Re: [PATCH v2 3/3] ARM: OMAP2+: AM43x: L2 cache support

[Santosh Shilimkar <santosh.shilimkar@ti.com>]

On Tuesday 08 April 2014 10:53 AM, Sekhar Nori wrote:
> On Friday 04 April 2014 03:48 PM, Russell King - ARM Linux wrote:
>> On Fri, Apr 04, 2014 at 03:40:29PM +0530, Sekhar Nori wrote:
>>> diff --git a/arch/arm/mach-omap2/omap4-common.c b/arch/arm/mach-omap2/omap4-common.c
>>> index f8b8dac..6b2a056 100644
>>> --- a/arch/arm/mach-omap2/omap4-common.c
>>> +++ b/arch/arm/mach-omap2/omap4-common.c
>>> @@ -224,6 +224,14 @@ int __init omap4_l2_cache_init(void)
>>>  
>>>  	return omap_l2_cache_init(aux_ctrl, 0xc19fffff);
>>>  }
>>> +
>>> +int __init am43xx_l2_cache_init(void)
>>> +{
>>> +	u32 aux_ctrl = L310_AUX_CTRL_DATA_PREFETCH |
>>> +		       L310_AUX_CTRL_INSTR_PREFETCH;
>>
>> It would be good to documenting the difference between this and OMAP4,
>> and why you have chosen different values.
> 
> There are two main differences:
> 
> 1) OMAP4 sets Shared attribute override enable bit. TBH, I think this is
> not needed even in OMAP4 with latest kernel, but I am not sure if I can
> do this safely without breaking any usecase currently working with OMAP4.
> 
Wrong. Shared bit is mandatory for the OMAP4. Its a SMP system
which needs that.

> 2) OMAP4 sets NS lockdown and NS interrupt access control bits. I
> searched through the commit history of L2 cache support on OMAP4 but
> there is no mention of why this was needed on OMAP4. I am checking
> internally on the history behind this.
>
These have also come from the aligned settings with hardware folks.
 
> 3) OMAP4 sets cache replacement policy to RR which is not a big deal
> since thats the default anyway. We can probably drop this setting even
> from OMAP4.
> 
Don't change anything on OMAP4 since these settings have come up from
multiple alignments.

In my view, Aegis can use exact same setting as OMAP4. Things like
shared bit etc would not make much difference because of UP config,
keeping that doesn't hurt either.

Why don't you just re-use that as is ? Sorry if I have missed any
other discussion on the thread.

Regards,
Santosh