Messages in this thread | | | Date | Wed, 22 Jun 2022 12:50:48 +0300 | Subject | Re: [PATCH v2 1/2] dt-bindings: arm: qcom: document qcom,msm-id and qcom,board-id | From | Dmitry Baryshkov <> |
| |
On 22/06/2022 12:49, Krzysztof Kozlowski wrote: > On 22/06/2022 11:44, Dmitry Baryshkov wrote: >> 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@codeaurora.org> >>> Signed-off-by: Kumar Gala <galak@codeaurora.org> >>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.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@linaro.org> > > Great, thanks! And thank you for responding in previous discussions. > > I'll remove entire "newer boards ..." part, fix the "two bitfields" and > change the name of the define QCOM_ID_MSM8996. I won't add more board > IDs yet, this can be in following up patches (not only my me).
This sounds perfect to me. Thanks a lot for your work on sorting this out!
-- With best wishes Dmitry
| |