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@xxxxxxxxxxx>
> > Signed-off-by: Amrit Anand <quic_amrianan@xxxxxxxxxxx>
> > ---
> >   .../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@xxxxxxxxxxx>
> > +  - Elliot Berman <quic_eberman@xxxxxxxxxxx>
> > +
> > +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.