linux-kernel - Re: [PATCH v1 2/8] remoteproc: qcom: probe all child devices

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Message-ID: <74h7r3vsig3csejax3eu3uk53mdiimg2hjx7ntmmfrwdai6s3j@eiztghclfcvt>
Date: Fri, 23 Jan 2026 21:03:26 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Gaurav Kohli <gaurav.kohli@....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 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()?

-- 
With best wishes
Dmitry