| Message ID | 20241017210439.3449324-2-david.e.box@linux.intel.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
| Series | [V3,1/2] platform/x86/intel/pmc: Refactor platform resume functions to use cnl_resume() | expand |
On Thu, Oct 17, 2024 at 11:04 PM David E. Box <david.e.box@linux.intel.com> wrote: > > 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> > --- > V3 - Use s2idle wrapper function suggested by Rafael > - Use on_each_cpu() suggested by Ricardo Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > 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(+) > > diff --git a/drivers/platform/x86/intel/pmc/cnp.c b/drivers/platform/x86/intel/pmc/cnp.c > index 513c02670c5a..3eaad2a7ebf4 100644 > --- a/drivers/platform/x86/intel/pmc/cnp.c > +++ b/drivers/platform/x86/intel/pmc/cnp.c > @@ -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 > >
diff --git a/drivers/platform/x86/intel/pmc/cnp.c b/drivers/platform/x86/intel/pmc/cnp.c index 513c02670c5a..3eaad2a7ebf4 100644 --- a/drivers/platform/x86/intel/pmc/cnp.c +++ b/drivers/platform/x86/intel/pmc/cnp.c @@ -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);
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> --- 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(+)