Messages in this thread Patch in this message | | | Date | Fri, 22 Nov 2013 12:33:32 +0530 | From | viresh kumar <> | Subject | Re: [PATCH] cpufreq: Make sure CPU is running on a freq from freq-table |
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On Thursday 21 November 2013 12:39 PM, Viresh Kumar wrote: > Sometimes boot loaders set CPU frequency to a value outside of frequency table > present with cpufreq core. In such cases CPU might be unstable if it has to run > on that frequency for long duration of time and so its better to set it to a > frequency which is specified in freq-table. This also makes cpufreq stats > inconsistent as cpufreq-stats would fail to register because current frequency > of CPU isn't found in freq-table. > > Because we don't want this change to effect boot process badly, we go for the > next freq which is >= policy->cur ('cur' must be set by now, otherwise we will > end up setting freq to lowest of the table as 'cur' is initialized to zero). > > In case where CPU is already running on one of the frequencies present in > freq-table, this would turn into a dummy call as __cpufreq_driver_target() would > return early. > > Reported-by: Carlos Hernandez <ceh@ti.com> > Reported-by: Nishanth Menon <nm@ti.com> > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Copying another mail from Nishant here to get my cc'list back..
On Friday 22 November 2013 05:12 AM, Nishanth Menon wrote: > I gave this a quick run on my 3.12 kernel: > http://pastebin.mozilla.org/3649730 is what I applied and output > http://pastebin.mozilla.org/3649729 > > I need to see what I might have mucked up.. or see if I can test this > on 3.13 master on a different board (since OMAP5 wont boot in master > without clock dts nodes :()..
This happened because of common sense, which was missing in my patch :)
Try this over existing patch:
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 6e8b226..e403388 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1126,13 +1126,19 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif, * In case where CPU is already running on one of the frequencies * present in freq-table, this would turn into a dummy call as * __cpufreq_driver_target() would return early. + * + * We are passing target-freq as "policy->cur - 1" otherwise + * __cpufreq_driver_target() would simply fail, as policy->cur will be + * equal to target-freq. */ if (has_target()) { - ret = __cpufreq_driver_target(policy, policy->cur, + ret = __cpufreq_driver_target(policy, policy->cur - 1, CPUFREQ_RELATION_L); - if (ret) + if (ret) { pr_err("%s: Unable to set frequency from table: %d\n", __func__, ret); + goto err_out_unregister; + } }
/* related cpus should atleast have policy->cpus */
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