soni wrote:
> On 1/23/2024 10:51 AM, Elliot Berman wrote:
>>
>> On 1/23/2024 9:18 AM, Conor Dooley wrote:
>>> On Tue, Jan 23, 2024 at 12:50:07PM +0100, Krzysztof Kozlowski wrote:
>>>> On 22/01/2024 11:10, Amrit Anand wrote:
>>>>> On 1/21/2024 12:40 AM, Trilok Soni wrote:
>>>>>> On 1/20/2024 3:20 AM, Amrit Anand wrote:
>>>>>>> From: Elliot Berman <quic_eberman@quicinc.com>
>>>>>>>
>>>>>>> Device manufacturers frequently ship multiple boards or SKUs under a
>>>>>>> single software package. These software packages will ship multiple
>>>>>>> devicetree blobs and require some mechanism to pick the correct DTB for
>>>>>>> the board the software package was deployed. Introduce a common
>>>>>>> definition for adding board identifiers to device trees. board-id
>>>>>>> provides a mechanism for bootloaders to select the appropriate DTB which
>>>>>>> is vendor/OEM-agnostic.
>>>>>> Please extend CC list to more architectures? linux-arm-kernel, risc-v etc; since
>>>>>> the proposal below is not specific to ARM but any architecture is using the
>>>>>> devicetree.
>>>>> Wouldn't devicetree@vger.kernel.org will have concern folks from all the
>>>>> architectures?
>>>>> Please correct me.
>>>> No.
>>> The chromium guys should get a CC on future versions of this stuff,
>>> since they like doing wacky things with compatible strings in their
>>> bootloader and this problem is one they also face. Doug Anderson and the
>>> mediatek chromebook folks would be a good start.
>>>
>> Please CC Peter Griffin from Linaro as he helped restart this
>> discussion at Plumbers.
>>
>> Peter Griffin <peter.griffin@linaro.org>
>>
>> Also, for the oneplus boards:
>> Caleb Connolly <caleb.connolly@linaro.org>
> Thank you everyone. Amrit - please take care of above comments
> when you post next revision and as suggested please add other
> architecture mailing lists using the devicetree. Thank you.
Sure, will keep this in mind when sending next version. Thanks for 
pointing out.

Thanks,
Amrit.

Re: [PATCH 2/2] dt-bindings: hwinfo: Add Qualcomm's board-id types

[Amrit Anand]

