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author | Jon Medhurst \(Tixy\) <tixy@linaro.org> | 2015-10-21 10:55:33 +0100 |
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committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2015-11-02 01:58:27 +0100 |
commit | 14f1ba3af6209f0394192ef07fe2bd9bccdc755f (patch) | |
tree | 0441ad96036b06ea942e890b5d08a86947ba7f4a /drivers/cpufreq | |
parent | 3510fac4549201919c565250fdff5cfa63db9e86 (diff) | |
download | linux-stable-14f1ba3af6209f0394192ef07fe2bd9bccdc755f.tar.gz linux-stable-14f1ba3af6209f0394192ef07fe2bd9bccdc755f.tar.bz2 linux-stable-14f1ba3af6209f0394192ef07fe2bd9bccdc755f.zip |
cpufreq: arm_big_little: fix frequency check when bL switcher is active
The check for correct frequency being set in bL_cpufreq_set_rate is
broken when the big.LITTLE switcher is active, for two reasons.
1. The 'new_rate' variable gets overwritten before the test by the
code calculating the frequency of the old cluster.
2. The frequency returned by bL_cpufreq_get_rate will be the virtual
frequency, not the actual one the intended version of new_rate contains.
This means the function always returns an error causing an endless
stream of: "cpufreq: __target_index: Failed to change cpu frequency: -5"
As the intent is to check for errors that clk_set_rate doesn't report
lets move the check to immediately after that and directly use
clk_get_rate, rather than the arm_big_little helpers which only confuse
matters. Also, update the comment to be hopefully clearer about the
purpose of the code.
Fixes: 0a95e630b49a (cpufreq: arm_big_little: check if the frequency is set correctly)
Signed-off-by: Jon Medhurst <tixy@linaro.org>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Michael Turquette <mturquette@baylibre.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq')
-rw-r--r-- | drivers/cpufreq/arm_big_little.c | 22 |
1 files changed, 13 insertions, 9 deletions
diff --git a/drivers/cpufreq/arm_big_little.c b/drivers/cpufreq/arm_big_little.c index f1e42f8ce0fc..c5d256caa664 100644 --- a/drivers/cpufreq/arm_big_little.c +++ b/drivers/cpufreq/arm_big_little.c @@ -149,6 +149,19 @@ bL_cpufreq_set_rate(u32 cpu, u32 old_cluster, u32 new_cluster, u32 rate) __func__, cpu, old_cluster, new_cluster, new_rate); ret = clk_set_rate(clk[new_cluster], new_rate * 1000); + if (!ret) { + /* + * FIXME: clk_set_rate hasn't returned an error here however it + * may be that clk_change_rate failed due to hardware or + * firmware issues and wasn't able to report that due to the + * current design of the clk core layer. To work around this + * problem we will read back the clock rate and check it is + * correct. This needs to be removed once clk core is fixed. + */ + if (clk_get_rate(clk[new_cluster]) != new_rate * 1000) + ret = -EIO; + } + if (WARN_ON(ret)) { pr_err("clk_set_rate failed: %d, new cluster: %d\n", ret, new_cluster); @@ -189,15 +202,6 @@ bL_cpufreq_set_rate(u32 cpu, u32 old_cluster, u32 new_cluster, u32 rate) mutex_unlock(&cluster_lock[old_cluster]); } - /* - * FIXME: clk_set_rate has to handle the case where clk_change_rate - * can fail due to hardware or firmware issues. Until the clk core - * layer is fixed, we can check here. In most of the cases we will - * be reading only the cached value anyway. This needs to be removed - * once clk core is fixed. - */ - if (bL_cpufreq_get_rate(cpu) != new_rate) - return -EIO; return 0; } |