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intel_idle: allow sparse sub-state numbering, for Bay Trail 

Like acpi_idle, intel_idle compared sub-state numbers
to the number of supported sub-states -- discarding
sub-states numbers that were numbered >= the number of states.

But some Bay Trail SOCs use sparse sub-state numbers,
so we can't make such a comparison if we are going
to access those states.

So now we simply check that _some_ sub-states are
supported for the given state, and assume that the
sub-state number in our driver is valid.

In practice, the driver is correct, and even if it were not,
the hardware clips invalid sub-state requests to valid ones.

No entries in the driver require this change,
but Bay Trail will need it.

Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Len Brown 2014-02-14 00:50:34 -05:00
parent 2194324d8b
commit 24bfa950f1
1 changed files with 4 additions and 5 deletions
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9
drivers/idle/intel_idle.c
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@ -584,7 +584,7 @@ static int __init intel_idle_cpuidle_driver_init(void)
drv->state_count = 1;
for (cstate = 0; cstate < CPUIDLE_STATE_MAX; ++cstate) {
int num_substates, mwait_hint, mwait_cstate, mwait_substate;
int num_substates, mwait_hint, mwait_cstate;
if (cpuidle_state_table[cstate].enter == NULL)
break;
@ -597,14 +597,13 @@ static int __init intel_idle_cpuidle_driver_init(void)
mwait_hint = flg2MWAIT(cpuidle_state_table[cstate].flags);
mwait_cstate = MWAIT_HINT2CSTATE(mwait_hint);
mwait_substate = MWAIT_HINT2SUBSTATE(mwait_hint);
/* does the state exist in CPUID.MWAIT? */
/* number of sub-states for this state in CPUID.MWAIT */
num_substates = (mwait_substates >> ((mwait_cstate + 1) * 4))
& MWAIT_SUBSTATE_MASK;
/* if sub-state in table is not enumerated by CPUID */
if ((mwait_substate + 1) > num_substates)
/* if NO sub-states for this state in CPUID, skip it */
if (num_substates == 0)
continue;
if (((mwait_cstate + 1) > 2) &&