On 1/22/2024 11:40 PM, Elliot Berman wrote:
>
> On 1/22/2024 2:07 AM, Amrit Anand wrote:
>> On 1/20/2024 7:02 PM, Konrad Dybcio wrote:
>>> On 20.01.2024 12:20, Amrit Anand wrote:
>>>> Qualcomm based DT uses two or three different identifiers. The SoC
>>>> based idenfier which signifies chipset and the revision for those
>>>> chipsets. The board based identifier is used to distinguish different
>>>> boards (e.g. IDP, MTP) along with the different types of same boards.
>>>> The PMIC attached to the board can also be used as a identifier for
>>>> device tree.
>>>>
>>>> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
>>>> Signed-off-by: Amrit Anand <quic_amrianan@quicinc.com>
>>>> ---
>>>>    .../devicetree/bindings/hwinfo/qcom,board-id.yaml  | 86 ++++++++++++++++++++++
>>>>    include/dt-bindings/arm/qcom,ids.h                 | 68 +++++++++++++++--
>>>>    2 files changed, 146 insertions(+), 8 deletions(-)
>>>>    create mode 100644 Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml b/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
>>>> new file mode 100644
>>>> index 0000000..807f134
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
>>>> @@ -0,0 +1,86 @@
>>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>>> +%YAML 1.2
>>>> +---
>>>> +$id: http://devicetree.org/schemas/hwinfo/qcom,board-id.yaml#
>>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>>> +
>>>> +title: QCOM Board Identifier for Devicetree Selection
>>>> +
>>>> +maintainers:
>>>> +  - Amrit Anand <quic_amrianan@quicinc.com>
>>>> +  - Elliot Berman <quic_eberman@quicinc.com>
>>>> +
>>>> +description: |
>>> The '|'s are unnecessary in both commits, IIRC they're used for
>>> preserving formatting which we don't really need for non-styled
>>> plaintext
>> Sure, will do.
>>>> +  Qualcomm uses two and sometimes three hardware identifiers to describe
>>>> +  its boards
>>>> +      - a SoC identifier is used to match chipsets (e.g. sm8550 vs sm8450)
>>>> +      - a board identifier is used to match board form factor (e.g. MTP, QRD,
>>>> +        ADP, CRD)
>>>> +      - a PMIC identifier is occasionally used when different PMICs are used
>>>> +        for a given board/SoC combination.
>>>> +  Each field and helper macros are defined at::
>>>> +      - include/dt-bindings/arm/qcom,ids.h
>>>> +
>>>> +  For example,
>>>> +    / {
>>>> +        #board-id-cells = <2>;
>>>> +        board-id = <456 0>, <457 0>, <10 0>;
>>>> +        board-id-types = "qcom,soc-id", "qcom,soc-id", "qcom,board-id";
>>>> +     }
>>>> +
>>>> +allOf:
>>>> +  - $ref: board-id.yaml#
>>>> +
>>>> +properties:
>>>> +  board-id:
>>>> +    minItems: 2
>>> I believe some older platforms match exclusively based on socid, so
>>> perhaps 1 would be okay as well.
>>>
>>> [...]
>> Ok, considering legacy targets we can make it 1.
>>
>> But i think ideally it should always be recommended to have a board ID associated with a SoC ID, correct me if my understanding is wrong.
>>
> There is no "legacy" support needed here: Qualcomm's bootloaders
> need to be updated to adhere to the new proposed spec. I suppose
> we need to consider whether we have targets that only need SoC to
> differentiate?
>
>>>> +examples:
>>>> +   - |
>>>> +     #include <dt-bindings/arm/qcom,ids.h>
>>>> +     / {
>>>> +         model = "Qualcomm Technologies, Inc. sc7280 IDP SKU1 platform";
>>>> +         compatible = "qcom,sc7280-idp", "google,senor", "qcom,sc7280";
>>>> +
>>>> +         #board-id-cells = <2>;
>>>> +         board-id = <QCOM_SOC_ID(SC7280) QCOM_SOC_REVISION(1)>,
>>>> +                    <QCOM_SOC_ID(SC7280) QCOM_SOC_REVISION(2)>,
>>>> +                    <QCOM_BOARD_ID(IDP, 1, 0) QCOM_BOARD_SUBTYPE(UFS, ANY, 1)>;
>>>> +         board-id-types = "qcom,soc-id",
>>>> +                          "qcom,soc-id",
>>>> +                          "qcom,board-id";
>>> So, would the matching here would be:
>>>
>>> loop over disctinct board-id-types
>>>      check if there's at least 1 match for all of them
>>>          use this dtb if that's the case
>>>
>>> stop booting / "best guess match"
>>>
>>> ?
>>>
>>> [...]
>> Yes, But the "if" checking would have preference in place.
>> The preference logic would look something like this,
>>
>> First will check for SoC-ID, if we have an exact match for SoC-ID then will proceed for board-ID match. Otherwise the DT would be discarded.
>> Once (exact) board-ID found, will proceed for subtype , pmic and so on.
>> Exact match and best match logic is used. Parameters like SoC-ID, board-ID are required to be best matched. Other few fields follow best match logic and best of the DT can be picked.
>>
>>>> +#define QCOM_BOARD_ID_MTP        0x8
>>>> +#define QCOM_BOARD_ID_DRAGONBOARD    0x10
>>>> +#define QCOM_BOARD_ID_QRD        0x11
>>>> +#define QCOM_BOARD_ID_HDK        0x1F
>>>> +#define QCOM_BOARD_ID_ATP        0x21
>>>> +#define QCOM_BOARD_ID_IDP        0x22
>>>> +#define QCOM_BOARD_ID_SBC        0x24
>>>> +#define QCOM_BOARD_ID_QXR        0x26
>>>> +#define QCOM_BOARD_ID_CRD        0x28
>>> Missing ADP/QCP/Ride (if they're separate)
>> Sure, will update. Would need to work with teams.
> There are probably more boards that we aren't aware of.
>
> Amrit, please add board IDs for all the boards that are
> in kernel.org.

