Messages in this thread | | | Date | Sun, 21 Jul 2019 20:40:37 -0400 | From | Sasha Levin <> | Subject | Re: [PATCH AUTOSEL 4.19 123/158] cpufreq: Don't skip frequency validation for has_target() drivers |
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On Tue, Jul 16, 2019 at 11:21:34AM +0200, Rafael J. Wysocki wrote: >On 7/15/2019 4:17 PM, Sasha Levin wrote: >>From: Viresh Kumar <viresh.kumar@linaro.org> >> >>[ Upstream commit 9801522840cc1073f8064b4c979b7b6995c74bca ] >> >>CPUFREQ_CONST_LOOPS was introduced in a very old commit from pre-2.6 >>kernel release by commit 6a4a93f9c0d5 ("[CPUFREQ] Fix 'out of sync' >>issue"). >> >>Basically, that commit does two things: >> >> - It adds the frequency verification code (which is quite similar to >> what we have today as well). >> >> - And it sets the CPUFREQ_CONST_LOOPS flag only for setpolicy drivers, >> rightly so based on the code we had then. The idea was to avoid >> frequency validation for setpolicy drivers as the cpufreq core doesn't >> know what frequency the hardware is running at and so no point in >> doing frequency verification. >> >>The problem happened when we started to use the same CPUFREQ_CONST_LOOPS >>flag for constant loops-per-jiffy thing as well and many has_target() >>drivers started using the same flag and unknowingly skipped the >>verification of frequency. There is no logical reason behind skipping >>frequency validation because of the presence of CPUFREQ_CONST_LOOPS >>flag otherwise. >> >>Fix this issue by skipping frequency validation only for setpolicy >>drivers and always doing it for has_target() drivers irrespective of >>the presence or absence of CPUFREQ_CONST_LOOPS flag. >> >>cpufreq_notify_transition() is only called for has_target() type driver >>and not for set_policy type, and the check is simply redundant. Remove >>it as well. >> >>Also remove () around freq comparison statement as they aren't required >>and checkpatch also warns for them. >> >>Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> >>Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> >>Signed-off-by: Sasha Levin <sashal@kernel.org> >>--- >> drivers/cpufreq/cpufreq.c | 13 +++++-------- >> 1 file changed, 5 insertions(+), 8 deletions(-) >> >>diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c >>index d3213594d1a7..80942ec34efd 100644 >>--- a/drivers/cpufreq/cpufreq.c >>+++ b/drivers/cpufreq/cpufreq.c >>@@ -321,12 +321,10 @@ static void cpufreq_notify_transition(struct cpufreq_policy *policy, >> * which is not equal to what the cpufreq core thinks is >> * "old frequency". >> */ >>- if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) { >>- if (policy->cur && (policy->cur != freqs->old)) { >>- pr_debug("Warning: CPU frequency is %u, cpufreq assumed %u kHz\n", >>- freqs->old, policy->cur); >>- freqs->old = policy->cur; >>- } >>+ if (policy->cur && policy->cur != freqs->old) { >>+ pr_debug("Warning: CPU frequency is %u, cpufreq assumed %u kHz\n", >>+ freqs->old, policy->cur); >>+ freqs->old = policy->cur; >> } >> for_each_cpu(freqs->cpu, policy->cpus) { >>@@ -1543,8 +1541,7 @@ static unsigned int __cpufreq_get(struct cpufreq_policy *policy) >> if (policy->fast_switch_enabled) >> return ret_freq; >>- if (ret_freq && policy->cur && >>- !(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) { >>+ if (has_target() && ret_freq && policy->cur) { >> /* verify no discrepancy between actual and >> saved value exists */ >> if (unlikely(ret_freq != policy->cur)) { > >This is not -stable material, please drop it.
I've dropped it, thanks!
-- Thanks, Sasha
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