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

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Message-ID: <68dbaf42-0d64-45f7-8410-ebcbae2da612@oss.qualcomm.com>
Date: Wed, 12 Nov 2025 10:07:26 +0530
From: Hrishabh Rajput <hrishabh.rajput@....qualcomm.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Pavan Kondeti <pavan.kondeti@....qualcomm.com>,
        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,
        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 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;

Thanks,
Hrishabh