Sure, will do that.

Thanks,
Amrit

Re: [PATCH 0/2] Add board-id support for multiple DT selection

[Rob Herring]

On Sat, Jan 20, 2024 at 04:50:47PM +0530, Amrit Anand wrote:
> Device manufacturers frequently ship multiple boards or SKUs under a
> single software package. These software packages will ship multiple
> devicetree blobs and require some mechanism to pick the correct DTB for
> the board the software package was deployed. Introduce a common
> definition for adding board identifiers to device trees. board-id
> provides a mechanism for bootloaders to select the appropriate DTB which
> is vendor/OEM-agnostic.

Show me a 2nd user. Or does vendor/OEM-agnostic just mean vendors of 
QCom devices? Multiple SoC families using this would help your case. I'm 
not inclined to take it into the DTSpec without that.

> 
> Isn't that what the compatible property is for?
> -----------------------------------------------
> The compatible property can be used for board matching, but requires
> bootloaders and/or firmware to maintain a database of possible strings
> to match against or have complex compatible string matching. Compatible
> string matching becomes complicated when there are multiple versions of
> board: the device tree selector should recognize a DTB that cares to
> distinguish between v1/v2 and a DTB that doesn't make the distinction.
> An eeprom either needs to store the compatible strings that could match
> against the board or the bootloader needs to have vendor-specific
> decoding logic for the compatible string. Neither increasing eeprom
> storage nor adding vendor-specific decoding logic is desirable.

You could hash the compatible strings if it was just a size issue.

> The solution proposed here is simpler to implement and doesn't require
> updating firmware or bootloader for every new board.
> 
> How is this better than Qualcomm's qcom,msm-id/qcom,board-id?
> -------------------------------------------------------------
> The selection process for devicetrees was Qualcomm-specific and not
> useful for other devices and bootloaders that were not developed by
> Qualcomm because a complex algorithm was used to implement. Board-ids
> provide a matching solution that can be implemented by bootloaders
> without introducing vendor-specific code. Qualcomm uses three
> devicetree properties: msm-id (interchangeably: soc-id), board-id, and
> pmic-id.  This does not scale well for use casese which use identifiers,
> for example, to distinguish between a display panel. For a display
> panel, an approach could be to add a new property: display-id, but now
> bootloaders need to be updated to also read this property. We want to
> avoid requiring to update bootloaders with new hardware identifiers: a
> bootloader need only recognize the identifiers it can handle.

So the id list will be always expanding list for every last component 
that is 2nd sourced? The ChromeOS folks are also trying to solve that 
problem.

There's a similar issue for EFI boot with how to select an OS installed 
DTB[1]. You might not care now, but users may later on (like we have 
already with QCom devices with fixed bootloaders). If you do this 
board-id route, then no doubt that compatible values won't be specific 
enough or have suitable fallbacks to be used. Then EFI boot can't use 
compatible either and needs to use this QCom specific logic. It may be a 
common property name, but all the types you defined are QCom specific 
and the matching logic is pretty much undocumented. I'm not saying we 
have to use compatible. There wasn't even agreement to use it for EFI 
boot case. This does need to work for multiple vendors and multiple boot 
scenarios.

