Re: [PATCH v8 0/6] Implement vendor resets for PSCI SYSTEM_RESET2

[Elliot Berman <quic_eberman@quicinc.com>]

Hi Lorenzo,

I haven't seen response on our question about how reboot_mode enum and
reboot command string are supposed to interact. Let's make a call
ourselves and merge?

Thanks,
Elliot

On Thu, Nov 07, 2024 at 03:38:24PM -0800, Elliot Berman wrote:
> The PSCI SYSTEM_RESET2 call allows vendor firmware to define additional
> reset types which could be mapped to the reboot argument.
> 
> Setting up reboot on Qualcomm devices can be inconsistent from chipset
> to chipset. Generally, there is a PMIC register that gets written to
> decide the reboot type. There is also sometimes a cookie that can be
> written to indicate that the bootloader should behave differently than a
> regular boot. These knobs evolve over product generations and require 
> more drivers. Qualcomm firmwares are beginning to expose vendor
> SYSTEM_RESET2 types to simplify driver requirements from Linux.
> 
> Add support in PSCI to statically wire reboot mode commands from
> userspace to a vendor reset and cookie value using the device tree. The
> DT bindings are similar to reboot mode framework except that 2
> integers are accepted (the type and cookie). Also, reboot mode framework
> is intended to program the cookies, but not actually reboot the host.
> PSCI SYSTEM_RESET2 does both. I've not added support for reading ACPI
> tables since I don't have any device which provides them + firmware that
> supports vendor SYSTEM_RESET2 types.
> 
> Lorenzo and I are also looking for some feedback on whether it is safe
> to perform a vendor SYSTEM_RESET2 irrespective of the enum reboot_mode:
> 
> https://lore.kernel.org/all/Zw5ffeYW5uRpsaG3@lpieralisi/
> 
> Previous discussions around SYSTEM_RESET2:
> - https://lore.kernel.org/lkml/20230724223057.1208122-2-quic_eberman@quicinc.com/T/
> - https://lore.kernel.org/all/4a679542-b48d-7e11-f33a-63535a5c68cb@quicinc.com/
> 
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> 
> Changes in v8:
> - Code style nits from Stephen
> - Add rb3gen2
> - Link to v7: https://lore.kernel.org/r/20241028-arm-psci-system_reset2-vendor-reboots-v7-0-a4c40b0ebc54@quicinc.com
> 
> Changes in v7:
> - Code style nits from Stephen
> - Dropped unnecessary hunk from the sa8775p-ride patch
> - Link to v6: https://lore.kernel.org/r/20241018-arm-psci-system_reset2-vendor-reboots-v6-0-50cbe88b0a24@quicinc.com
> 
> Changes in v6:
> - Rebase to v6.11 and fix trivial conflicts in qcm6490-idp
> - Add sa8775p-ride support (same as qcm6490-idp)
> - Link to v5: https://lore.kernel.org/r/20240617-arm-psci-system_reset2-vendor-reboots-v5-0-086950f650c8@quicinc.com
> 
> Changes in v5:
> - Drop the nested "items" in prep for future dtschema tools
> - Link to v4: https://lore.kernel.org/r/20240611-arm-psci-system_reset2-vendor-reboots-v4-0-98f55aa74ae8@quicinc.com
> 
> Changes in v4:
> - Change mode- properties from uint32-matrix to uint32-array
> - Restructure the reset-types node so only the restriction is in the
>   if/then schemas and not the entire definition
> - Link to v3: https://lore.kernel.org/r/20240515-arm-psci-system_reset2-vendor-reboots-v3-0-16dd4f9c0ab4@quicinc.com
> 
> Changes in v3:
> - Limit outer number of items to 1 for mode-* properties
> - Move the reboot-mode for psci under a subnode "reset-types"
> - Fix the DT node in qcm6490-idp so it doesn't overwrite the one from
>   sc7820.dtsi
> - Link to v2: https://lore.kernel.org/r/20240414-arm-psci-system_reset2-vendor-reboots-v2-0-da9a055a648f@quicinc.com
> 
> Changes in v2:
> - Fixes to schema as suggested by Rob and Krzysztof
> - Add qcm6490 idp as first Qualcomm device to support
> - Link to v1: https://lore.kernel.org/r/20231117-arm-psci-system_reset2-vendor-reboots-v1-0-03c4612153e2@quicinc.com
> 
> Changes in v1:
> - Reference reboot-mode bindings as suggeted by Rob.
> - Link to RFC: https://lore.kernel.org/r/20231030-arm-psci-system_reset2-vendor-reboots-v1-0-dcdd63352ad1@quicinc.com
> 
> ---
> Elliot Berman (6):
>       dt-bindings: power: reset: Convert mode-.* properties to array
>       dt-bindings: arm: Document reboot mode magic
>       firmware: psci: Read and use vendor reset types
>       arm64: dts: qcom: qcm6490-idp: Add PSCI SYSTEM_RESET2 types
>       arm64: dts: qcom: qcs6490-rb3gen2: Add PSCI SYSTEM_RESET2 types
>       arm64: dts: qcom: sa8775p-ride: Add PSCI SYSTEM_RESET2 types
> 
>  Documentation/devicetree/bindings/arm/psci.yaml    |  43 +++++++++
>  .../bindings/power/reset/nvmem-reboot-mode.yaml    |   4 +
>  .../devicetree/bindings/power/reset/qcom,pon.yaml  |   7 ++
>  .../bindings/power/reset/reboot-mode.yaml          |   4 +-
>  .../bindings/power/reset/syscon-reboot-mode.yaml   |   4 +
>  arch/arm64/boot/dts/qcom/qcm6490-idp.dts           |   7 ++
>  arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts       |   7 ++
>  arch/arm64/boot/dts/qcom/sa8775p-ride.dtsi         |   7 ++
>  arch/arm64/boot/dts/qcom/sa8775p.dtsi              |   2 +-
>  arch/arm64/boot/dts/qcom/sc7280.dtsi               |   2 +-
>  drivers/firmware/psci/psci.c                       | 104 +++++++++++++++++++++
>  11 files changed, 187 insertions(+), 4 deletions(-)
> ---
> base-commit: 98f7e32f20d28ec452afb208f9cffc08448a2652
> change-id: 20231016-arm-psci-system_reset2-vendor-reboots-cc3ad456c070
> 
> Best regards,
> -- 
> Elliot Berman <quic_eberman@quicinc.com>
>