ACPI, cpuidle: Clarify C-state description in sysfs

Add a new sysfs entry under cpuidle states. desc - can be used by driver to
communicate to userspace any specific information about the state.
This helps in identifying the exact hardware C-states behind the ACPI C-state
definition.

Idea is to export this through powertop, which will help to map the C-state
reported by powertop to actual hardware C-state.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
index 10b67170b133..8ca3557a6d59 100644
--- a/arch/x86/kernel/acpi/cstate.c
+++ b/arch/x86/kernel/acpi/cstate.c
@@ -126,6 +126,8 @@ int acpi_processor_ffh_cstate_probe(unsigned int cpu,
                 printk(KERN_DEBUG "Monitor-Mwait will be used to enter C-%d "
                        "state\n", cx->type);
         }
+        snprintf(cx->desc, ACPI_CX_DESC_LEN, "ACPI FFH INTEL MWAIT 0x%x",
+                 cx->address);
 
 out:
         set_cpus_allowed(current, saved_mask);