Rob

[1] https://lore.kernel.org/u-boot/20231114232012.GD6601@bill-the-cat/#r

Re: [PATCH 1/2] dt-bindings: hwinfo: Introduce board-id

[Rob Herring]

On Sat, Jan 20, 2024 at 04:50:48PM +0530, Amrit Anand wrote:
> From: Elliot Berman <quic_eberman@quicinc.com>
> 
> Device manufacturers frequently ship multiple boards or SKUs under a
> single software package. These software packages will ship multiple
> devicetree blobs and require some mechanism to pick the correct DTB for
> the board the software package was deployed. Introduce a common
> definition for adding board identifiers to device trees. board-id
> provides a mechanism for bootloaders to select the appropriate DTB which
> is vendor/OEM-agnostic.
> 
> Isn't that what the compatible property is for?
> -----------------------------------------------
> The compatible property can be used for board matching, but requires
> bootloaders and/or firmware to maintain a database of possible strings
> to match against or have complex compatible string matching. Compatible
> string matching becomes complicated when there are multiple versions of
> board: the device tree selector should recognize a DTB that cares to
> distinguish between v1/v2 and a DTB that doesn't make the distinction.
> An eeprom either needs to store the compatible strings that could match
> against the board or the bootloader needs to have vendor-specific
> decoding logic for the compatible string. Neither increasing eeprom
> storage nor adding vendor-specific decoding logic is desirable.
> 
> The solution proposed here is simpler to implement and doesn't require
> updating firmware or bootloader for every new board.
> 
> How is this better than Qualcomm's qcom,msm-id/qcom,board-id?
> -------------------------------------------------------------
> The selection process for devicetrees was Qualcomm-specific and not
> useful for other devices and bootloaders that were not developed by
> Qualcomm because a complex algorithm was used to implement. Board-ids
> provide a matching solution that can be implemented by bootloaders
> without introducing vendor-specific code. Qualcomm uses three
> devicetree properties: msm-id (interchangeably: soc-id), board-id, and
> pmic-id.  This does not scale well for use casese which use identifiers,
> for example, to distinguish between a display panel. For a display
> panel, an approach could be to add a new property: display-id,
> but now	bootloaders need to be updated to also read this property. We
> want to	avoid requiring to update bootloaders with new hardware
> identifiers: a bootloader need only recognize the identifiers it can
> handle.
> 
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> Signed-off-by: Amrit Anand <quic_amrianan@quicinc.com>
> ---
>  .../devicetree/bindings/hwinfo/board-id.yaml       | 53 ++++++++++++++++++++++
>  1 file changed, 53 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/hwinfo/board-id.yaml
> 
> diff --git a/Documentation/devicetree/bindings/hwinfo/board-id.yaml b/Documentation/devicetree/bindings/hwinfo/board-id.yaml
> new file mode 100644
> index 0000000..82d5ff7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwinfo/board-id.yaml
> @@ -0,0 +1,53 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/hwinfo/board-id.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Board Identifier for Devicetree Selection
> +
> +maintainers:
> +  - Amrit Anand <quic_amrianan@quicinc.com>
> +  - Elliot Berman <quic_eberman@quicinc.com>
> +
> +description: |
> +  Device manufacturers frequently ship multiple boards under a single
> +  software package. These software packages will ship multiple devicetree
> +  blobs and require some mechanism to pick the correct DTB for the board
> +  the software package was deployed. board-id provides a mechanism for
> +  bootloaders to select the appropriate DTB which is vendor/OEM-agnostic.
> +
> +select:
> +  anyOf:
> +    - required:
> +        - 'board-id'
> +    - required:
> +        - 'board-id-types'
> +    - required:
> +        - '#board-id-cells'
> +
> +properties:
> +  $nodename:
> +    const: "/"
> +  board-id:
> +    $ref: /schemas/types.yaml#/definitions/uint32-matrix
> +    description: |
> +      A list of identifiers that can be used to match with this devicetree.
> +      The interpretatation of each cell can be matched with the
> +      board-id-type at the same index.
> +
> +  board-id-types:
> +    $ref: /schemas/types.yaml#/definitions/non-unique-string-array
> +    description:
> +      Defines the type of each cell, indicating to the DeviceTree selection
> +      mechanism how to parse the board-id.
> +
> +  '#board-id-cells':
> +    minimum: 1

This is not how #foo-cells works. It is for provider/consumer style 
bindings.

