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Message-ID: <3ccbcaa0-d5b6-9f46-03c3-2a3e0ee72782@linaro.org>
Date: Wed, 22 Jun 2022 12:44:22 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
Andy Gross <agross@...nel.org>,
Bjorn Andersson <bjorn.andersson@...aro.org>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Konrad Dybcio <konrad.dybcio@...ainline.org>,
Amit Pundir <amit.pundir@...aro.org>,
Trilok Soni <quic_tsoni@...cinc.com>,
Rob Clark <robdclark@...il.com>,
Stephan Gerhold <stephan@...hold.net>,
Kumar Gala <galak@...eaurora.org>,
Stephen Boyd <sboyd@...nel.org>
Subject: Re: [PATCH v2 1/2] dt-bindings: arm: qcom: document qcom,msm-id and
qcom,board-id
On 21/06/2022 21:56, Krzysztof Kozlowski wrote:
> The top level qcom,msm-id and qcom,board-id properties are utilized by
> bootloaders on Qualcomm MSM platforms to determine which device tree
> should be used and passed to the kernel.
>
> The commit b32e592d3c28 ("devicetree: bindings: Document qcom board
> compatible format") from 2015 was a consensus during discussion about
> upstreaming qcom,msm-id and qcom,board-id fields. There are however still
> problems with that consensus:
> 1. It was reached 7 years ago but it turned out its implementation did
> not reach all possible products.
>
> 2. Initially additional tool (dtbTool) was needed for parsing these
> fields to create a QCDT image consisting of multiple DTBs, later the
> bootloaders were improved and they use these qcom,msm-id and
> qcom,board-id properties directly.
>
> 3. Extracting relevant information from the board compatible requires
> this additional tool (dtbTool), which makes the build process more
> complicated and not easily reproducible (DTBs are modified after the
> kernel build).
>
> 4. Some versions of Qualcomm bootloaders expect these properties even
> when booting with a single DTB. The community is stuck with these
> bootloaders thus they require properties in the DTBs.
>
> Since several upstreamed Qualcomm SoC-based boards require these
> properties to properly boot and the properties are reportedly used by
> bootloaders, document them.
>
> Link: https://lore.kernel.org/r/a3c932d1-a102-ce18-deea-18cbbd05ecab@linaro.org/
> Co-developed-by: Kumar Gala <galak@...eaurora.org>
> Signed-off-by: Kumar Gala <galak@...eaurora.org>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> ---
> .../devicetree/bindings/arm/qcom.yaml | 123 ++++++++++++++++++
> include/dt-bindings/arm/qcom,ids.h | 30 +++++
> 2 files changed, 153 insertions(+)
> create mode 100644 include/dt-bindings/arm/qcom,ids.h
>
> diff --git a/Documentation/devicetree/bindings/arm/qcom.yaml b/Documentation/devicetree/bindings/arm/qcom.yaml
> index 6c38c1387afd..05b98cde4653 100644
> --- a/Documentation/devicetree/bindings/arm/qcom.yaml
> +++ b/Documentation/devicetree/bindings/arm/qcom.yaml
> @@ -403,6 +403,129 @@ properties:
> - qcom,sm8450-qrd
> - const: qcom,sm8450
>
> + # Board compatibles go above
> +
> + qcom,msm-id:
> + $ref: /schemas/types.yaml#/definitions/uint32-matrix
> + minItems: 1
> + maxItems: 8
> + items:
> + items:
> + - description: |
> + MSM chipset ID - an exact match value consisting of three bitfields::
> + - bits 0-15 - The unique MSM chipset ID
> + - bits 16-31 - Reserved; should be 0
> + - description: |
> + Hardware revision ID - a chipset specific 32-bit ID representing
> + the version of the chipset. It is best a match value - the
> + bootloader will look for the closest possible match.
> + deprecated: true
> + description:
> + The MSM chipset and hardware revision use by Qualcomm bootloaders. It
> + can optionally be an array of these to indicate multiple hardware that
> + use the same device tree. It is expected that the bootloader will use
> + this information at boot-up to decide which device tree to use when given
> + multiple device trees, some of which may not be compatible with the
> + actual hardware. It is the bootloader's responsibility to pass the
> + correct device tree to the kernel.
> + The property is deprecated - it is not expected on newer boards
> + (starting with SM8350).
I have been thinking about this for quite a while. I think this patch is
good.
