tools/power turbostat: Fix missing SYS_LPI counter on some Chromebooks
authorLen Brown <len.brown@intel.com>
Thu, 19 Mar 2020 22:26:05 +0000 (18:26 -0400)
committerLen Brown <len.brown@intel.com>
Fri, 20 Mar 2020 04:32:28 +0000 (00:32 -0400)
Some Chromebook BIOS' do not export an ACPI LPIT, which is how
Linux finds the residency counter for CPU and SYSTEM low power states,
that is exports in /sys/devices/system/cpu/cpuidle/*residency_us

When these sysfs attributes are missing, check the debugfs attrubte
from the pmc_core driver, which accesses the same counter value.

Signed-off-by: Len Brown <len.brown@intel.com>
tools/power/x86/turbostat/turbostat.c

index 761146c..3ecbf70 100644 (file)
@@ -304,6 +304,10 @@ int *irqs_per_cpu;         /* indexed by cpu_num */
 
 void setup_all_buffers(void);
 
+char *sys_lpi_file;
+char *sys_lpi_file_sysfs = "/sys/devices/system/cpu/cpuidle/low_power_idle_system_residency_us";
+char *sys_lpi_file_debugfs = "/sys/kernel/debug/pmc_core/slp_s0_residency_usec";
+
 int cpu_is_not_present(int cpu)
 {
        return !CPU_ISSET_S(cpu, cpu_present_setsize, cpu_present_set);
@@ -2916,8 +2920,6 @@ int snapshot_gfx_mhz(void)
  *
  * record snapshot of
  * /sys/devices/system/cpu/cpuidle/low_power_idle_cpu_residency_us
- *
- * return 1 if config change requires a restart, else return 0
  */
 int snapshot_cpu_lpi_us(void)
 {
@@ -2941,17 +2943,14 @@ int snapshot_cpu_lpi_us(void)
 /*
  * snapshot_sys_lpi()
  *
- * record snapshot of
- * /sys/devices/system/cpu/cpuidle/low_power_idle_system_residency_us
- *
- * return 1 if config change requires a restart, else return 0
+ * record snapshot of sys_lpi_file
  */
 int snapshot_sys_lpi_us(void)
 {
        FILE *fp;
        int retval;
 
-       fp = fopen_or_die("/sys/devices/system/cpu/cpuidle/low_power_idle_system_residency_us", "r");
+       fp = fopen_or_die(sys_lpi_file, "r");
 
        retval = fscanf(fp, "%lld", &cpuidle_cur_sys_lpi_us);
        if (retval != 1) {
@@ -4946,10 +4945,16 @@ void process_cpuid()
        else
                BIC_NOT_PRESENT(BIC_CPU_LPI);
 
-       if (!access("/sys/devices/system/cpu/cpuidle/low_power_idle_system_residency_us", R_OK))
+       if (!access(sys_lpi_file_sysfs, R_OK)) {
+               sys_lpi_file = sys_lpi_file_sysfs;
                BIC_PRESENT(BIC_SYS_LPI);
-       else
+       } else if (!access(sys_lpi_file_debugfs, R_OK)) {
+               sys_lpi_file = sys_lpi_file_debugfs;
+               BIC_PRESENT(BIC_SYS_LPI);
+       } else {
+               sys_lpi_file_sysfs = NULL;
                BIC_NOT_PRESENT(BIC_SYS_LPI);
+       }
 
        if (!quiet)
                decode_misc_feature_control();