[PATCH] ARM: mm: show prefetch state when either data or instr prefect is enabled

Russell King - ARM Linux linux at arm.linux.org.uk
Thu Jun 11 05:10:52 PDT 2015

On Thu, Jun 11, 2015 at 01:52:11PM +0200, Thomas Petazzoni wrote:
> The l2c310_enable() function shows the state of prefetch configuration
> only when both data *and* instruction prefetching is enabled, but the

Completely wrong, sorry.

> diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
> index d6e43d8..6bdf3a5 100644
> --- a/arch/arm/mm/cache-l2x0.c
> +++ b/arch/arm/mm/cache-l2x0.c
> @@ -656,7 +656,8 @@ static void __init l2c310_enable(void __iomem *base, u32 aux, unsigned num_lock)
>  	/* Read back resulting AUX_CTRL value as it could have been altered. */
>  	aux = readl_relaxed(base + L2X0_AUX_CTRL);

What this says is...
	first, bitwise _OR_ L310_AUX_CTRL_DATA_PREFETCH with
	L310_AUX_CTRL_INSTR_PREFETCH.  This produces a number which has
	_two_ bits set.

	then, bitwise _AND_ that number with the auxiliary control register.

	If the result is non-zero, then execute the code within the if() { }

So, I'm not going to take this patch.  The code is correct as it stands.

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