With this paragraph (and the corresponding paragraph from the next item)
rephrased to remove references to 'newer boards':
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> +
> + qcom,board-id:
> + $ref: /schemas/types.yaml#/definitions/uint32-matrix
> + minItems: 1
> + maxItems: 8
> + items:
> + oneOf:
> + - maxItems: 2
> + items:
> + - description: |
> + Board ID consisting of three bitfields::
> + - bits 31-24 - Unused
> + - bits 23-16 - Platform Version Major
> + - bits 15-8 - Platform Version Minor
> + - bits 7-0 - Platform Type
> + Platform Type field is an exact match value. The
> + Platform Major/Minor field is a best match. The bootloader will
> + look for the closest possible match.
> + - description: |
> + Subtype ID unique to a Platform Type/Chipset ID. For a given
> + Platform Type, there will typically only be a single board and the
> + subtype_id will be 0. However in some cases board variants may
> + need to be distinguished by different subtype_id values.
> + # OnePlus uses a variant of board-id with four elements:
> + - minItems: 4
> + items:
> + - const: 8
> + - const: 0
> + - description: OnePlus board ID
> + - description: OnePlus subtype ID
> + deprecated: true
> + description:
> + The board type and revision information. It can optionally be an array
> + of these to indicate multiple boards that use the same device tree. It
> + is expected that the bootloader will use this information at boot-up to
> + decide which device tree to use when given multiple device trees, some of
> + which may not be compatible with the actual hardware. It is the
> + bootloader's responsibility to pass the correct device tree to the
> + kernel
> + The property is deprecated - it is not expected on newer boards
> + (starting with SM8350).
> +
> +allOf:
> + # Explicit allow-list for older SoCs. The legacy properties are not allowed
> + # on newer SoCs.
> + - if:
> + properties:
> + compatible:
> + contains:
> + enum:
> + - qcom,apq8026
> + - qcom,apq8094
> + - qcom,apq8096
> + - qcom,msm8992
> + - qcom,msm8994
> + - qcom,msm8996
> + - qcom,msm8998
> + - qcom,sdm630
> + - qcom,sdm632
> + - qcom,sdm845
> + - qcom,sdx55
> + - qcom,sdx65
> + - qcom,sm6125
> + - qcom,sm6350
> + - qcom,sm7225
> + - qcom,sm8150
> + - qcom,sm8250
> + then:
> + properties:
> + qcom,board-id: true
> + qcom,msm-id: true
> + else:
> + properties:
> + qcom,board-id: false
> + qcom,msm-id: false
> +
> + - if:
> + properties:
> + compatible:
> + contains:
> + enum:
> + - oneplus,cheeseburger
> + - oneplus,dumpling
> + - oneplus,enchilada
> + - oneplus,fajita
> + then:
> + properties:
> + qcom,board-id:
> + items:
> + minItems: 4
> + else:
> + properties:
> + qcom,board-id:
> + items:
> + maxItems: 2
> +
> additionalProperties: true
>
> ...
> diff --git a/include/dt-bindings/arm/qcom,ids.h b/include/dt-bindings/arm/qcom,ids.h
> new file mode 100644
> index 000000000000..eaf86c18650f
> --- /dev/null
> +++ b/include/dt-bindings/arm/qcom,ids.h
> @@ -0,0 +1,30 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (c) 2015, The Linux Foundation. All rights reserved.
> + * Copyright (c) 2022 Linaro Ltd
> + * Author: Krzysztof Kozlowski <krzk@...nel.org> based on previous work of Kumar Gala.
> + */
> +#ifndef _DT_BINDINGS_ARM_QCOM_IDS_H
> +#define _DT_BINDINGS_ARM_QCOM_IDS_H
> +
> +/* qcom,msm-id */
> +#define QCOM_ID_APQ8026 199
> +#define QCOM_ID_MSM8916 206
> +#define QCOM_ID_MSM8994 207
> +#define QCOM_ID_MSM8996_3_0 246
> +#define QCOM_ID_APQ8016 247
> +#define QCOM_ID_MSM8216 248
> +#define QCOM_ID_MSM8116 249
> +#define QCOM_ID_MSM8616 250
> +#define QCOM_ID_MSM8998 292
> +#define QCOM_ID_SDM845 321
> +
> +/* qcom,board-id */
> +#define QCOM_BOARD_ID(a, major, minor) \
> + (((major & 0xff) << 16) | ((minor & 0xff) << 8) | QCOM_BOARD_ID_##a)
> +
> +#define QCOM_BOARD_ID_MTP 8
> +#define QCOM_BOARD_ID_DRAGONBOARD 10
> +#define QCOM_BOARD_ID_SBC 24
> +
> +#endif /* _DT_BINDINGS_ARM_QCOM_IDS_H */
--
With best wishes
Dmitry
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