Re: [PATCH 19/21] google/gs101: Add dt overlay for oriole board

[William McVicker <willmcvicker@xxxxxxxxxx>]

On 10/05/2023, Krzysztof Kozlowski wrote:
> On 05/10/2023 17:56, Peter Griffin wrote:
> > The LK bootloader on Pixel6 searches for a dt overlay in the
> > dtbo partition with a board_id and board_rev that matches
> > what is baked into the device. If this overlay is not present
> > then the phone will bootloop in fastboot and you can't boot
> > the upstream kernel.
> > 
> > This commit adds a dtbo for the production oriole variant.
> > The other pre-production board overlays are not included
> > at this time.
> > 
> > Adding the dtbo here allows for a better experience when
> > building/booting the upstream kernel on Pixel devices
> > as all the DT required to boot the device will be created
> > as part of the kernel build process. Rather than having to
> > fetch the dtbo from some other repo.
> > 
> > Signed-off-by: Peter Griffin <peter.griffin@xxxxxxxxxx>
> > ---
> >  arch/arm64/boot/dts/google/Makefile          |  1 +
> >  arch/arm64/boot/dts/google/gs101-oriole.dtso | 21 ++++++++++++++++++++
> >  2 files changed, 22 insertions(+)
> >  create mode 100644 arch/arm64/boot/dts/google/gs101-oriole.dtso
> > 
> > diff --git a/arch/arm64/boot/dts/google/Makefile b/arch/arm64/boot/dts/google/Makefile
> > index 6d2026a767d4..3f1761f8daa9 100644
> > --- a/arch/arm64/boot/dts/google/Makefile
> > +++ b/arch/arm64/boot/dts/google/Makefile
> > @@ -2,5 +2,6 @@
> >  
> >  dtb-$(CONFIG_ARCH_GOOGLE_TENSOR) += \
> >  	gs101-oriole.dtb \
> > +	gs101-oriole.dtbo
> >  
> >  
> > diff --git a/arch/arm64/boot/dts/google/gs101-oriole.dtso b/arch/arm64/boot/dts/google/gs101-oriole.dtso
> > new file mode 100644
> > index 000000000000..50832fd94204
> > --- /dev/null
> > +++ b/arch/arm64/boot/dts/google/gs101-oriole.dtso
> > @@ -0,0 +1,21 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Oriole DVT Device Tree
> > + *
> > + * Copyright 2021-2023 Google,LLC
> > + */
> > +
> > +/dts-v1/;
> > +/plugin/;
> > +
> > +/ {
> > +	board_id = <0x20304>;
> > +	board_rev = <0x10000>;
> 
> Undocumented properties. Please propose bindings... Also, underscores
> are not allowed, so in this form it is a no-go... although I understand
> the pain of not being able to change the bootloader.
> 
> For reference:
> https://lore.kernel.org/all/20220605150747.GA3465286-robh@xxxxxxxxxx/
> https://lore.kernel.org/all/20220610163343.GA1787330-robh@xxxxxxxxxx/

These names are actually arbitrary and don't depend on the bootloader. They are
passed into the mkdtimg tool [1] using --id and --rev and used to create the
dt_table_entries. The bootloader traverses the table and picks the overlay
based on these properties. So we can use whatever property names we want
without changing the bootloader.

[1] https://android.googlesource.com/platform/system/libufdt/+/refs/heads/main/utils/

Thanks,
Will

> 
> 
> Best regards,
> Krzysztof
>