linux-kernel - Re: [PATCH] drm/panthor: attach the driver's multiple power domains

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Message-ID: <aOfPaQWIVzMaWlSl@oss.nxp.com>
Date: Thu, 9 Oct 2025 23:06:17 +0800
From: Rain Yang <jiyu.yang@....nxp.com>
To: Boris Brezillon <boris.brezillon@...labora.com>
Cc: airlied@...il.com, boris.brezillon@...labora.com,
	dri-devel@...ts.freedesktop.org, imx@...ts.linux.dev,
	linux-kernel@...r.kernel.org, liviu.dudau@....com,
	maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
	prabhu.sundararaj@....com, simona@...ll.ch, steven.price@....com,
	tzimmermann@...e.de, xianzhong.li@....com
Subject: Re: [PATCH] drm/panthor: attach the driver's multiple power domains

On Thu, Oct 09, 2025 at 04:09:29PM +0200, Boris Brezillon wrote:
>On Thu, 9 Oct 2025 16:08:20 +0200
>Boris Brezillon <boris.brezillon@...labora.com> wrote:
>
>> On Thu,  9 Oct 2025 22:00:39 +0800
>> Rain Yang <jiyu.yang@....nxp.com> wrote:
>> 
>> > From: Rain Yang <jiyu.yang@....com>
>> > 
>> > Some platforms, such as i.MX95, utilize multiple power domains that need
>> > to be attached explicitly. This patch ensures that the driver properly
>> > attaches all available power domains using devm_pm_domain_attach_list().
>> > 
>> > Signed-off-by: Prabhu Sundararaj <prabhu.sundararaj@....com>
>> > Signed-off-by: Rain Yang <jiyu.yang@....com>
>> > ---
>> >  drivers/gpu/drm/panthor/panthor_device.c | 6 ++++++
>> >  drivers/gpu/drm/panthor/panthor_device.h | 2 ++
>> >  2 files changed, 8 insertions(+)
>> > 
>> > diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
>> > index f0b2da5b2b96..6f40d053b16c 100644
>> > --- a/drivers/gpu/drm/panthor/panthor_device.c
>> > +++ b/drivers/gpu/drm/panthor/panthor_device.c
>> > @@ -218,6 +218,12 @@ int panthor_device_init(struct panthor_device *ptdev)
>> >  	if (ret)
>> >  		return ret;
>> >  
>> > +	ret = devm_pm_domain_attach_list(ptdev->base.dev, NULL, &ptdev->pd_list);
>> > +	if (ret < 0) {
>> > +		drm_err(&ptdev->base, "attach power domains failed, ret=%d", ret);
>> > +		return ret;
>> > +	}
>> > +
>> >  	ret = panthor_devfreq_init(ptdev);
>> >  	if (ret)
>> >  		return ret;
>> > diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
>> > index 4fc7cf2aeed5..5ecb541ec67b 100644
>> > --- a/drivers/gpu/drm/panthor/panthor_device.h
>> > +++ b/drivers/gpu/drm/panthor/panthor_device.h
>> > @@ -196,6 +196,8 @@ struct panthor_device {
>> >  		/** @recovery_needed: True when a resume attempt failed. */
>> >  		atomic_t recovery_needed;
>> >  	} pm;  
>> 
>> Add a blank line here.
>> 
>> > +	/** @pm: Power management related data. */
>
>Also, the comment is wrong, and it would probably make sense to move
>that to the pm sub-struct since this is PM related.
thanks, will fix it next version.
>
>> > +	struct dev_pm_domain_list  *pd_list;
>> >    
>> 
>> Do we even need to keep the pd_list in panthor_device if we don't do
>> anything with it?
The second power domain is typically used for frequency scaling. The driver
works fine when there's only one single power domain. That said, I will update
the implementation to attach multiple power domains only when the domain count
is greater than one.
>> 
>> >  	/** @profile_mask: User-set profiling flags for job accounting. */
>> >  	u32 profile_mask;  
>> 
>