Hi Bjorn, Krzysztof,
On Mon, 26 Sept 2022 at 13:30, Krzysztof Kozlowski
<krzysztof.kozlowski@xxxxxxxxxx> wrote:
>
> On 30/08/2022 08:57, 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 along with the bindings header with constants
> > used by: bootloader, some DTS and socinfo driver.
> >
> > 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>
> > Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
> >
> > ---
> >
> > Changes since v6:
> > 1. Update header with defines
> > 2. Add Rb tag
>
> Hi Bjorn,
>
> Any further comments on this? Can it be applied?
A gracious ping from my side. I think it would be better to apply this
patch rather than having the undocumented and controversial propreties
in the device trees.
--
With best wishes
Dmitry
