linux-kernel - [PATCH 3.19.y-ckt 032/251] intel_pstate: set BYT MSR with wrmsrl_on

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Message-Id: <1437008972-9140-33-git-send-email-kamal@canonical.com>
Date:	Wed, 15 Jul 2015 18:05:53 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Joe Konno <joe.konno@...el.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 032/251] intel_pstate: set BYT MSR with wrmsrl_on_cpu()

3.19.8-ckt4 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Joe Konno <joe.konno@...el.com>

commit 0dd23f94251f49da99a6cbfb22418b2d757d77d6 upstream.

Commit 007bea098b86 (intel_pstate: Add setting voltage value for
baytrail P states.) introduced byt_set_pstate() with the assumption that
it would always be run by the CPU whose MSR is to be written by it.  It
turns out, however, that is not always the case in practice, so modify
byt_set_pstate() to enforce the MSR write done by it to always happen on
the right CPU.

Fixes: 007bea098b86 (intel_pstate: Add setting voltage value for baytrail P states.)
Signed-off-by: Joe Konno <joe.konno@...el.com>
Acked-by: Kristen Carlson Accardi <kristen@...ux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/cpufreq/intel_pstate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 742eefb..c37c895 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -497,7 +497,7 @@ static void byt_set_pstate(struct cpudata *cpudata, int pstate)
 
 	val |= vid;
 
-	wrmsrl(MSR_IA32_PERF_CTL, val);
+	wrmsrl_on_cpu(cpudata->cpu, MSR_IA32_PERF_CTL, val);
 }
 
 #define BYT_BCLK_FREQS 5
-- 
1.9.1

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