linux-kernel - Re: [PATCH 2/2] platform/x86/intel/pmc/mtl: Put devices in D3 during resume

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Date:   Mon, 05 Jun 2023 07:52:31 -0700
From:   "David E. Box" <david.e.box@...ux.intel.com>
To:     Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc:     irenic.rajneesh@...il.com, hdegoede@...hat.com,
        markgross@...nel.org, platform-driver-x86@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] platform/x86/intel/pmc/mtl: Put devices in D3
 during resume

On Mon, 2023-06-05 at 14:59 +0300, Ilpo Järvinen wrote:
> On Fri, 2 Jun 2023, David E. Box wrote:
> 
> > An earlier commit placed some driverless devices in D3 during boot so that
> > they don't block package cstate entry. Also place these devices in D3 after
> > resume from suspend.
> > 
> > Fixes: 336ba968d3e3 ("platform/x86/intel/pmc/mtl: Put GNA/IPU/VPU devices in
> > D3")
> > Signed-off-by: David E. Box <david.e.box@...ux.intel.com>
> > ---
> >  drivers/platform/x86/intel/pmc/mtl.c | 15 +++++++++++----
> >  1 file changed, 11 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/platform/x86/intel/pmc/mtl.c
> > b/drivers/platform/x86/intel/pmc/mtl.c
> > index e8cc156412ce..d87c4597c6d4 100644
> > --- a/drivers/platform/x86/intel/pmc/mtl.c
> > +++ b/drivers/platform/x86/intel/pmc/mtl.c
> > @@ -68,11 +68,8 @@ static void mtl_set_device_d3(unsigned int device)
> >         }
> >  }
> >  
> > -void mtl_core_init(struct pmc_dev *pmcdev)
> > +static void mtl_fixup(void)
> >  {
> > -       pmcdev->map = &mtl_reg_map;
> > -       pmcdev->core_configure = mtl_core_configure;
> > -
> >         /*
> >          * Set power state of select devices that do not have drivers to D3
> >          * so that they do not block Package C entry.
> > @@ -81,3 +78,13 @@ void mtl_core_init(struct pmc_dev *pmcdev)
> >         mtl_set_device_d3(MTL_IPU_PCI_DEV);
> >         mtl_set_device_d3(MTL_VPU_PCI_DEV);
> 
> I'd prefer the function be called something related to d3 / power state / 
> or some along those lines rather than something obscure such as 
> mtl_fixup(). And you can move the comment to be a function comment now.

Okay.

> 
> >  }
> > +
> > +void mtl_core_init(struct pmc_dev *pmcdev)
> > +{
> > +       pmcdev->map = &mtl_reg_map;
> > +       pmcdev->core_configure = mtl_core_configure;
> > +
> > +       mtl_fixup();
> > +
> > +       pmcdev->resume_fixup = mtl_fixup;
> 
> I'm a bit on the edge here whether this is a good approach in long-term or 
> if it would be better to just provide a way for the platform file to 
> replace entire .resume() (for this task it's obviously enough but it 
> feels a bit hacky to hook into one fixed place on resume path).
> 
> static __maybe_unused int pmc_core_resume(struct device *dev)
> {
>         if (pmcdev->resume)
>                 return pmcdev->resume();
>         else
>                 return pmc_core_resume_common();
> }
> 
> where pmc_core_resume_common() contains the current pmc_core_resume() 
> contents.
> 
> mtl_resume() would just call the d3 func and the common resume functions.

Yeah, makes sense. There are several conditional tasks in the current resume
code, so trying to have a fixed place in there to call a platform specific
workaround may not be possible if we need to use this again for a different
reason.

David

> 
>