On 02-10-15, 18:38, Jon Medhurst (Tixy) wrote:
> 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 comment for the test indicates that it is temporary and limited
> lets not bother fixing it to work when the bL switcher is active and
> instead just bypass the test in that case.
>
> Fixes: 0a95e630b49a ("cpufreq: arm_big_little: check if the frequency is set
> correctly")
>
> Signed-off-by: Jon Medhurst <t...@linaro.org>
> ---
> drivers/cpufreq/arm_big_little.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
And why not fix it properly by doing this:
diff --git a/drivers/cpufreq/arm_big_little.c b/drivers/cpufreq/arm_big_little.c
index f1e42f8ce0fc..5b36657a76d6 100644
--- a/drivers/cpufreq/arm_big_little.c
+++ b/drivers/cpufreq/arm_big_little.c
@@ -128,7 +128,7 @@ static unsigned int bL_cpufreq_get_rate(unsigned int cpu)
static unsigned int
bL_cpufreq_set_rate(u32 cpu, u32 old_cluster, u32 new_cluster, u32 rate)
{
- u32 new_rate, prev_rate;
+ u32 new_rate, prev_rate, target_rate;
int ret;
bool bLs = is_bL_switching_enabled();
@@ -140,9 +140,11 @@ bL_cpufreq_set_rate(u32 cpu, u32 old_cluster, u32
new_cluster, u32 rate)
per_cpu(physical_cluster, cpu) = new_cluster;
new_rate = find_cluster_maxfreq(new_cluster);
+ target_rate = new_rate;
new_rate = ACTUAL_FREQ(new_cluster, new_rate);
} else {
new_rate = rate;
+ target_rate = new_rate;
}
pr_debug("%s: cpu: %d, old cluster: %d, new cluster: %d, freq: %d\n",
@@ -196,7 +198,7 @@ bL_cpufreq_set_rate(u32 cpu, u32 old_cluster, u32
new_cluster, u32 rate)
* 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)
+ if (bL_cpufreq_get_rate(cpu) != target_rate)
return -EIO;
return 0;
}
--
viresh
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