Re: [PATCH] platform/x86/intel/pmc: Disable C1 auto-demotion during suspend

[David E. Box]

On Tue, 2024-10-01 at 22:11 -0500, Mario Limonciello wrote:
> On 10/1/2024 17:58, David E. Box wrote:
> > On some platforms, aggressive C1 auto-demotion may lead to failure to enter
> > the deepest C-state during suspend-to-idle, causing high power consumption.
> > To prevent this, disable C1 auto-demotion during suspend and re-enable on
> > resume.
> > 
> > Signed-off-by: David E. Box <david.e.box@xxxxxxxxxxxxxxx>
> > ---
> >   drivers/platform/x86/intel/pmc/arl.c |  3 +--
> >   drivers/platform/x86/intel/pmc/cnp.c | 28 +++++++++++++++++++++++++++-
> >   drivers/platform/x86/intel/pmc/lnl.c |  3 +--
> >   drivers/platform/x86/intel/pmc/mtl.c |  3 +--
> >   4 files changed, 30 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/platform/x86/intel/pmc/arl.c
> > b/drivers/platform/x86/intel/pmc/arl.c
> > index e10527c4e3e0..05dec4f5019f 100644
> > --- a/drivers/platform/x86/intel/pmc/arl.c
> > +++ b/drivers/platform/x86/intel/pmc/arl.c
> > @@ -687,9 +687,8 @@ static void arl_d3_fixup(void)
> >   static int arl_resume(struct pmc_dev *pmcdev)
> >   {
> >   	arl_d3_fixup();
> > -	pmc_core_send_ltr_ignore(pmcdev, 3, 0);
> >   
> > -	return pmc_core_resume_common(pmcdev);
> > +	return cnl_resume(pmcdev);
> >   }
> >   
> >   int arl_core_init(struct pmc_dev *pmcdev)
> > diff --git a/drivers/platform/x86/intel/pmc/cnp.c
> > b/drivers/platform/x86/intel/pmc/cnp.c
> > index 513c02670c5a..5b8b3ac7f061 100644
> > --- a/drivers/platform/x86/intel/pmc/cnp.c
> > +++ b/drivers/platform/x86/intel/pmc/cnp.c
> > @@ -7,7 +7,8 @@
> >    * All Rights Reserved.
> >    *
> >    */
> > -
> > +#define DEBUG
> 
> Did you mean to pull this out before submitting?

Yep. Thanks.

> 
> > +#include <linux/suspend.h>
> >   #include "core.h"
> >   
> >   /* Cannon Lake: PGD PFET Enable Ack Status Register(s) bitmap */
> > @@ -206,8 +207,24 @@ const struct pmc_reg_map cnp_reg_map = {
> >   	.etr3_offset = ETR3_OFFSET,
> >   };
> >   
> > +
> > +static DEFINE_PER_CPU(u64, pkg_cst_config);
> > +
> >   void cnl_suspend(struct pmc_dev *pmcdev)
> >   {
> > +	if (!pm_suspend_via_firmware()) {
> > +		u64 val;
> > +		int cpunum;
> > +
> > +		for_each_online_cpu(cpunum) {
> > +			rdmsrl_on_cpu(cpunum, MSR_PKG_CST_CONFIG_CONTROL,
> > &val);
> > +			per_cpu(pkg_cst_config, cpunum) = val;
> > +			val &= ~NHM_C1_AUTO_DEMOTE;
> > +			wrmsrl_on_cpu(cpunum, MSR_PKG_CST_CONFIG_CONTROL,
> > val);
> > +			pr_debug("%s: cpu:%d cst %llx\n", __func__, cpunum,
> > val);
> > +		}
> > +	}
> > +
> >   	/*
> >   	 * Due to a hardware limitation, the GBE LTR blocks PC10
> >   	 * when a cable is attached. To unblock PC10 during suspend,
> > @@ -220,6 +237,15 @@ int cnl_resume(struct pmc_dev *pmcdev)
> >   {
> >   	pmc_core_send_ltr_ignore(pmcdev, 3, 0);
> >   
> > +	if (!pm_suspend_via_firmware()) {
> > +		int cpunum;
> > +
> > +		for_each_online_cpu(cpunum) {
> > +			pr_debug("%s: cpu:%d cst %llx\n", __func__, cpunum,
> > per_cpu(pkg_cst_config, cpunum));
> > +			wrmsrl_on_cpu(cpunum, MSR_PKG_CST_CONFIG_CONTROL,
> > per_cpu(pkg_cst_config, cpunum));
> > +		}
> > +	}
> > +
> >   	return pmc_core_resume_common(pmcdev);
> >   }
> >   
> > diff --git a/drivers/platform/x86/intel/pmc/lnl.c
> > b/drivers/platform/x86/intel/pmc/lnl.c
> > index e7a8077d1a3e..be029f12cdf4 100644
> > --- a/drivers/platform/x86/intel/pmc/lnl.c
> > +++ b/drivers/platform/x86/intel/pmc/lnl.c
> > @@ -546,9 +546,8 @@ static void lnl_d3_fixup(void)
> >   static int lnl_resume(struct pmc_dev *pmcdev)
> >   {
> >   	lnl_d3_fixup();
> > -	pmc_core_send_ltr_ignore(pmcdev, 3, 0);
> >   
> > -	return pmc_core_resume_common(pmcdev);
> > +	return cnl_resume(pmcdev);
> >   }
> >   
> >   int lnl_core_init(struct pmc_dev *pmcdev)
> > diff --git a/drivers/platform/x86/intel/pmc/mtl.c
> > b/drivers/platform/x86/intel/pmc/mtl.c
> > index 91f2fa728f5c..fc6a89b8979f 100644
> > --- a/drivers/platform/x86/intel/pmc/mtl.c
> > +++ b/drivers/platform/x86/intel/pmc/mtl.c
> > @@ -988,9 +988,8 @@ static void mtl_d3_fixup(void)
> >   static int mtl_resume(struct pmc_dev *pmcdev)
> >   {
> >   	mtl_d3_fixup();
> > -	pmc_core_send_ltr_ignore(pmcdev, 3, 0);
> >   
> > -	return pmc_core_resume_common(pmcdev);
> > +	return cnl_resume(pmcdev);
> >   }
> >   
> >   int mtl_core_init(struct pmc_dev *pmcdev)
>