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

[Rain Yang <jiyu.yang@oss.nxp.com>]

On Thu, Oct 09, 2025 at 05:23:20PM +0200, Boris Brezillon wrote:
>On Thu, 9 Oct 2025 23:06:17 +0800
>Rain Yang <jiyu.yang@oss.nxp.com> wrote:
>
>> 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@collabora.com> wrote:
>> >  
>> >> On Thu,  9 Oct 2025 22:00:39 +0800
>> >> Rain Yang <jiyu.yang@oss.nxp.com> wrote:
>> >>   
>> >> > From: Rain Yang <jiyu.yang@nxp.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@nxp.com>
>> >> > Signed-off-by: Rain Yang <jiyu.yang@nxp.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.
>
>That's not what I meant. What I mean is that the
>panthor_device::pd_list is never used, because the extra power domains
>get attached to the struct device directly, and the PM core
>automatically enables all PDs on resume and disable them on suspend.
>Because it's a devm_ function, you don't need it to detach the pd_list
>at ::remove() time either. TLDR; that means you can pass
>devm_pm_domain_attach_list() a local pd_list instead of ptdev->pd_list
>and you can thus drop panthor_device::pd_list altogether, I think.
>
>If you intend to use the pd_list for manual PD control in panthor in a
>follow-up patchset, this should be mentioned in the commit message.
thanks for your suggestion, pd_list will be allocated by devm_kmalloc.

I have not found a general solution to modify the frequency via SCMI perf
and OPP framework except the manual PD control, I'd appreciate it if
there is any idea.
>
>> >>   
>> >> >  	/** @profile_mask: User-set profiling flags for job accounting. */
>> >> >  	u32 profile_mask;    
>> >>   
>> >  
>