From: Sudeep.KarkadaNagesha@arm•com (Sudeep KarkadaNagesha)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 4/4] drivers: clocksource: add CPU PM notifier for ARM architected timer
Date: Tue, 02 Jul 2013 18:24:31 +0100 [thread overview]
Message-ID: <51D30CCF.5020808@arm.com> (raw)
In-Reply-To: <1372781381.3689.27.camel@linaro1.home>
On 02/07/13 17:09, Jon Medhurst (Tixy) wrote:
> On Tue, 2013-06-18 at 18:07 +0100, Sudeep KarkadaNagesha wrote:
>> From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm•com>
>>
>> Few control settings done in architected timer as part of initialisation
>> are lost when CPU enters deeper power states. They need to be re-initialised
>> when the CPU is (warm)reset again.
>>
>> This patch moves all such initialisation into separate function that can
>> be used both in cold and warm CPU reset paths. It also adds CPU PM
>> notifiers to do the timer initialisation on warm resets.
>>
>> Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm•com>
>> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm•com>
>> Reviewed-by: Will Deacon <will.deacon@arm•com>
>> ---
>> drivers/clocksource/arm_arch_timer.c | 51 +++++++++++++++++++++++++++++++-----
>> 1 file changed, 44 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
>> index 11aaf06..1c691b1 100644
>> --- a/drivers/clocksource/arm_arch_timer.c
>> +++ b/drivers/clocksource/arm_arch_timer.c
>> @@ -13,6 +13,7 @@
>> #include <linux/device.h>
>> #include <linux/smp.h>
>> #include <linux/cpu.h>
>> +#include <linux/cpu_pm.h>
>> #include <linux/clockchips.h>
>> #include <linux/interrupt.h>
>> #include <linux/of_irq.h>
>> @@ -123,10 +124,20 @@ static int arch_timer_set_next_event_phys(unsigned long evt,
>> return 0;
>> }
>>
>> -static int __cpuinit arch_timer_setup(struct clock_event_device *clk)
>> +static void arch_timer_initialise(void)
>> {
>> int evt_stream_div, pos;
>>
>> + /* Find the closest power of two to the divisor */
>> + evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ;
>> + pos = fls(evt_stream_div);
>> + if (pos > 1 && !(evt_stream_div & (1 << (pos - 2))))
>> + pos--;
>> + arch_counter_set_user_access(min(pos, 15));
>
> Would it not be good to calculate the value once in arch_timer_setup
> rather than repeatedly in this function? The calculations aren't that
> expensive, but when I gave these patches a spin on TC2 I noticed that
> this function gets called >500 times a second, so it seems a bit
> wasteful.
>
Makes sense, will save the divider and re-use it.
Regards,
Sudeep
next prev parent reply other threads:[~2013-07-02 17:24 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-18 17:06 [PATCH 0/4] ARM/ARM64 architected timer updates Sudeep KarkadaNagesha
2013-06-18 17:07 ` [PATCH 1/4] drivers: clocksource: configure event stream for ARM arch timer Sudeep KarkadaNagesha
2013-06-18 17:07 ` [PATCH 2/4] ARM: arch_timer: add macros for bits in control register Sudeep KarkadaNagesha
2013-06-18 17:07 ` [PATCH 3/4] ARM/ARM64: arch_timer: remove __cpuinit attribute for arch_counter_set_user_access Sudeep KarkadaNagesha
2013-06-18 17:58 ` Sudeep KarkadaNagesha
2013-06-18 17:07 ` [PATCH 4/4] drivers: clocksource: add CPU PM notifier for ARM architected timer Sudeep KarkadaNagesha
2013-07-02 16:09 ` Jon Medhurst (Tixy)
2013-07-02 17:24 ` Sudeep KarkadaNagesha [this message]
2013-07-22 11:21 ` [PATCH v2 0/3] ARM/ARM64 architected timer updates Sudeep KarkadaNagesha
2013-07-22 11:21 ` [PATCH v2 1/3] drivers: clocksource: configure event stream for ARM arch timer Sudeep KarkadaNagesha
2013-07-23 10:23 ` Catalin Marinas
2013-07-23 10:33 ` Will Deacon
2013-07-23 11:12 ` Catalin Marinas
2013-07-25 9:45 ` [PATCH v3 " Sudeep KarkadaNagesha
2013-08-12 13:32 ` Sudeep KarkadaNagesha
2013-07-22 11:21 ` [PATCH v2 2/3] ARM: arch_timer: add macros for bits in control register Sudeep KarkadaNagesha
2013-07-22 11:21 ` [PATCH v2 3/3] drivers: clocksource: add CPU PM notifier for ARM architected timer Sudeep KarkadaNagesha
2013-08-02 9:32 ` [PATCH v2 0/3] ARM/ARM64 architected timer updates Sudeep KarkadaNagesha
2013-08-02 9:48 ` Daniel Lezcano
2013-08-02 9:55 ` Sudeep KarkadaNagesha
2013-08-02 12:12 ` Daniel Lezcano
2013-08-05 16:25 ` Sudeep KarkadaNagesha
2013-08-06 8:09 ` Daniel Lezcano
2013-08-06 9:01 ` Sudeep KarkadaNagesha
2013-08-12 13:16 ` Daniel Lezcano
2013-08-13 17:29 ` [PATCH v3 0/6] " Sudeep KarkadaNagesha
2013-08-13 17:29 ` [PATCH v3 1/6] ARM/ARM64: arch_timer: add macros for bits in control register Sudeep KarkadaNagesha
2013-08-14 8:50 ` Daniel Lezcano
2013-08-14 9:03 ` Marc Zyngier
2013-08-14 9:23 ` Daniel Lezcano
2013-08-13 17:29 ` [PATCH v3 2/6] drivers: clocksource: configure event stream for ARM arch timer Sudeep KarkadaNagesha
2013-08-13 17:29 ` [PATCH v3 3/6] ARM: arch_timer: configure and enable event stream Sudeep KarkadaNagesha
2013-08-13 17:29 ` [PATCH v3 4/6] ARM64: " Sudeep KarkadaNagesha
2013-08-20 13:27 ` Will Deacon
2013-08-20 14:27 ` Sudeep KarkadaNagesha
2013-08-20 16:16 ` Will Deacon
2013-08-20 16:23 ` Sudeep KarkadaNagesha
2013-08-20 17:08 ` Sudeep KarkadaNagesha
2013-08-21 17:52 ` Will Deacon
2013-08-13 17:29 ` [PATCH v3 5/6] drivers: clocksource: enable hwcaps for event stream on ARM arch timer Sudeep KarkadaNagesha
2013-08-13 17:29 ` [PATCH v3 6/6] drivers: clocksource: add CPU PM notifier for ARM architected timer Sudeep KarkadaNagesha
2013-08-14 9:08 ` [PATCH v3 0/6] ARM/ARM64 architected timer updates Daniel Lezcano
2013-08-14 9:17 ` Sudeep KarkadaNagesha
2013-08-14 10:51 ` Daniel Lezcano
2013-08-14 11:03 ` Sudeep KarkadaNagesha
2013-08-14 15:00 ` Daniel Lezcano
2013-08-20 17:14 ` Sudeep KarkadaNagesha
2013-08-23 9:26 ` Catalin Marinas
2013-08-23 9:57 ` Sudeep KarkadaNagesha
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