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List:       git-commits-head
Subject:    cpufreq: intel_pstate: Fix processing for turbo activation ratio
From:       "Linux Kernel Mailing List" <linux-kernel () vger ! kernel ! org>
Date:       2016-04-30 0:48:59
Message-ID: 20160430004859.C0C84660F84 () gitolite ! kernel ! org
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Web:        https://git.kernel.org/torvalds/c/1becf03545a0859ceaaf9e8c2d9861882a71cb01
Commit:     1becf03545a0859ceaaf9e8c2d9861882a71cb01
Parent:     94862a62dfe3ba1c7601115a2dc80721c5b256f0
Refname:    refs/heads/master
Author:     Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
AuthorDate: Fri Apr 22 19:53:59 2016 -0700
Committer:  Rafael J. Wysocki <rafael.j.wysocki@intel.com>
CommitDate: Mon Apr 25 23:39:09 2016 +0200

    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>
---
 drivers/cpufreq/intel_pstate.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 30fe323..f502d5b 100644
--- 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);
--
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