linux-kernel - Re: [PATCH v17 07/12] firmware: psci: Implement vendor-specific resets as reboot-mode

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Message-ID: <682b1a0c-644f-2aff-1860-cbf9a53bc62b@oss.qualcomm.com>
Date: Wed, 19 Nov 2025 17:32:42 +0530
From: Shivendra Pratap <shivendra.pratap@....qualcomm.com>
To: Lorenzo Pieralisi <lpieralisi@...nel.org>
Cc: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Sebastian Reichel <sre@...nel.org>, Rob Herring <robh@...nel.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Souvik Chakravarty <Souvik.Chakravarty@....com>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
 <conor+dt@...nel.org>,
        Andy Yan <andy.yan@...k-chips.com>,
        Mark Rutland <mark.rutland@....com>, Arnd Bergmann <arnd@...db.de>,
        Konrad Dybcio <konradybcio@...nel.org>,
        cros-qcom-dts-watchers@...omium.org, Vinod Koul <vkoul@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Florian Fainelli <florian.fainelli@...adcom.com>,
        Moritz Fischer <moritz.fischer@...us.com>,
        John Stultz <john.stultz@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
        Mukesh Ojha <mukesh.ojha@....qualcomm.com>,
        Stephen Boyd <swboyd@...omium.org>,
        Andre Draszik
 <andre.draszik@...aro.org>,
        Kathiravan Thirumoorthy <kathiravan.thirumoorthy@....qualcomm.com>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org,
        Elliot Berman <quic_eberman@...cinc.com>,
        Xin Liu <xin.liu@....qualcomm.com>,
        Srinivas Kandagatla <srini@...nel.org>,
        Umang Chheda <umang.chheda@....qualcomm.com>,
        Nirmesh Kumar Singh <nirmesh.singh@....qualcomm.com>
Subject: Re: [PATCH v17 07/12] firmware: psci: Implement vendor-specific
 resets as reboot-mode



On 11/19/2025 3:07 PM, Lorenzo Pieralisi wrote:
> On Tue, Nov 18, 2025 at 11:11:33PM +0530, Shivendra Pratap wrote:
> 
> [...]
> 
>>> Yes this could be a potential way forward but that's decoupled from the
>>> options below. If we take this route PSCI maintainers should be added
>>> as maintainers for this reboot mode driver.
>>
>> you mean the new psci_reset driver? yes. Maintainer would be PSCI maintainer,
>> if we create a new  psci_reset reboot mode driver.
> 
> Yes.
> 
>>>> - struct with pre-built psci reset_types - (warm, soft, cold). Currently
>>>>   only two modes supported, anything other than warm/soft defaults to cold.
>>>> - vendor resets to be added as per vendor choice, inside psci device tree(SOC specific).
>>>> - psci_reset registers with reboot-mode for registering  vendor resets. Here, we
>>>>   have a problem, the pre-built psci reset_types - (warm, soft, cold) cannot be added via
>>>>   reboot-mode framework.
>>>
>>> Why ?
>>
>> If we want the new psci_reset to take the reboot-mode framework route, is it ok to
>> add default modes (warm, cold) in the device tree?
>> If not, then the design of reboot-mode framework(power:reset:reboot-mode.c) needs to be
>> further changed to equip this new feature. 
> 
> Well, yes, all it needs to do is allowing prepopulated reboot modes on top
> of which DT based ones are added.

The mode-cold , adds a third variable to reboot-modes as the first parameter for 
invoke_psci_fn is different for cold vs warm/vendor.

cold reset call       : invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
vendor/warm reset call: invoke_psci_fn(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2), vendor, cookiee, 0);

Each mode will have 3 argument - like:
_ _ _ _ _ _ _ _ _ _ _ _ _  _ _ _ _ _ _ 
MODE   , cold reset, reset_type, cookie
_ _ _ _ _ _ _ _ _ _ _ _ _  _ _ _ _ _ _ - 
COLD   ,   1       ,    0      ,     0
WARM   ,   0       ,    0      ,     0
vendor1,   0       ,0x80000000 ,     1
vendor2,   0       ,0x80000010 ,     0

So reboot-mode framework will now define and support upto three 32 bit arguments for each mode?

thanks,
Shivendra