linux-kernel - Re: [PATCH v8 2/2] watchdog: Add driver for Gunyah Watchdog

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Message-ID: <20251211132038.mt3tuqw535vdo3rh@hu-mojha-hyd.qualcomm.com>
Date: Thu, 11 Dec 2025 18:50:38 +0530
From: Mukesh Ojha <mukesh.ojha@....qualcomm.com>
To: Hrishabh Rajput <hrishabh.rajput@....qualcomm.com>
Cc: Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Guenter Roeck <linux@...ck-us.net>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>, linux-arm-msm@...r.kernel.org,
        linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Pavan Kondeti <pavan.kondeti@....qualcomm.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
        Shivendra Pratap <shivendra.pratap@....qualcomm.com>
Subject: Re: [PATCH v8 2/2] watchdog: Add driver for Gunyah Watchdog

On Tue, Nov 18, 2025 at 10:40:57AM +0000, Hrishabh Rajput wrote:
> On Qualcomm SoCs running under the Gunyah hypervisor, access to watchdog
> through MMIO is not available on all platforms. Depending on the
> hypervisor configuration, the watchdog is either fully emulated or
> exposed via ARM's SMC Calling Conventions (SMCCC) through the Vendor
> Specific Hypervisor Service Calls space.
> 
> Add driver to support the SMC-based watchdog provided by the Gunyah
> Hypervisor. Device registration is done in the QCOM SCM driver after
> checks to restrict the watchdog initialization to Qualcomm devices
> running under Gunyah.
> 
> Gunyah watchdog is not a hardware but an SMC-based vendor-specific
> hypervisor interface provided by the Gunyah hypervisor. The design
> involving QCOM SCM driver for registering the platform device has been
> devised to avoid adding non-hardware nodes to devicetree.
> 
> Tested-by: Shivendra Pratap <shivendra.pratap@....qualcomm.com>
> Tested-by: Neil Armstrong <neil.armstrong@...aro.org>
> Signed-off-by: Hrishabh Rajput <hrishabh.rajput@....qualcomm.com>

I wanted to test the latest mem-inspect (Minidump) patches, but due to a
firmware bug, my last log after crash messages were not being captured. This
forced me to get another device. I had an SM8750, but it does not
support dump collection because of the missing Gunyah watchdog support
in the upstream. Luckily, this series came to the rescue, and now I am
able to capture the last crash messages.

Feel free to add

Tested-by: Mukesh Ojha <mukesh.ojha@....qualcomm.com>

to the series.

-- 
-Mukesh Ojha