Unverified Commit 7a797cc9 authored by David E. Box's avatar David E. Box Committed by Ilpo Järvinen
Browse files

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



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: default avatarDavid E. Box <david.e.box@linux.intel.com>
Reviewed-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20241017210439.3449324-2-david.e.box@linux.intel.com


Reviewed-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
parent 9fe43c80

drivers/platform/x86/intel/pmc/cnp.c

+53 −0
Original line number Diff line number Diff line
@@ -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);