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

[Mario Limonciello <mario.limonciello@amd.com>]

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@linux.intel.com>
> ---
>   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?

> +#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)