Re: [PATCH v2 0/2] Add psci_sys_reset2 reboot modes for Qualcomm boards

[Bjorn Andersson <andersson@kernel.org>]

On Mon, Jun 15, 2026 at 06:38:59PM +0530, Shivendra Pratap wrote:
> 
> 
> On 12-06-2026 13:51, Lorenzo Pieralisi wrote:
> > On Wed, Jun 10, 2026 at 02:57:19PM +0200, Loic Poulain wrote:
> > > Hi Anurag,
> > > 
> > > On Fri, May 29, 2026 at 4:29 PM Anurag Pateriya
> > > <anurag.pateriya@oss.qualcomm.com> wrote:
> > > > 
> > > > Adding PSCI SYSTEM_RESET2 reboot-modes for sm8750 and
> > > > kaanapali based boards.
> > > 
> > > I would like to highlight that when Linux/EFI is enabled, which is a
> > > common config, efi_reboot is used as the primary reboot path (see
> > > machine_restart).
> 
> Yes but, only if EFI RESET RUNTIME service is enabled by UEFI.
> 
> efi_reboot(...) {
> ..
>          if (!efi_rt_services_supported(EFI_RT_SUPPORTED_RESET_SYSTEM))
>                   return;
> ..
> 
> > > As a result, the PSCI reboot hook is not invoked in
> > > this scenario, assuming Qualcomm firmware provides EFI runtime
> > > services.
> 
> Currently EFI RUNTIME RESET service is not enabled on these firmware.
> 

We have every intent to align with these standards, so this will become
a valid concern.

> > > As a follow-up, it would therefore be beneficial to also
> > > improve the EFI path to support such custom mode(s)...
> 
> Yes, and potentially linux should also have some control, if it wants to
> go via efi reset path or the PSCI reset path.
> 

Please stop thinking in terms of embedded system. Things like this
should just work, it should not rely on userspace to tinker with every
available knob.


That said, I think Loic's concern should be considered feedback on the
implementation - and specifically the DT binding in that series. Given
those bindings, I think these patches looks good - but the version of
the dependency that is being linked to has change requests, so please
resubmit this once it's possible to merge.

Regards,
Bjorn

> thanks,
> Shivendra
> 
> > 
> > I have not checked but we should probably put in a place a way for user
> > space to check that PSCI is _not_ the reboot method that will be
> > used, lest it would be allowed to send commands to the kernel that
> > would be duly ignored.
> > 
> > Need to go through the whole thing again before commenting any further.
> > 
> > Thanks,
> > Lorenzo
> > 
> > > Regards,
> > > Loic
> > > 
> > > 
> > > 
> > > > 
> > > > These DT patches depend on PSCI SYSTEM_RESET2 support introduced in:
> > > > https://lore.kernel.org/all/20260514-arm-psci-system_reset2-vendor-reboots-v22-0-28a5bde07483@oss.qualcomm.com/
> > > > 
> > > > To: Bjorn Andersson <andersson@kernel.org>
> > > > To: Konrad Dybcio <konradybcio@kernel.org>
> > > > To: Rob Herring <robh@kernel.org>
> > > > To: Krzysztof Kozlowski <krzk+dt@kernel.org>
> > > > To: Conor Dooley <conor+dt@kernel.org>
> > > > Cc: Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>
> > > > Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>
> > > > Cc: linux-arm-msm@vger.kernel.org
> > > > Cc: devicetree@vger.kernel.org
> > > > Cc: linux-kernel@vger.kernel.org
> > > > 
> > > > Signed-off-by: Anurag Pateriya <anurag.pateriya@oss.qualcomm.com>
> > > > ---
> > > > Changes in v2:
> > > > - Fixed subject lines.
> > > > - Link to v1: https://lore.kernel.org/r/20260529-psci_sys_reset-dt-changes-for-pakala-v1-0-7c32161cf50b@oss.qualcomm.com
> > > > 
> > > > ---
> > > > Anurag Pateriya (1):
> > > >        arm64: dts: qcom: sm8750: add reboot-mode support
> > > > 
> > > > Xin Liu (1):
> > > >        arm64: dts: qcom: kaanapali: add reboot-mode support
> > > > 
> > > >   arch/arm64/boot/dts/qcom/kaanapali-mtp.dts | 7 +++++++
> > > >   arch/arm64/boot/dts/qcom/kaanapali-qrd.dts | 7 +++++++
> > > >   arch/arm64/boot/dts/qcom/kaanapali.dtsi    | 2 +-
> > > >   arch/arm64/boot/dts/qcom/sm8750-mtp.dts    | 7 +++++++
> > > >   arch/arm64/boot/dts/qcom/sm8750-qrd.dts    | 7 +++++++
> > > >   arch/arm64/boot/dts/qcom/sm8750.dtsi       | 2 +-
> > > >   6 files changed, 30 insertions(+), 2 deletions(-)
> > > > ---
> > > > base-commit: 6ee02bbf328be8a8586487e3af73b65a906cce58
> > > > change-id: 20260529-psci_sys_reset-dt-changes-for-pakala-a09fc0e2a8a8
> > > > 
> > > > Best regards,
> > > > --
> > > > Anurag Pateriya <anurag.pateriya@oss.qualcomm.com>
> > > > 
> > > > 
>