Re: [PATCH v2] ARM: l2c: Add support for the "arm, shared-override" property

[Russell King - ARM Linux <linux@arm.linux.org.uk>]

On Thu, May 07, 2015 at 05:02:57PM +0100, Catalin Marinas wrote:
> On Thu, May 07, 2015 at 11:27:11AM +0200, Geert Uytterhoeven wrote:
> > diff --git a/Documentation/devicetree/bindings/arm/l2cc.txt b/Documentation/devicetree/bindings/arm/l2cc.txt
> > index 0dbabe9a6b0abb91..2484aed78c86546d 100644
> > --- a/Documentation/devicetree/bindings/arm/l2cc.txt
> > +++ b/Documentation/devicetree/bindings/arm/l2cc.txt
> > @@ -67,6 +67,12 @@ Optional properties:
> >    disable if zero.
> >  - arm,prefetch-offset : Override prefetch offset value. Valid values are
> >    0-7, 15, 23, and 31.
> > +- arm,shared-override : The default behavior of the pl310 cache controller with
> > +  respect to the shareable attribute is to transform "normal memory
> > +  non-cacheable transactions" into "cacheable no allocate" (for reads) or
> > +  "write through no write allocate" (for writes).
> > +  On systems where this may cause DMA buffer corruption, this property must be
> > +  specified to indicate that such transforms are precluded.
> >  
> >  Example:
> >  
> > diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
> > index e309c8f35af5af61..86d0e7461e5b0b18 100644
> > --- a/arch/arm/mm/cache-l2x0.c
> > +++ b/arch/arm/mm/cache-l2x0.c
> > @@ -1149,6 +1149,11 @@ static void __init l2c310_of_parse(const struct device_node *np,
> >  		}
> >  	}
> >  
> > +	if (of_property_read_bool(np, "arm,shared-override")) {
> > +		*aux_val |= L2C_AUX_CTRL_SHARED_OVERRIDE;
> > +		*aux_mask &= ~L2C_AUX_CTRL_SHARED_OVERRIDE;
> > +	}
> > +
> >  	prefetch = l2x0_saved_regs.prefetch_ctrl;
> >  
> >  	ret = of_property_read_u32(np, "arm,double-linefill", &val);
> 
> It looks fine to me.
> 
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> 
> (even better if a subsequent patch adds this property to all the dts
> files containing "arm,pl310" ;))

Even better would be for the boot loader/firmware to set the bit.

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