linux-kernel - Re: [PATCH V2 2/2] platform/x86/intel/pmc/mtl: Put devices in D3 during resume

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Message-ID: <fa84b0098551123f34a68b3c0d9c7aa12f592bbf.camel@linux.intel.com>
Date:   Mon, 12 Jun 2023 11:02:38 -0700
From:   "David E. Box" <david.e.box@...ux.intel.com>
To:     Hans de Goede <hdegoede@...hat.com>, linux-kernel@...r.kernel.org,
        platform-driver-x86@...r.kernel.org
Cc:     markgross@...nel.org, irenic.rajneesh@...il.com,
        ilpo.jarvinen@...ux.intel.com, xi.pardee@...el.com,
        rajvi.jingar@...ux.intel.com
Subject: Re: [PATCH V2 2/2] platform/x86/intel/pmc/mtl: Put devices in D3
 during resume

Hi Hans,

On Mon, 2023-06-12 at 11:42 +0200, Hans de Goede wrote:
> Hi David,
> 
> On 6/8/23 01:38, David E. Box wrote:
> > An earlier commit placed some driverless devices in D3 during boot so that
> > they don't block package cstate entry on Meteor Lake. 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>
> 
> Thank you for your patch.
> 
> There is one thing which has me worried here:
> 
> What about when real proper drivers show up for these blocks?
> 
> I know that at least some people will likely be using the out of tree IPU6
> driver with the IPU block.
> 
> And having 2 different drivers poke at the hw state seems like a bad idea to
> me.
> 
> Maybe we can add a check if no driver is bound and only set the state to D3 if
> no driver is bound?

This check exists but is not shown in the patch. mtl_set_device_d3() gets the
device lock and checks to see if dev.driver is NULL before putting in D3. This
was checked with the GNA driver installed.

David

> 
> Regards,
> 
> Hans
> 
> 
> 
> > ---
> > 
> > V2 - rename mtl_fixup to mtl_d3_fixup. Call it from new mtl_resume
> >      function, followed by the common resume. Suggested by Ilpo.
> > 
> >  drivers/platform/x86/intel/pmc/mtl.c | 29 ++++++++++++++++++++--------
> >  1 file changed, 21 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/platform/x86/intel/pmc/mtl.c
> > b/drivers/platform/x86/intel/pmc/mtl.c
> > index e8cc156412ce..2b00ad9da621 100644
> > --- a/drivers/platform/x86/intel/pmc/mtl.c
> > +++ b/drivers/platform/x86/intel/pmc/mtl.c
> > @@ -68,16 +68,29 @@ static void mtl_set_device_d3(unsigned int device)
> >         }
> >  }
> >  
> > -void mtl_core_init(struct pmc_dev *pmcdev)
> > +/*
> > + * Set power state of select devices that do not have drivers to D3
> > + * so that they do not block Package C entry.
> > + */
> > +static void mtl_d3_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.
> > -        */
> >         mtl_set_device_d3(MTL_GNA_PCI_DEV);
> >         mtl_set_device_d3(MTL_IPU_PCI_DEV);
> >         mtl_set_device_d3(MTL_VPU_PCI_DEV);
> >  }
> > +
> > +static int mtl_resume(struct pmc_dev *pmcdev)
> > +{
> > +       mtl_d3_fixup();
> > +       return pmc_core_resume_common(pmcdev);
> > +}
> > +
> > +void mtl_core_init(struct pmc_dev *pmcdev)
> > +{
> > +       pmcdev->map = &mtl_reg_map;
> > +       pmcdev->core_configure = mtl_core_configure;
> > +
> > +       mtl_d3_fixup();
> > +
> > +       pmcdev->resume = mtl_resume;
> > +}
>