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From: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
To: rjw@rjwysocki.net, mroos@linux.ee, viresh.kumar@linaro.org
Cc: cpufreq@vger.kernel.org, linux-pm@vger.kernel.org,
	linux-kernel@vger.kernel.org, srivatsa.bhat@linux.vnet.ibm.com
Subject: [PATCH v2 4/5] cpufreq, powernow-k7: Fix double invocation of cpufreq_freq_transition_begin/end
Date: Tue, 29 Apr 2014 00:24:58 +0530	[thread overview]
Message-ID: <20140428185451.28755.11924.stgit@srivatsabhat.in.ibm.com> (raw)
In-Reply-To: <20140428185331.28755.899.stgit@srivatsabhat.in.ibm.com>

During frequency transitions, the cpufreq core takes the responsibility of
invoking cpufreq_freq_transition_begin() and cpufreq_freq_transition_end()
for those cpufreq drivers that define the ->target_index callback but don't
set the ASYNC_NOTIFICATION flag.

The powernow-k7 cpufreq driver falls under this category, but this driver was
invoking the _begin() and _end() APIs itself around frequency transitions,
which led to double invocation of the _begin() API. The _begin API makes
contending callers wait until the previous invocation is complete. Hence,
the powernow-k7 driver ended up waiting on itself, leading to system hangs
during boot.

Fix this by removing the calls to the _begin() and _end() APIs from the
powernow-k7 driver, since they rightly belong to the cpufreq core.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
---

 drivers/cpufreq/powernow-k7.c |    4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/cpufreq/powernow-k7.c b/drivers/cpufreq/powernow-k7.c
index f911645..e61e224 100644
--- a/drivers/cpufreq/powernow-k7.c
+++ b/drivers/cpufreq/powernow-k7.c
@@ -269,8 +269,6 @@ static int powernow_target(struct cpufreq_policy *policy, unsigned int index)
 
 	freqs.new = powernow_table[index].frequency;
 
-	cpufreq_freq_transition_begin(policy, &freqs);
-
 	/* Now do the magic poking into the MSRs.  */
 
 	if (have_a0 == 1)	/* A0 errata 5 */
@@ -290,8 +288,6 @@ static int powernow_target(struct cpufreq_policy *policy, unsigned int index)
 	if (have_a0 == 1)
 		local_irq_enable();
 
-	cpufreq_freq_transition_end(policy, &freqs, 0);
-
 	return 0;
 }
 


  parent reply	other threads:[~2014-04-28 18:54 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-28 18:53 [PATCH v2 0/5] Cpufreq frequency serialization fixes Srivatsa S. Bhat
2014-04-28 18:54 ` [PATCH v2 1/5] cpufreq, longhaul: Fix double invocation of cpufreq_freq_transition_begin/end Srivatsa S. Bhat
2014-04-28 18:54 ` [PATCH v2 2/5] cpufreq, powernow-k6: Fix incorrect comparison with max_multipler Srivatsa S. Bhat
2014-04-28 18:54 ` [PATCH v2 3/5] cpufreq, powernow-k6: Fix double invocation of cpufreq_freq_transition_begin/end Srivatsa S. Bhat
2014-04-28 18:54 ` Srivatsa S. Bhat [this message]
2014-04-28 18:55 ` [PATCH v2 5/5] cpufreq: Catch double invocations " Srivatsa S. Bhat
2014-04-29  4:51   ` Viresh Kumar
2014-04-29  4:55     ` Viresh Kumar
2014-04-29  6:16       ` Srivatsa S. Bhat
2014-04-29  6:49         ` Viresh Kumar
2014-04-29  7:35           ` Srivatsa S. Bhat
2014-04-29  8:04             ` Viresh Kumar
2014-04-29  8:10               ` Srivatsa S. Bhat
2014-04-29  6:08     ` Srivatsa S. Bhat
2014-04-28 20:57 ` [PATCH v2 0/5] Cpufreq frequency serialization fixes Meelis Roos
2014-04-28 23:47 ` Rafael J. Wysocki
2014-04-29  5:59   ` Srivatsa S. Bhat

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