Subject: [PATCH V4] ARM: OMAP5/DRA7: realtime_counter: Configure CNTFRQ register

From: [email-masked] (Sricharan R)
Date: Wed, 9 Oct 2013 18:50:23 +0530

On Wednesday 09 October 2013 06:47 PM, Santosh Shilimkar wrote:
> On Wednesday 09 October 2013 09:15 AM, Sricharan R wrote:
>> Santosh,
>>
>> On Wednesday 09 October 2013 03:35 AM, Santosh Shilimkar wrote:
>>> On Tuesday 08 October 2013 05:45 PM, Tony Lindgren wrote:
>>>> * Sricharan R <[email-masked]> [131003 03:27]:
>>>>> On Wednesday 18 September 2013 09:32 PM, Sricharan R wrote:
>>>>>> --- a/arch/arm/boot/dts/omap5.dtsi
>>>>>> +++ b/arch/arm/boot/dts/omap5.dtsi
>>>>>> @@ -52,7 +52,6 @@
>>>>>>  			     <GIC_PPI 14 (GIC_CPU_MASK_RAW(3) | IRQ_TYPE_LEVEL_LOW)>,
>>>>>>  			     <GIC_PPI 11 (GIC_CPU_MASK_RAW(3) | IRQ_TYPE_LEVEL_LOW)>,
>>>>>>  			     <GIC_PPI 10 (GIC_CPU_MASK_RAW(3) | IRQ_TYPE_LEVEL_LOW)>;
>>>>>> -		clock-frequency = <6144000>;
>>>>>>  	};
>>>>>>  
>>>>>>  	gic: interrupt-controller at 48211000 {
>>>> Can the above be done later on in a separate clean-up patch?
>>>> If so I can drop that part as that removes a dependency to the
>>>> .dts patches queued by Benoit.
>>>>
>>> This can be applied separately. 
>>>
>>>  
>>>>>> --- a/arch/arm/mach-omap2/omap-smp.c
>>>>>> +++ b/arch/arm/mach-omap2/omap-smp.c
>>>>>> @@ -41,6 +41,8 @@
>>>>>>  
>>>>>>  u16 pm44xx_errata;
>>>>>>  
>>>>>> +extern unsigned long arch_timer_freq;
>>>>>> +
>>>>>>  /* SCU base address */
>>>>>>  static void __iomem *scu_base;
>>>>>>  
>>>> No externs in *.c files please, checkpatch.pl and sparse should warn
>>>> about this.
>>>>
>>>>>  Are you planning to pull this patch and the below $subject patch as well? They are
>>>>>  acked and tested.
>>>>>
>>>>>  ARM: DRA7: realtime_counter: Add ratio registers for 20MHZ sys-clk frequency
>>>>>
>>>>>   http://www.spinics.net/lists/linux-omap/msg97281.html
>>>> The 20MHz patch I've applied, just noticed the above things
>>>> when was about to apply this.
>>>>
>>> Now re-looking at the patch, I think this extern stuff can be and
>>> should be avoided. It needs order change though like below. Not
>>> tested but should work.
>>>
>>> diff --git a/arch/arm/mach-omap2/timer.c b/arch/arm/mach-omap2/timer.c
>>> index fa74a06..c8d8308 100644
>>> --- a/arch/arm/mach-omap2/timer.c
>>> +++ b/arch/arm/mach-omap2/timer.c
>>> @@ -631,10 +631,9 @@ void __init omap4_local_timer_init(void)
>>>  #ifdef CONFIG_SOC_OMAP5
>>>  void __init omap5_realtime_timer_init(void)
>>>  {
>>> -	omap4_sync32k_timer_init();
>>>  	realtime_counter_init();
>>> -
>>>  	clocksource_of_init();
>>> +	omap4_sync32k_timer_init();
>>>  }
>>>  #endif /* CONFIG_SOC_OMAP5 */
>>>  
>>> Then, the CNTFREQ programming needs to be moved to
>>> realtime_counter_init(). It should be actually part of that
>>> first place instead of timer_init().
>>>
>>> On secondary CPU then a simple asm accessor can
>>> read the CNTFREQ and pass that to SMC.
>> Sorry,  I did not quite get you here. You mean an asm accessor to
>>  the read the variable that is set in timer.c ?
>>
> Reading CNTFREQ CP15 directly....
>
  Sorry, Still not clear. CNTFREQ is per-cpu register. So when
 the secondary cpu init happens on CPU1, then you mean we will have
 to read it from CPU0 register and pass it for secondary ?

Regards,
 Sricharan