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

David E. Box
2024-10-01T22:59:10Z

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
+#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)
--
2.43.0