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

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Message-ID: <20120424082810.GA9367@arm.com>
Date:	Tue, 24 Apr 2012 09:28:10 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Yilu Mao <ylmao@...vell.com>
Cc:	"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] ARM: cache-l2x0.c: save aux ctrl for resume in case
 that l2x0 is enabled before init

On Tue, Apr 24, 2012 at 03:41:20AM +0100, Yilu Mao 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.
> 
> Signed-off-by: Yilu Mao <ylmao@...vell.com>
> ---
>  arch/arm/mm/cache-l2x0.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
> index a53fd2a..3034b06 100644
> --- a/arch/arm/mm/cache-l2x0.c
> +++ b/arch/arm/mm/cache-l2x0.c
> @@ -320,6 +320,12 @@ 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.
> +	 */

Even better like this ;)

+	/*
+	 * 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;
> +
>  	aux &= aux_mask;
>  	aux |= aux_val;

I think that's the wrong place to save it, it should be after the
masking was done.

Anyway, if we cannot write this register in l2x0_init() because the L2
was enabled, do we expect the L2 to be disabled during resume?

-- 
Catalin
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