Rob

Re: [PATCH 1/2] dt-bindings: hwinfo: Introduce board-id

[Krzysztof Kozlowski]

On 24/01/2024 13:42, Amrit Anand wrote:

>>> +select:
>>> +  anyOf:
>>> +    - required:
>>> +        - 'board-id'
>>> +    - required:
>>> +        - 'board-id-types'
>>> +    - required:
>>> +        - '#board-id-cells'
>> I don't fully get why do you need this select. Isn't the schema selected
>> by nodename? Or maybe it is for the final required: but then this could
>> be just set of dependencies.
> The nodename here would be "/". So it will be applied to all the DTs, right?
> Here, we wanted this to apply only if the above mentioned properties are 
> present.

The nodename will select it.

> Do you suggest moving this to qcom,board-id.yaml and the required: as well.
> So that vendor specific yaml could be applied?

I suggest dropping the select.

Different topic is that we cannot even test it because you did not
provide any user of this binding.

>>> +
>>> +properties:
>>> +  $nodename:
>>> +    const: "/"
>> Blank line.
> Will add it.
>>> +  board-id:
>>> +    $ref: /schemas/types.yaml#/definitions/uint32-matrix
>>> +    description: |
>> Do not need '|' unless you need to preserve formatting.
> Ack
>>> +      A list of identifiers that can be used to match with this devicetree.
>> s/devicetree/Devicetree/ ?
> Will update
>>> +      The interpretatation of each cell can be matched with the
>> Typo: interpretation
> Will update
>>> +      board-id-type at the same index.
>>> +
>>> +  board-id-types:
>>> +    $ref: /schemas/types.yaml#/definitions/non-unique-string-array
>>> +    description:
>>> +      Defines the type of each cell, indicating to the DeviceTree selection
>> s/DeviceTree/Devicetree/ ?
> Will update
>>
>>> +      mechanism how to parse the board-id.
>>> +
>>> +  '#board-id-cells':
>>   What are the cells for?
> Bootloader will use this to check the number of entries in a tuple of 
> board-id.

Doesn't the board-id-type define number of cells? How could you have the
same board-id-type with different number of elements on board A and board B?


Best regards,
Krzysztof

Re: [PATCH 0/2] Add board-id support for multiple DT selection

[Amrit Anand]

Sorry for the spam, earlier mail had some formatting issue.

On 1/24/2024 8:26 PM, Rob Herring wrote:
> On Sat, Jan 20, 2024 at 04:50:47PM +0530, Amrit Anand wrote:
>> Device manufacturers frequently ship multiple boards or SKUs under a
>> single software package. These software packages will ship multiple
>> devicetree blobs and require some mechanism to pick the correct DTB for
>> the board the software package was deployed. Introduce a common
>> definition for adding board identifiers to device trees. board-id
>> provides a mechanism for bootloaders to select the appropriate DTB which
>> is vendor/OEM-agnostic.
> Show me a 2nd user. Or does vendor/OEM-agnostic just mean vendors of
> QCom devices? Multiple SoC families using this would help your case. I'm
> not inclined to take it into the DTSpec without that.

Agree; since the DT selection identifiers and algorithm used by various 
DT users has been largely undocumented, we were trying to reach a 
generic solution based on our known use-cases.

