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SubjectRe: [PATCH] cpufreq: arm_big_little: fix frequency check when bL switcher is active
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On 13/10/15 08:19, Jon Medhurst (Tixy) wrote:
> On Mon, 2015-10-12 at 14:20 +0100, Sudeep Holla wrote:
>>
>> On 08/10/15 10:23, Jon Medhurst (Tixy) wrote:
>> [...]
>>
>>> diff --git a/drivers/cpufreq/arm_big_little.c b/drivers/cpufreq/arm_big_little.c
>>> index f1e42f8..59115a4 100644
>>> --- a/drivers/cpufreq/arm_big_little.c
>>> +++ b/drivers/cpufreq/arm_big_little.c
>>> @@ -149,6 +149,18 @@ 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 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 (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 +201,6 @@ 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;
>>> }
>>>
>>>
>>>
>>>
>>
>> The above change looks good to me but with minor nit. You can get rid of
>> if(!ret) check if you move the hunk after if (WARN_ON(ret))
>
> But then we wouldn't get the WARN_ON and pr_err triggered when we detect
> the clock rate isn't set, which surely is half the reason for the check
> in the first place?
>

Not sure if I understand what you mean or may be I was not clear, so
thought I will put the delta here. Let me know if and how its still a
problem.

Regards,
Sudeep

-->8

diff --git i/drivers/cpufreq/arm_big_little.c
w/drivers/cpufreq/arm_big_little.c
index f1e42f8ce0fc..05e850f80f39 100644
--- i/drivers/cpufreq/arm_big_little.c
+++ w/drivers/cpufreq/arm_big_little.c
@@ -164,6 +164,16 @@ bL_cpufreq_set_rate(u32 cpu, u32 old_cluster, u32
new_cluster, u32 rate)

mutex_unlock(&cluster_lock[new_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;
+
/* Recalc freq for old cluster when switching clusters */
if (old_cluster != new_cluster) {
pr_debug("%s: cpu: %d, old cluster: %d, new cluster: %d\n",
@@ -189,15 +199,6 @@ 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;
}

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