On 22/06/2022 10:00, Krzysztof Kozlowski wrote:
On 21/06/2022 21:49, Dmitry Baryshkov wrote:
On Tue, 21 Jun 2022 at 22:32, Krzysztof Kozlowski
<krzysztof.kozlowski@xxxxxxxxxx> wrote:
On 21/06/2022 21:26, 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.
I might be mistaken here. I think it was expected that dtbTool would use
board compat strings to generate qcom,msm-id and qcom,board-id
properties. It's not that the bootloaders were improved.
Don't ask me, I am new to this.
https://lore.kernel.org/all/02ab0276-b078-fe66-8596-fcec4378722b@xxxxxxxxxxxxxx/
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@xxxxxxxxxx/
Co-developed-by: Kumar Gala <galak@xxxxxxxxxxxxxx>
Signed-off-by: Kumar Gala <galak@xxxxxxxxxxxxxx>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
---
.../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::
two bitfields
Right, thanks.
+ - 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).
Could you please elaborate this?
Second paragraph:
https://lore.kernel.org/all/20220522195138.35943-1-konrad.dybcio@xxxxxxxxxxxxxx/
I think this is something peculiar to Sony. Public lahaina (sm8350)
dts files contain both these properties:
https://github.com/MiCode/kernel_devicetree/blob/zeus-s-oss/qcom/lahaina-hdk.dts
https://github.com/MiCode/kernel_devicetree/blob/zeus-s-oss/qcom/lahaina-v2.1.dtsi
Plus consensus with Rob:
https://lore.kernel.org/all/CAL_JsqKL-mtAQ8Q9H4vLGM8izVVzDPbUAVWSdS8AmGjN6X6kcA@xxxxxxxxxxxxxx/
I'm not sure here. But sm8350 and sm8450 dtsi files use these
properties. I've linked lahaina files above.
The waiptio dtsi (sm8450) are present at the same URL.
If you did not like where the consensus is going during the discussion
last week, I would expect to join the discussion. Not to comment after I
implement it.
Please excuse me. I probably missed that part of the discussion. Yes, it
was my fault.
If the AOSP team were to add e.g.
SM8350-HDK to their single RB3+RB5 images, they would still need the
qcom,board-id/qcom,msm-id properties to let the bootloader choose proper
DTB.
If you have any email addresses in mind, please Cc them to invite in
discussions. Otherwise I am afraid it won't be allowed. The feedback I
got before was that SM8350 and newer do not require this property. Feel
free to propose other way to solve comments (see "consensus with Rob"
above).
Amit is in CC list. In the past he used these properties to allow
single-image booting of RB3 and RB5.
In fact I might prefer adding more of these properties to the dts
files, where it makes sense, to allow adding more dt files to the
images we create.
I'd really like to be able to boot a single image on all my boards
(rb3, rb5, db410c, db820, ifc6560, etc).
You have several options here. Use the board-compatible-encoded-scheme,
which was merged like 6 years ago or something. Bootloader could parse
it, dtbTool as well. Add a generic property, like Rob wanted (and
probably fix bootloader). Or find any other way to satisfy Rob's
comments. These properties were not accepted 6 years ago and the board
compatible approach was merged instead. If 6 years is not enough to
change the bootloaders, nothing will happen here ever, so we need to
make some statement.
Let me respond to his email. Amit, you might have something to add there
too.
Basically I think we should allow these properties to be used for all
the Qcom boards. Marking them as 'deprecated' is fine to me, thus we
would not endorse them. But we would still be able to use them when
needed/wanted (like AOSP requirements for the single boot image).
--
With best wishes
Dmitry
