Re: [PATCH] OMAP3: decrease cpufreq transition latency

[Mike Turquette <mturquette@ti.com>]

Kevin Hilman wrote:
> Mike Turquette <mturquette@gmail.com> writes:
> 
>> Adjust OMAP3 frequency transition latency from 10,000,000uS to a more
>> reasonable 300,000uS.  This causes ondemand and conservative governors to
>> sample CPU load more often resulting in more responsive behavior.
>>
>> Tested on Android 2.6.29; using this value and conservative governor, CORE
>> power consumption on Zoom2 was comparable to the old and unresponsive
>> 10,000,000uS value while UI responsiveness was greatly improved.
>>
>> This patch applies against Tony's omap-fixes branch.
>>
>> Signed-off-by: Mike Turquette <mturquette@ti.com>
>> ---
>>  arch/arm/plat-omap/cpu-omap.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/arm/plat-omap/cpu-omap.c b/arch/arm/plat-omap/cpu-omap.c
>> index 1868c0d..341235c 100644
>> --- a/arch/arm/plat-omap/cpu-omap.c
>> +++ b/arch/arm/plat-omap/cpu-omap.c
>> @@ -127,7 +127,7 @@ static int __init omap_cpu_init(struct cpufreq_policy *policy)
>>  	}
>>  
>>  	/* FIXME: what's the actual transition time? */
> 
> Can probably drop this 'FIXME' comment now.

I chose not to drop the FIXME since the worst-case transition time is 
still unknown.  At some point I'd like to revisit this number with 
something better supported by data from the hardware guys.  This number 
was deemed "safe", but may not be optimal.

Mike

>> -	policy->cpuinfo.transition_latency = 10 * 1000 * 1000;
>> +	policy->cpuinfo.transition_latency = 300 * 1000;
> 
> otherwise,
> 
> Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
> 
> Tony, can this still be queued for .32-rc?
> 
> Kevin
>