linux-kernel - Re: [PATCH 1/3] ARM: cache-l2c: Add flag to skip cache unlocking

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Message-ID: <1431407618.2411.86.camel@collabora.co.uk>
Date:	Tue, 12 May 2015 07:13:38 +0200
From:	Sjoerd Simons <sjoerd.simons@...labora.co.uk>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	Rob Herring <robh@...nel.org>, Tony Lindgren <tony@...mide.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
Subject: Re: [PATCH 1/3] ARM: cache-l2c: Add flag to skip cache unlocking

On Mon, 2015-05-11 at 23:29 +0100, Russell King - ARM Linux wrote:
> On Tue, May 12, 2015 at 12:17:29AM +0200, Sjoerd Simons wrote:
> >  extern struct outer_cache_fns outer_cache;
> > diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
> > index e309c8f..fff7888 100644
> > --- a/arch/arm/mm/cache-l2x0.c
> > +++ b/arch/arm/mm/cache-l2x0.c
> > @@ -136,7 +136,8 @@ static void l2c_enable(void __iomem *base, u32 aux, unsigned num_lock)
> >  	l2x0_saved_regs.aux_ctrl = aux;
> >  	l2c_configure(base);
> >  
> > -	l2c_unlock(base, num_lock);
> > +	if (!outer_cache.skip_unlock)
> > +		l2c_unlock(base, num_lock);
> 
> I think we can do better here.  If the non-secure lockdown access bit has
> been set, then proceed with the unlock:
> 
> 	if (readl_relaxed(base + L2X0_AUX_CTRL) & L310_AUX_CTRL_NS_LOCKDOWN)
> 		l2c_unlock(base, num_lock);
> 
> I don't see any need to add a flag for this.  This also eliminates your
> second patch.

Main reason I added the flag like this was to simplify the changes as
l2c_enable has no real knowledge about which type of cache it's running
on. 

But sure i will have a look at re-jigging the code such that the
situation is automatically detected rather then requiring the machine
specific code to flag it explicitely 

-- 
Sjoerd Simons <sjoerd.simons@...labora.co.uk>
Collabora Ltd.
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