linux-kernel - Re: [PATCH v4] ARM: cache-l2x0.c: save aux ctrl for resume in case l2x0 is enabled before init

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Date:	Wed, 2 May 2012 09:17:45 +0800
From:	Yilu Mao <ylmao@...vell.com>
To:	Catalin Marinas <catalin.marinas@....com>
CC:	Lu Mao <ylmao@...vell.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux@....linux.org.uk" <linux@....linux.org.uk>,
	"Baohua.Song@....com" <Baohua.Song@....com>,
	"santosh.shilimkar@...com" <santosh.shilimkar@...com>,
	"robherring2@...il.com" <robherring2@...il.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v4] ARM: cache-l2x0.c: save aux ctrl for resume in case
 l2x0 is enabled before init

On 04/30/2012 09:34 PM, Catalin Marinas wrote:
> On 30 April 2012 14:16, Yilu Mao<ylmao@...vell.com>  wrote:
>> If l2x0 controller has been enabled when calling l2x0_init, the aux ctrl
>> register will not be saved in l2x0_saved_regs. Therefore we can not use
>> l2x0_saved_regs.aux_ctrl for resume later. This patch fixed the problem
>> by saving aux ctrl in l2x0_saved_regs just after it's being read from
>> the register.
>> And in case some bits of aux ctrl register are reserved, re-read and
>> save it properly after set it if l2x0 is disabled before init.
>>
>> Change-Id: I54f3002274ffe9cdc667dba81e36e08f2e121467
>> Signed-off-by: Yilu Mao<ylmao@...vell.com>
>> ---
>>   arch/arm/mm/cache-l2x0.c |    9 +++++++++
>>   1 files changed, 9 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
>> index a53fd2a..9893e58 100644
>> --- a/arch/arm/mm/cache-l2x0.c
>> +++ b/arch/arm/mm/cache-l2x0.c
>> @@ -320,6 +320,13 @@ void __init l2x0_init(void __iomem *base, u32 aux_val, u32 aux_mask)
>>         cache_id = readl_relaxed(l2x0_base + L2X0_CACHE_ID);
>>         aux = readl_relaxed(l2x0_base + L2X0_AUX_CTRL);
>>
>> +       /*
>> +        * In case l2x controller is enabled, the aux ctrl register
>> +        * can't be set. So the original value should be stored in
>> +        * the l2x0_saved_regs for restoring when resume.
>> +        */
>> +       l2x0_saved_regs.aux_ctrl = aux;
>
> Why not move this
>
>> +
>>         aux&= aux_mask;
>>         aux |= aux_val;
>>
>> @@ -364,6 +371,8 @@ void __init l2x0_init(void __iomem *base, u32 aux_val, u32 aux_mask)
>>                 /* l2x0 controller is disabled */
>>                 writel_relaxed(aux, l2x0_base + L2X0_AUX_CTRL);
>>
>> +               /* Re-read it in case some bits are reserved. */
>> +               aux = readl_relaxed(l2x0_base + L2X0_AUX_CTRL);
>
> and this
>
>>                 l2x0_saved_regs.aux_ctrl = aux;
>>
>>                 l2x0_inv_all();
>
> somewhere after the if block and we only read the aux once. The
> comment may no longer make sense though.
>
Hi Catalin,

I want to make it clear before I provide a new patch. :)
We can't only read once because we must read it before handle the 
aux_val and aux_mask arguments.
Do you still want the "l2x0_saved_regs.aux_ctrl = aux;" operation only 
located after the "if"?
If so, I will provide a patch for it.

-- 
Thanks.

Best Wishes,
Yilu Mao
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