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

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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>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20241017210439.3449324-2-david.e.box@linux.intel.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
This commit is contained in:
David E. Box
2024-10-17 14:04:38 -07:00
committed by Ilpo Järvinen
parent 9fe43c8020
commit 7a797cc9f8
1 changed files with 53 additions and 0 deletions
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53
drivers/platform/x86/intel/pmc/cnp.c
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@@ -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);