>> Isn't that what the compatible property is for?
>> -----------------------------------------------
>> The compatible property can be used for board matching, but requires
>> bootloaders and/or firmware to maintain a database of possible strings
>> to match against or have complex compatible string matching. Compatible
>> string matching becomes complicated when there are multiple versions of
>> board: the device tree selector should recognize a DTB that cares to
>> distinguish between v1/v2 and a DTB that doesn't make the distinction.
>> An eeprom either needs to store the compatible strings that could match
>> against the board or the bootloader needs to have vendor-specific
>> decoding logic for the compatible string. Neither increasing eeprom
>> storage nor adding vendor-specific decoding logic is desirable.
> You could hash the compatible strings if it was just a size issue.
>
>> The solution proposed here is simpler to implement and doesn't require
>> updating firmware or bootloader for every new board.
>>
>> How is this better than Qualcomm's qcom,msm-id/qcom,board-id?
>> -------------------------------------------------------------
>> The selection process for devicetrees was Qualcomm-specific and not
>> useful for other devices and bootloaders that were not developed by
>> Qualcomm because a complex algorithm was used to implement. Board-ids
>> provide a matching solution that can be implemented by bootloaders
>> without introducing vendor-specific code. Qualcomm uses three
>> devicetree properties: msm-id (interchangeably: soc-id), board-id, and
>> pmic-id.  This does not scale well for use casese which use identifiers,
>> for example, to distinguish between a display panel. For a display
>> panel, an approach could be to add a new property: display-id, but now
>> bootloaders need to be updated to also read this property. We want to
>> avoid requiring to update bootloaders with new hardware identifiers: a
>> bootloader need only recognize the identifiers it can handle.
> So the id list will be always expanding list for every last component
> that is 2nd sourced? The ChromeOS folks are also trying to solve that
> problem.

Agree, this could be an expanding list as and when any new hardware 
identifiers for DT selection become pertinent in future.

>
> There's a similar issue for EFI boot with how to select an OS installed
> DTB[1]. You might not care now, but users may later on (like we have
> already with QCom devices with fixed bootloaders). If you do this
> board-id route, then no doubt that compatible values won't be specific
> enough or have suitable fallbacks to be used. Then EFI boot can't use
> compatible either and needs to use this QCom specific logic. It may be a
> common property name, but all the types you defined are QCom specific
> and the matching logic is pretty much undocumented. I'm not saying we
> have to use compatible. There wasn't even agreement to use it for EFI
> boot case. This does need to work for multiple vendors and multiple boot
> scenarios.
>
Agree, given so many hardware identifiers Qcom uses to find the DT based 
on a best and exact match algorithm, it may not work as is for other 
vendors/users outside the scope of Qcom.
Since we have none to very limited visibility into complete set of DT 
selection identifiers being used by other users or into their selection 
algorithms since it is mostly undocumented,
designing a perfectly generic solution (one-size-fits-all) could be 
far-fetched. The number of board files in Qcom DT selection software 
package often reaches over 100 DT files due to multiple SoCs and
board types being supported out of a single software package and these 
multiple hardware identifiers helps to pick the closest best match DT 
within a very large pool of DTs.
Not to affect other users/vendors who would be using their own set of 
identifiers and an entirely different algorithm for DT selection, would 
it make more sense to define these Qcom specific
identifiers within Qcom specific bindings (qcom.yaml), along with 
detailed documentation on our DT selection algorithm?

Thanks,
Amrit

>
> Rob
>
> [1] https://lore.kernel.org/u-boot/20231114232012.GD6601@bill-the-cat/#r

Re: [PATCH 0/2] Add board-id support for multiple DT selection

[Amrit Anand]

