linux-kernel - Re: [PATCH v5 1/2] firmware: qcom: scm: Register gunyah watchdog device

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Message-ID: <55kuc3flqzebmfnrerhkz76jqg23xhmc7wiic5faicwtffozgi@xviskbliwgkq>
Date: Wed, 12 Nov 2025 10:26:13 -0600
From: Bjorn Andersson <andersson@...nel.org>
To: Hrishabh Rajput <hrishabh.rajput@....qualcomm.com>
Cc: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>, 
	Pavan Kondeti <pavan.kondeti@....qualcomm.com>, 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, 
	Neil Armstrong <neil.armstrong@...aro.org>, Krzysztof Kozlowski <krzk@...nel.org>
Subject: Re: [PATCH v5 1/2] firmware: qcom: scm: Register gunyah watchdog
 device

On Wed, Nov 12, 2025 at 10:07:26AM +0530, Hrishabh Rajput wrote:
> 
> On 11/11/2025 8:35 PM, Dmitry Baryshkov wrote:
> > On Tue, Nov 11, 2025 at 07:30:59PM +0530, Hrishabh Rajput wrote:
> > > On 11/11/2025 5:52 PM, Dmitry Baryshkov wrote:
> > > > On Tue, Nov 11, 2025 at 11:41:51AM +0100, Krzysztof Kozlowski wrote:
> > > > > On 11/11/2025 11:34, Dmitry Baryshkov wrote:
> > > > > > On Tue, Nov 11, 2025 at 10:51:43AM +0530, Pavan Kondeti wrote:
> > > > > > > On Mon, Nov 10, 2025 at 09:43:53AM +0530, Pavan Kondeti wrote:
> > > > > > > > On Sat, Nov 08, 2025 at 07:26:46PM +0200, Dmitry Baryshkov wrote:
> > > > > > > > > > +static void qcom_scm_gunyah_wdt_free(void *data)
> > > > > > > > > > +{
> > > > > > > > > > +	struct platform_device *gunyah_wdt_dev = data;
> > > > > > > > > > +
> > > > > > > > > > +	platform_device_unregister(gunyah_wdt_dev);
> > > > > > > > > > +}
> > > > > > > > > > +
> > > > > > > > > > +static void qcom_scm_gunyah_wdt_init(struct qcom_scm *scm)
> > > > > > > > > > +{
> > > > > > > > > > +	struct platform_device *gunyah_wdt_dev;
> > > > > > > > > > +	struct device_node *np;
> > > > > > > > > > +	bool of_wdt_available;
> > > > > > > > > > +	int i;
> > > > > > > > > > +	uuid_t gunyah_uuid = UUID_INIT(0xc1d58fcd, 0xa453, 0x5fdb, 0x92, 0x65,
> > > > > > > > > static const?
> > > > > > > > > 
> > > > > > > > > > +				       0xce, 0x36, 0x67, 0x3d, 0x5f, 0x14);
> > > > > > > > > > +	static const char * const of_wdt_compatible[] = {
> > > > > > > > > > +		"qcom,kpss-wdt",
> > > > > > > > > > +		"arm,sbsa-gwdt",
> > > > > > > > > > +	};
> > > > > > > > > > +
> > > > > > > > > > +	/* Bail out if we are not running under Gunyah */
> > > > > > > > > > +	if (!arm_smccc_hypervisor_has_uuid(&gunyah_uuid))
> > > > > > > > > > +		return;
> > > > > > > > > This rquires 'select HAVE_ARM_SMCCC_DISCOVERY'
> > > > > > > > > 
> > > > > > > > Probably `depends on HAVE_ARM_SMCCC_DISCOVERY` is correct here.
> > > > > > > > 
> > > > > > > Dmitry / Bjorn,
> > > > > > > 
> > > > > > > We are debating on this internally on how to resolve this dependency
> > > > > > > 
> > > > > > > - QCOM_SCM depends on HAVE_ARM_SMCCC_DISCOVERY which means restricting
> > > > > > >     QCOM_SCM compilation than what it is today.
> > > > > > > 
> > > > > > > - Adding #ifdefry around arm_smccc_hypervisor_has_uuid usage in qcom scm driver
> > > > > > > 
> > > > > > > - Adding stub for `arm_smccc_hypervisor_has_uuid()` which is not done
> > > > > > >     for any of the functions defined in drivers/firmware/smccc/smccc.c
> > > > > > > 
> > > > > > > We are trending towards the first option above. Please let us know if
> > > > > > > you think otherwise.
> > > > > > The same as before: 'select HAVE_ARM_SMCCC_DISCOVERY'.
> > > > > HAVE_ARM_SMCCC_DISCOVERY has a dependency which is not always selected
> > > > > (e.g. ARM32), thus selecting it might lead to warnings of unmet
> > > > > dependencies.
> > > > Then `if (!IS_ENABLED(CONFIG_HAVE_ARM_SMCCC_DISCOVERY))` might be a good
> > > > option here (and depend on GICv3 selecting it).
> > > Thanks a lot Dmitry, wemade the change below and compile tested on various
> > > architectures (ARM64, ARM32, x86, PowerPC, RISC-V and MIPS) and it was
> > > success.
> > > 
> > > We will include it in our next patch version, if there are no further
> > > concerns.
> > > 
> > > }; /* Bail out if we are not running under Gunyah */ - if
> > > (!arm_smccc_hypervisor_has_uuid(&gunyah_uuid)) + if
> > > (!IS_ENABLED(CONFIG_HAVE_ARM_SMCCC_DISCOVERY) || +
> > > !arm_smccc_hypervisor_has_uuid(&gunyah_uuid)) return; /*
> > Unreadable. Don't you read what you are sending?
> 
> Sorry, my mail client messed up the formatting while sending. Here is the
> proper version:
> 
> /* Bail out if we are not running under Gunyah */
> -	if (!arm_smccc_hypervisor_has_uuid(&gunyah_uuid))
> +	if (!IS_ENABLED(CONFIG_HAVE_ARM_SMCCC_DISCOVERY) ||
> +	    !arm_smccc_hypervisor_has_uuid(&gunyah_uuid))
> 		return;

LGTM

> 
> Thanks,
> Hrishabh
>