Message-ID: <98397a59-8ef2-4202-ae41-015c895d6bce@oss.qualcomm.com>
Date: Wed, 28 Jan 2026 10:45:42 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Gaurav Kohli <gaurav.kohli@....qualcomm.com>,
        Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Bjorn Andersson <andersson@...nel.org>, mathieu.poirier@...aro.org,
        robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
        rafael@...nel.org, daniel.lezcano@...aro.org, rui.zhang@...el.com,
        lukasz.luba@....com, konradybcio@...nel.org, amitk@...nel.org,
        mani@...nel.org, casey.connolly@...aro.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v1 2/8] remoteproc: qcom: probe all child devices

On 1/28/26 10:39 AM, Gaurav Kohli wrote:
> 
> On 1/27/2026 10:11 PM, Dmitry Baryshkov wrote:
>> On Tue, Jan 27, 2026 at 09:42:10PM +0530, Gaurav Kohli wrote:
>>> On 1/24/2026 12:33 AM, Dmitry Baryshkov wrote:
>>>> On Fri, Jan 23, 2026 at 07:23:39PM +0530, Gaurav Kohli wrote:
>>>>> On 1/8/2026 12:37 PM, Gaurav Kohli wrote:
>>>>>> On 1/3/2026 8:26 PM, Bjorn Andersson wrote:
>>>>>>> On Tue, Dec 23, 2025 at 06:02:21PM +0530, Gaurav Kohli wrote:
>>>>>>>> From: Casey Connolly <casey.connolly@...aro.org>
>>>>>>>>
>>>>>>>> Generalise the qcom,bam-dmux child node support by probing all
>>>>>>>> remoteproc children with of_platform_populate(). This will be used to
>>>>>>>> enable support for devices which are best represented as
>>>>>>>> subnodes of the
>>>>>>>> remoteproc, such as those representing QMI clients.
>>>>>>> Please flip this around, start with the description of the problem
>>>>>>> you're trying to solve.
>>>>>>>
>>>>>>>> Signed-off-by: Casey Connolly <casey.connolly@...aro.org>
>>>>>>> This must have your signed-off-by, where you certifies the origin of
>>>>>>> this patch.
>>>>>>>
>>>>>>>> ---
>>>>>>>>     drivers/remoteproc/qcom_q6v5.c     | 4 ++++
>>>>>>>>     drivers/remoteproc/qcom_q6v5_mss.c | 8 --------
>>>>>>>>     2 files changed, 4 insertions(+), 8 deletions(-)
>>>>>>>>
>>>>>>>> diff --git a/drivers/remoteproc/qcom_q6v5.c
>>>>>>>> b/drivers/remoteproc/qcom_q6v5.c
>>>>>>>> index 58d5b85e58cd..a02839c7ed8c 100644
>>>>>>>> --- a/drivers/remoteproc/qcom_q6v5.c
>>>>>>>> +++ b/drivers/remoteproc/qcom_q6v5.c
>>>>>>>> @@ -6,6 +6,7 @@
>>>>>>>>      * Copyright (C) 2014 Sony Mobile Communications AB
>>>>>>>>      * Copyright (c) 2012-2013, The Linux Foundation. All rights
>>>>>>>> reserved.
>>>>>>>>      */
>>>>>>>> +#include <linux/of_platform.h>
>>>>>>>>     #include <linux/kernel.h>
>>>>>>>>     #include <linux/platform_device.h>
>>>>>>>>     #include <linux/interconnect.h>
>>>>>>>> @@ -351,6 +352,8 @@ int qcom_q6v5_init(struct qcom_q6v5 *q6v5,
>>>>>>>> struct platform_device *pdev,
>>>>>>>>             return dev_err_probe(&pdev->dev, PTR_ERR(q6v5->path),
>>>>>>>>                          "failed to acquire interconnect path\n");
>>>>>>>>     +    of_platform_populate(q6v5->dev->of_node, NULL, NULL, q6v5->dev);
>>>>>>> There are other child nodes here, in particular the GLINK and SMD edges.
>>>>>>> Do we really want platform_devices registered for them?
>>>>>>>
>>>>>>> Regards,
>>>>>>> Bjorn
>>>>>> thanks for pointing this, can you please suggest the right approach.
>>>>>>
>>>>>> This should not impact glink, as that is registering as rproc sub node,
>>>>>> And we need rproc cooling as child node
>>>>>>
>>>>>> of remote proc subsytem to create probe dependency only.
>>>>>>
>>>>>>
>>>>>> Can we do platform populate for specific child, would that be right
>>>>>> approach. or we should create rproc cooling as independent of parent ?
>>>>>>
>>>>> HI Bjorn,
>>>>>
>>>>> I’d like to highlight the impact and details of placement of remoteproc
>>>>> cooling dt node:
>>>>>
>>>>>
>>>>> ->As a child of the remote proc subsystem node:
>>>>>       In this configuration, the cooling device will only be probed once the
>>>>> corresponding remote proc subsystem itself is probed.
>>>>>
>>>>> ->Outside the remote proc subsystem, may be part of soc node:
>>>>>       In this setup, the cooling device will be probed independently. It will
>>>>> wait until the remoteproc subsystem is brought up
>>>>>       before completing cooling registration.
>>>>>       The drawback here is that if the parent remoteproc subsystem is
>>>>> disabled, the cooling device will still undergo an
>>>>>       unnecessary probe, even though it cannot be registered.
>>>> Bjorns question was different. It wasn't about pushing cooling device
>>>> outside of the remoteproc node. It is about not registering the devices.
>>>>
>>>> Can we follow the approach outlined by qcom_add_smd_subdev() /
>>>> qcom_add_glink_subdev()?
>>>
>>> Hi Dmitry,
>>>
>>> Thanks for the review. Since the remoteproc cooling is a QMI-based driver,
>>> it will receive the
>>> subsystem up notification directly. Therefore, there’s no need to make it a
>>> subdev node or
>>> tie it into the init/reset sequence of remoteproc subsytem.
>> But you've added a subnode for it (and we are discussing exactly
>> of_platform_populate()) call. So, you are tying it to the remoteproc
>> device lifecycle instead of the remoteproc subsys, which seems strange
>> to me. There is no cooling device if the DSP is not running.
> 
> 
> For the cooling feature, we don’t need to define it as a subnode. The cooling subsystem becomes relevant only
> after the remote subsystem is up, at which point it will receive add/delete notifications from the QMI server.
> 
> 
> If child nodes must be modeled as subnodes for rproc, we can move the CDSP TMD out of the remoteproc and add in soc.
> Is there currently a way for the remoteproc core layer to call of_platform_populate() without requiring a subnode?

I think the question is "why can't you register the remoteproc device
as a cooling_device, with perhaps #cooling-cells = <1>; instead of
any form of children?"

Konrad

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