From: "Rafael J. Wysocki" rafael.j.wysocki@intel.com
[ Upstream commit 43298db3009f06fe5c69e1ca8b6cfc2565772fa1 ]
After commit f6ebbcf08f37 ("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 --- drivers/cpufreq/intel_pstate.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index 5c41dc9aaa46d..be1a7bb0b4011 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -2098,9 +2098,15 @@ 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) {