cpufreq: intel_pstate: Fix processing for turbo activation ratio

When the config TDP level is not nominal (level = 0), the MSR values for
reading level 1 and level 2 ratios contain power in low 14 bits and actual
ratio bits are at bits [23:16]. The current processing for level 1 and
level 2 is wrong as there is no shift done to get actual ratio.

Fixes: 6a35fc2d6c22 (cpufreq: intel_pstate: get P1 from TAR when available)
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: 4.4+ <stable@vger.kernel.org> # 4.4+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 30fe323c4551b4628de4c5878500d29eab8d57ca..f502d5b90c2537b88a86b5224f21d175556be744 100644 (file)
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -813,6 +813,11 @@ static int core_get_max_pstate(void)
                        if (err)
                                goto skip_tar;
 
+                       /* For level 1 and 2, bits[23:16] contain the ratio */
+                       if (tdp_ctrl)
+                               tdp_ratio >>= 16;
+
+                       tdp_ratio &= 0xff; /* ratios are only 8 bits long */
                        if (tdp_ratio - 1 == tar) {
                                max_pstate = tar;
                                pr_debug("max_pstate=TAC %x\n", max_pstate);