intel_pstate: Fix setting VID

Commit 21855ff5 (intel_pstate: Set turbo VID for BayTrail) introduced
setting the turbo VID which is required to prevent a machine check on
some Baytrail SKUs under heavy graphics based workloads.  The
docmumentation update that brought the requirement to light also
changed the bit mask used for enumerating P state and VID values from
0x7f to 0x3f.

This change returns the mask value to 0x7f.

Tested with the Intel NUC DN2820FYK,
BIOS version FYBYT10H.86A.0034.2014.0513.1413 with v3.16-rc1 and
v3.14.8 kernel versions.

Fixes: 21855ff5 (intel_pstate: Set turbo VID for BayTrail)
Link: https://bugzilla.kernel.org/show_bug.cgi?id=77951
Reported-and-tested-by: Rune Reterson <rune@megahurts.dk>
Reported-and-tested-by: Eric Eickmeyer <erich@ericheickmeyer.com>
Cc: 3.13+ <stable@vger.kernel.org>  # 3.13+
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 924bb2d42b1c..74376d615eca 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -357,21 +357,21 @@ static int byt_get_min_pstate(void)
 {
         u64 value;
         rdmsrl(BYT_RATIOS, value);
-        return (value >> 8) & 0x3F;
+        return (value >> 8) & 0x7F;
 }
 
 static int byt_get_max_pstate(void)
 {
         u64 value;
         rdmsrl(BYT_RATIOS, value);
-        return (value >> 16) & 0x3F;
+        return (value >> 16) & 0x7F;
 }
 
 static int byt_get_turbo_pstate(void)
 {
         u64 value;
         rdmsrl(BYT_TURBO_RATIOS, value);
-        return value & 0x3F;
+        return value & 0x7F;
 }
 
 static void byt_set_pstate(struct cpudata *cpudata, int pstate)
@@ -405,8 +405,8 @@ static void byt_get_vid(struct cpudata *cpudata)
 
 
         rdmsrl(BYT_VIDS, value);
-        cpudata->vid.min = int_tofp((value >> 8) & 0x3f);
-        cpudata->vid.max = int_tofp((value >> 16) & 0x3f);
+        cpudata->vid.min = int_tofp((value >> 8) & 0x7f);
+        cpudata->vid.max = int_tofp((value >> 16) & 0x7f);
         cpudata->vid.ratio = div_fp(
                 cpudata->vid.max - cpudata->vid.min,
                 int_tofp(cpudata->pstate.max_pstate -