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@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.
> 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