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Message-ID: <417cb5cb-01f5-4d01-8bbe-aa2286fca43e@linaro.org>
Date: Mon, 20 Nov 2023 11:55:24 +0100
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Elliot Berman <quic_eberman@...cinc.com>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>,
Lorenzo Pieralisi <lpieralisi@...nel.org>,
Mark Rutland <mark.rutland@....com>
Cc: Satya Durga Srinivasu Prabhala <quic_satyap@...cinc.com>,
Melody Olvera <quic_molvera@...cinc.com>,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
Florian Fainelli <florian.fainelli@...adcom.com>
Subject: Re: [PATCH 0/3] Implement vendor resets for PSCI SYSTEM_RESET2
On 17/11/2023 22:18, 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, but not 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.
>
> 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/
Please link here upstream DTS user for this.
Best regards,
Krzysztof
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