linux-kernel - Re: [PATCH v3] watchdog: Add driver for Gunyah Watchdog

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Message-ID: <aba2bf95-836e-444d-961d-0b2ac1fb415a@kernel.org>
Date: Tue, 28 Oct 2025 17:53:23 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Pavan Kondeti <pavan.kondeti@....qualcomm.com>,
 Hrishabh Rajput <hrishabh.rajput@....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>
Subject: Re: [PATCH v3] watchdog: Add driver for Gunyah Watchdog

On 28/10/2025 17:51, Dmitry Baryshkov wrote:
> On Tue, Oct 28, 2025 at 05:40:33PM +0100, Krzysztof Kozlowski wrote:
>> On 28/10/2025 17:33, Pavan Kondeti wrote:
>>> On Tue, Oct 28, 2025 at 05:17:44PM +0100, Krzysztof Kozlowski wrote:
>>>> On 28/10/2025 13:27, Pavan Kondeti wrote:
>>>>> On Tue, Oct 28, 2025 at 12:07:40PM +0100, Krzysztof Kozlowski wrote:
>>>>>> On 28/10/2025 12:04, Krzysztof Kozlowski wrote:
>>>>>>> On 28/10/2025 11:58, Hrishabh Rajput wrote:
>>>>>>>>
>>>>>>>> On 10/28/2025 3:10 PM, Krzysztof Kozlowski wrote:
>>>>>>>>> On 28/10/2025 10:35, Hrishabh Rajput via B4 Relay wrote:
>>>>>>>>>> +
>>>>>>>>>> +static int __init gunyah_wdt_init(void)
>>>>>>>>>> +{
>>>>>>>>>> +	struct arm_smccc_res res;
>>>>>>>>>> +	struct device_node *np;
>>>>>>>>>> +	int ret;
>>>>>>>>>> +
>>>>>>>>>> +	/* Check if we're running on a Qualcomm device */
>>>>>>>>>> +	np = of_find_compatible_node(NULL, NULL, "qcom,smem");
>>>>>>>>> I don't think you implemented my feedback. This again is executed on
>>>>>>>>> every platform, e.g. on Samsung, pointlessly.
>>>>>>>>>
>>>>>>>>> Implement previous feedback.
>>>>>>>>
>>>>>>>> Do you want us to add platform device from another driver which is 
>>>>>>>> probed only on Qualcomm devices (like socinfo from previous discussion) 
>>>>>>>> and get rid of the module init function entirely? As keeping anything in 
>>>>>>>> the module init will get it executed on all platforms.
>>>>>>>
>>>>>>> Instead of asking the same can you read previous discussion? What is
>>>>>>> unclear here:
>>>>>>> https://lore.kernel.org/all/3b901f9d-dbfa-4f93-a8d2-3e89bd9783c9@kernel.org/
>>>>>>> ?
>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> With this patch version, we have tried to reduce the code execution on 
>>>>>>>> non-Qualcomm devices (also tried the alternative as mentioned in the 
>>>>>>>> cover letter). Adding platform device from another driver as described 
>>>>>>>> above would eliminate it entirely, please let us know if you want us to 
>>>>>>>> do that.
>>>>>>>
>>>>>>> Why do I need to repeat the same as last time?
>>>>>>
>>>>>>
>>>>>> Now I see that you completely ignored previous discussion and sent THE
>>>>>> SAME approach.
>>>>>
>>>>> Our intention is not to waste reviewers time at all. It is just a
>>>>> misunderstanding on what your comment is about. Let me elaborate further
>>>>> not to defend our approach here but to get a clarity so that we don't
>>>>> end up in the same situation when v4 is posted.
>>>>>
>>>>> https://lore.kernel.org/all/b94d8ca3-af58-4a78-9a5a-12e3db0bf75f@kernel.org/ 
>>>>>
>>>>> You mentioned here
>>>>>
>>>>> ```
>>>>> To me socinfo feels even better. That way only, really only qcom devices
>>>>> will execute this SMC.
>>>>> ```
>>>>>
>>>>> We interpreted this comment as `avoid executing this SMC on non qcom
>>>>> devices`. That is exactly what we have done in the current patch. since
>>>>
>>>>
>>>> So where did you use socinfo? Point me to the code.
>>>>
>>>
>>> Okay, lets go a bit deep into the socinfo part. we have used
>>> `soc_device_match()` API to detect if the device is qcom (`family =
>>> Snapdragon`). It works. However, when we built both `socinfo` and
>>
>> socinfo driver. Read my first feedback:
>>
>>
>> "No, your hypervisor driver (which you have) should start the module via
>> adding platform/aux/something devices."
>>
>> And then I agreed if you start it from the socinfo driver.
> 
> I'd rather not tie this to socinfo. The socinfo is an optional driver,
> which is mainly used to provide debugfs entries. Watchdog is much more
> important. It should not be tied to debugfs-only entry.
> 

No problem. Choose whatever driver it is. The problem is that they did
not even implement that. They claimed they followed review but it is
100% ignored. Nothing got implemented and they send the same.

Best regards,
Krzysztof