[PATCH] cpufreq: exynos: Broadcast frequency change notifications for all cores

On Thursday 31 of January 2013 20:22:50 Viresh Kumar wrote:

On 31 January 2013 20:15, Tomasz Figa [off-list ref] wrote:

quoted

On Thursday 31 of January 2013 09:50:37 Viresh Kumar wrote:

quoted

quoted

+               policy->shared_type = CPUFREQ_SHARED_TYPE_ANY;

I couldn't understand the use of this change. Can you please explain
?

All cores on Exynos SoCs share the same clock source, which means that
they all always run at the same frequency. So setting frequency on one
core sets the frequency on all cores and so it doesn't matter on which
core the frequency setting operation is done.

Great, that's like most other platforms and for this you just need to
set mask of all the possible cpus (online or offline) into policy->cpus

quoted

As you can see in include/linux/cpufreq.h:

#define CPUFREQ_SHARED_TYPE_ANY  (3) /* Freq can be set from any
dependent CPU*/

which basically tells (together with rest of the patch) the cpufreq
subsystem about what I wrote earlier.

I don't think so. Because i wasn't using it on my system and it was
working well.
Then i grepped it in kernel source

viresh at blr-linut-001:$ git grep shared_type drivers/cpufreq/
drivers/cpufreq/acpi-cpufreq.c: if (policy->shared_type !=
CPUFREQ_SHARED_TYPE_ANY)
drivers/cpufreq/acpi-cpufreq.c: policy->shared_type = perf->shared_type;
drivers/cpufreq/acpi-cpufreq.c: if (policy->shared_type ==
CPUFREQ_SHARED_TYPE_ALL ||
drivers/cpufreq/acpi-cpufreq.c:     policy->shared_type ==
CPUFREQ_SHARED_TYPE_ANY) {
drivers/cpufreq/acpi-cpufreq.c:         policy->shared_type =
CPUFREQ_SHARED_TYPE_ALL;
drivers/cpufreq/acpi-cpufreq.c:         policy->shared_type =
CPUFREQ_SHARED_TYPE_HW;
drivers/cpufreq/cpufreq-cpu0.c: policy->shared_type =
CPUFREQ_SHARED_TYPE_ANY; drivers/cpufreq/db8500-cpufreq.c:      
policy->shared_type =
CPUFREQ_SHARED_TYPE_ALL;
drivers/cpufreq/omap-cpufreq.c:         policy->shared_type =
CPUFREQ_SHARED_TYPE_ANY;
drivers/cpufreq/speedstep-centrino.c:           if
(policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
drivers/cpufreq/speedstep-centrino.c:           if
(policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)

I couldn't see any core file using this stuff other than acpi-cpufreq.c,
which is for x86 only systems if i am not wrong.

@Rafael: You view on this.. ? Actually i believe it was just used by
many ARM drivers without knowing the real use of it and new drivers
have just followed it.

I can get a patch to fix it at all places if you agree.

BTW, grep in full kernel source gave, which is again acpi only:

viresh at blr-linut-001:$ git grep shared_type

arch/arm/mach-tegra/cpu-tegra.c:        policy->shared_type =
CPUFREQ_SHARED_TYPE_ALL;
drivers/acpi/processor_perflib.c:
pr->performance->shared_type = CPUFREQ_SHARED_TYPE_ALL;
drivers/acpi/processor_perflib.c:
pr->performance->shared_type = CPUFREQ_SHARED_TYPE_HW;
drivers/acpi/processor_perflib.c:
pr->performance->shared_type = CPUFREQ_SHARED_TYPE_ANY;
drivers/acpi/processor_perflib.c:
match_pr->performance->shared_type =
drivers/acpi/processor_perflib.c:
 pr->performance->shared_type;
drivers/acpi/processor_perflib.c:
pr->performance->shared_type = CPUFREQ_SHARED_TYPE_ALL;
drivers/acpi/processor_throttling.c:
pthrottling->shared_type = DOMAIN_COORD_TYPE_SW_ALL;
drivers/acpi/processor_throttling.c:    pthrottling->shared_type =
pdomain->coord_type;
drivers/acpi/processor_throttling.c:
pthrottling->shared_type = DOMAIN_COORD_TYPE_SW_ALL;
drivers/acpi/processor_throttling.c:    if (p_throttling->shared_type
== DOMAIN_COORD_TYPE_SW_ANY) {
drivers/acpi/processor_throttling.c:
pthrottling->shared_type = DOMAIN_COORD_TYPE_SW_ALL;
drivers/cpufreq/acpi-cpufreq.c: if (policy->shared_type !=
CPUFREQ_SHARED_TYPE_ANY)
drivers/cpufreq/acpi-cpufreq.c: policy->shared_type = perf->shared_type;
drivers/cpufreq/acpi-cpufreq.c: if (policy->shared_type ==
CPUFREQ_SHARED_TYPE_ALL ||
drivers/cpufreq/acpi-cpufreq.c:     policy->shared_type ==
CPUFREQ_SHARED_TYPE_ANY) {
drivers/cpufreq/acpi-cpufreq.c:         policy->shared_type =
CPUFREQ_SHARED_TYPE_ALL;
drivers/cpufreq/acpi-cpufreq.c:         policy->shared_type =
CPUFREQ_SHARED_TYPE_HW;
drivers/cpufreq/cpufreq-cpu0.c: policy->shared_type =
CPUFREQ_SHARED_TYPE_ANY; drivers/cpufreq/db8500-cpufreq.c:      
policy->shared_type =
CPUFREQ_SHARED_TYPE_ALL;
drivers/cpufreq/omap-cpufreq.c:         policy->shared_type =
CPUFREQ_SHARED_TYPE_ANY;
drivers/cpufreq/speedstep-centrino.c:           if
(policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
drivers/cpufreq/speedstep-centrino.c:           if
(policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
drivers/net/wireless/rtlwifi/rtl8192ce/hw.c:
rtlpcipriv->bt_coexist.bt_radio_shared_type =
drivers/net/wireless/rtlwifi/rtl8723ae/hw.c:
pcipriv->bt_coexist.bt_radio_shared_type =
drivers/net/wireless/rtlwifi/rtl8723ae/hw.c:
pcipriv->bt_coexist.bt_radio_shared_type);
drivers/net/wireless/rtlwifi/wifi.h:    u8 bt_radio_shared_type;
drivers/xen/xen-acpi-processor.c:       dst->shared_type =
_pr->performance->shared_type;
drivers/xen/xen-acpi-processor.c:
dst->shared_type = CPUFREQ_SHARED_TYPE_ALL;
drivers/xen/xen-acpi-processor.c:
dst->shared_type = CPUFREQ_SHARED_TYPE_HW;
drivers/xen/xen-acpi-processor.c:
dst->shared_type = CPUFREQ_SHARED_TYPE_ANY;
include/acpi/processor.h:       unsigned int shared_type;
include/acpi/processor.h:       unsigned int shared_type;
include/linux/cpufreq.h:        unsigned int            shared_type;
/* ANY or ALL affected CPUs
include/xen/interface/platform.h:       uint32_t shared_type;     /*
coordination type of this processor */
tools/perf/util/dwarf-aux.c:             tag == DW_TAG_shared_type);

Well, the fact that it isn't used at the moment doesn't mean that it 
shouldn't be set correctly. The field is present in the structure and has 
a set of defined values - one of which should be selected. For example,
I can imagine some governor taking this information into account.

Best regards,
-- 
Tomasz Figa
Samsung Poland R&D Center
SW Solution Development, Linux Platform