platform/x86/intel/pmc: Refactor platform resume functions to use cnl_resume()

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 <[email protected]>

---
V3 - Use s2idle wrapper function suggested by Rafael
- Use on_each_cpu() suggested by Ricardo

V2 - Remove #define DEBUG
- Move refactor of cnl_resume() to separate patch
- Use smp_call_function() to disable and restore C1_AUTO_DEMOTE
- Add comment that the MSR is per core, not per package.
- Add comment that the online cpu mask remains unchanged during suspend due to frozen userspace.

 drivers/platform/x86/intel/pmc/cnp.c | 53 ++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

drivers/platform/x86/intel/pmc/cnp.c +53 -1

index 513c02670c5a..3eaad2a7ebf4 100644
@@ -8,6 +8,8 @@
  *
  */
 
+#include <linux/smp.h>
+#include <linux/suspend.h>
 #include "core.h"
 
 /* Cannon Lake: PGD PFET Enable Ack Status Register(s) bitmap */

@@ -206,8 +208,57 @@ const struct pmc_reg_map cnp_reg_map = {
        .etr3_offset = ETR3_OFFSET,
 };
 
+
+/*
+ * Disable C1 auto-demotion
+ *
+ * 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, we
+ * disable C1 auto-demotion during suspend and re-enable on resume.
+ *
+ * Note that, although MSR_PKG_CST_CONFIG_CONTROL has 'package' in its name, it
+ * is actually a per-core MSR on client platforms, affecting only a single CPU.
+ * Therefore, it must be configured on all online CPUs. The online cpu mask is
+ * unchanged during the phase of suspend/resume as user space is frozen.
+ */
+
+static DEFINE_PER_CPU(u64, pkg_cst_config);
+
+static void disable_c1_auto_demote(void *unused)
+{
+       int cpunum = smp_processor_id();
+       u64 val;
+
+       rdmsrl(MSR_PKG_CST_CONFIG_CONTROL, val);
+       per_cpu(pkg_cst_config, cpunum) = val;
+       val &= ~NHM_C1_AUTO_DEMOTE;
+       wrmsrl(MSR_PKG_CST_CONFIG_CONTROL, val);
+
+       pr_debug("%s: cpu:%d cst %llx\n", __func__, cpunum, val);
+}
+
+static void restore_c1_auto_demote(void *unused)
+{
+       int cpunum = smp_processor_id();
+
+       wrmsrl(MSR_PKG_CST_CONFIG_CONTROL, per_cpu(pkg_cst_config, cpunum));
+
+       pr_debug("%s: cpu:%d cst %llx\n", __func__, cpunum,
+                per_cpu(pkg_cst_config, cpunum));
+}
+
+static void s2idle_cpu_quirk(smp_call_func_t func)
+{
+       if (pm_suspend_via_firmware())
+               return;
+
+       on_each_cpu(func, NULL, true);
+}
+
 void cnl_suspend(struct pmc_dev *pmcdev)
 {
+       s2idle_cpu_quirk(disable_c1_auto_demote);
+
        /*
         * Due to a hardware limitation, the GBE LTR blocks PC10
         * when a cable is attached. To unblock PC10 during suspend,

@@ -218,6 +269,8 @@ void cnl_suspend(struct pmc_dev *pmcdev)
 
 int cnl_resume(struct pmc_dev *pmcdev)
 {
+       s2idle_cpu_quirk(restore_c1_auto_demote);
+
        pmc_core_send_ltr_ignore(pmcdev, 3, 0);
 
        return pmc_core_resume_common(pmcdev);
--

2.43.0

Several platform resume functions currently call pmc_core_send_ltr_ignore() and pmc_core_resume_common(), both of which are already called by cnl_resume(). Simplify the code by having these functions call cnl_resume() directly.

Signed-off-by David E. Box <[email protected]>

---
V3 - no change

V2 - New patch. Split from V1

 drivers/platform/x86/intel/pmc/arl.c | 3 +--
 drivers/platform/x86/intel/pmc/lnl.c | 3 +--
 drivers/platform/x86/intel/pmc/mtl.c | 3 +--
 3 files changed, 3 insertions(+), 6 deletions(-)

drivers/platform/x86/intel/pmc/arl.c +1 -2

index e10527c4e3e0..05dec4f5019f 100644
@@ -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)

drivers/platform/x86/intel/pmc/lnl.c +1 -2

index e7a8077d1a3e..be029f12cdf4 100644
@@ -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)

drivers/platform/x86/intel/pmc/mtl.c +1 -2

index 91f2fa728f5c..fc6a89b8979f 100644
@@ -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)

base-commit: 9852d85ec9d492ebef56dc5f229416c925758edc --
2.43.0

Several platform resume functions currently call pmc_core_send_ltr_ignore() and pmc_core_resume_common(), both of which are already called by cnl_resume(). Simplify the code by having these functions call cnl_resume() directly.