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

["David E. Box" <david.e.box@xxxxxxxxxxxxxxx>]

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
+#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