On 2/2/2024 10:30 AM, Amrit Anand wrote:
<snip>
>> There's a similar issue for EFI boot with how to select an OS installed
>> DTB[1]. You might not care now, but users may later on (like we have
>> already with QCom devices with fixed bootloaders). If you do this
>> board-id route, then no doubt that compatible values won't be specific
>> enough or have suitable fallbacks to be used. Then EFI boot can't use
>> compatible either and needs to use this QCom specific logic. It may be a
>> common property name, but all the types you defined are QCom specific
>> and the matching logic is pretty much undocumented. I'm not saying we
>> have to use compatible. There wasn't even agreement to use it for EFI
>> boot case. This does need to work for multiple vendors and multiple boot
>> scenarios.
>>
> Agree, given so many hardware identifiers Qcom uses to find the DT 
> based on a best and exact match algorithm, it may not work as is for 
> other vendors/users outside the scope of Qcom.
> Since we have none to very limited visibility into complete set of DT 
> selection identifiers being used by other users or into their 
> selection algorithms since it is mostly undocumented,
> designing a perfectly generic solution (one-size-fits-all) could be 
> far-fetched. The number of board files in Qcom DT selection software 
> package often reaches over 100 DT files due to multiple SoCs and
> board types being supported out of a single software package and these 
> multiple hardware identifiers helps to pick the closest best match DT 
> within a very large pool of DTs.
> Not to affect other users/vendors who would be using their own set of 
> identifiers and an entirely different algorithm for DT selection, 
> would it make more sense to define these Qcom specific
> identifiers within Qcom specific bindings (qcom.yaml), along with 
> detailed documentation on our DT selection algorithm?


I have written a patch for defining Qcom specific identifiers within 
Qcom specific bindings (qcom.yaml) along with documentation on DT 
selection algorithm, would it be okay to send for review?

>
> Thanks,
> Amrit
>
>>
>> Rob
>>
>> [1] https://lore.kernel.org/u-boot/20231114232012.GD6601@bill-the-cat/#r

Re: [PATCH 0/2] Add board-id support for multiple DT selection

[Krzysztof Kozlowski]

On 14/02/2024 13:56, Amrit Anand wrote:
> On 2/2/2024 10:30 AM, Amrit Anand wrote:
> <snip>
>>> There's a similar issue for EFI boot with how to select an OS installed
>>> DTB[1]. You might not care now, but users may later on (like we have
>>> already with QCom devices with fixed bootloaders). If you do this
>>> board-id route, then no doubt that compatible values won't be specific
>>> enough or have suitable fallbacks to be used. Then EFI boot can't use
>>> compatible either and needs to use this QCom specific logic. It may be a
>>> common property name, but all the types you defined are QCom specific
>>> and the matching logic is pretty much undocumented. I'm not saying we
>>> have to use compatible. There wasn't even agreement to use it for EFI
>>> boot case. This does need to work for multiple vendors and multiple boot
>>> scenarios.
>>>
>> Agree, given so many hardware identifiers Qcom uses to find the DT 
>> based on a best and exact match algorithm, it may not work as is for 
>> other vendors/users outside the scope of Qcom.
>> Since we have none to very limited visibility into complete set of DT 
>> selection identifiers being used by other users or into their 
>> selection algorithms since it is mostly undocumented,
>> designing a perfectly generic solution (one-size-fits-all) could be 
>> far-fetched. The number of board files in Qcom DT selection software 
>> package often reaches over 100 DT files due to multiple SoCs and
>> board types being supported out of a single software package and these 
>> multiple hardware identifiers helps to pick the closest best match DT 
>> within a very large pool of DTs.
>> Not to affect other users/vendors who would be using their own set of 
>> identifiers and an entirely different algorithm for DT selection, 
>> would it make more sense to define these Qcom specific
>> identifiers within Qcom specific bindings (qcom.yaml), along with 
>> detailed documentation on our DT selection algorithm?
> 
> 
> I have written a patch for defining Qcom specific identifiers within 
> Qcom specific bindings (qcom.yaml) along with documentation on DT 
> selection algorithm, would it be okay to send for review?

New ideas and patches in good-faith are always welcomed for review, so
go ahead.

What's still missing here is involvement of other SoC vendors: at least
their maintainers and mailing lists.

Best regards,
Krzysztof