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cpufreq: intel_pstate: Refuse to turn off with HWP enabled 

[ Upstream commit 43298db300 ]

After commit f6ebbcf08f ("cpufreq: intel_pstate: Implement passive
mode with HWP enabled") it is possible to change the driver status
to "off" via sysfs with HWP enabled, which effectively causes the
driver to unregister itself, but HWP remains active and it forces the
minimum performance, so even if another cpufreq driver is loaded,
it will not be able to control the CPU frequency.

For this reason, make the driver refuse to change the status to
"off" with HWP enabled.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Rafael J. Wysocki 2020-08-20 17:40:02 +02:00 committed by Greg Kroah-Hartman
parent b011e41a8e
commit 1f11694748
1 changed files with 9 additions and 3 deletions
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12
drivers/cpufreq/intel_pstate.c
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@ -2533,9 +2533,15 @@ static int intel_pstate_update_status(const char *buf, size_t size)
{
int ret;
if (size == 3 && !strncmp(buf, "off", size))
return intel_pstate_driver ?
intel_pstate_unregister_driver() : -EINVAL;
if (size == 3 && !strncmp(buf, "off", size)) {
if (!intel_pstate_driver)
return -EINVAL;
if (hwp_active)
return -EBUSY;
return intel_pstate_unregister_driver();
}
if (size == 6 && !strncmp(buf, "active", size)) {
if (intel_pstate_driver) {