Re: [PATCH] arm64: dts: qcom: pad sa8155p-adp DTB file

[Stephan Gerhold <stephan@gerhold.net>]

On Wed, Oct 11, 2023 at 02:19:36PM +0300, Dmitry Baryshkov wrote:
> On sa8155p-adp platfor the bootloader (ABL) fails to reserve enough
> memory for updating the DTB:
> 
> Cmdline:  console=tty0 console=ttyMSM0,115200n8 androidboot.verifiedbootstate
> Error adding node
> Error carving out UEFI memory: FFFFFFFF
> 
> Adding `--pad 1024' to DTC_FLAGS for this board fixes the issue by
> providing enough empty space for node creation.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
> 
> This replaces my previous attempt, which added DTC_FLAGS globally ([1]),
> which was rejected.
> 
> [1] https://lore.kernel.org/linux-arm-msm/20231009172717.2695854-1-dmitry.baryshkov@linaro.org/
> 

Thanks for making this specific to sa8155p-adp. I completely agree that
this workaround might be needed for devices that are locked down (with
no way to update the bootloader).

But is this really the case here? As far as I understand, the SA8155P
ADP is the "Automotive Development Platform", i.e. a developer board
where I would expect that secure boot is not enabled (just like on the
DragonBoards and RoboticBoards).

Fixing this properly in the bootloader would be very easy, you just need
to increase the DTB_PAD_SIZE I linked [1] by 1024 like in this patch.
This would fix the issue properly, with no change needed in Linux. And
if you have some way to communicate/contribute this back to Qualcomm
somehow we could reduce the chance to see this problem on actually
locked down devices in the future.

Thanks,
Stephan

[1]: https://git.codelinaro.org/clo/la/abl/tianocore/edk2/-/blob/LA.AU.1.4.1.r2-05100-sa8155.0/QcomModulePkg/Include/Library/LocateDeviceTree.h#L59