[PATCH] ARM: l2c: add options to overwrite prefetching behavior

[PATCH] ARM: l2c: add options to overwrite prefetching behavior

[Hauke Mehrtens]

These options make it possible to overwrites the data and instruction
prefetching behavior of the arm pl310 cache controller.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
---
 Documentation/devicetree/bindings/arm/l2cc.txt |  4 ++++
 arch/arm/mm/cache-l2x0.c                       | 10 ++++++++++
 2 files changed, 14 insertions(+)

diff --git a/Documentation/devicetree/bindings/arm/l2cc.txt b/Documentation/devicetree/bindings/arm/l2cc.txt
index 0dbabe9..528821a 100644
--- a/Documentation/devicetree/bindings/arm/l2cc.txt
+++ b/Documentation/devicetree/bindings/arm/l2cc.txt
@@ -67,6 +67,10 @@ Optional properties:
   disable if zero.
 - arm,prefetch-offset : Override prefetch offset value. Valid values are
   0-7, 15, 23, and 31.
+- arm,prefetch-data : Enable data prefetch. Enabling prefetching
+  can improve performance.
+- arm,prefetch-instr : Enable instruction prefetch. Enabling prefetching
+  can improve performance.
 
 Example:
 
diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
index e309c8f..f919548 100644
--- a/arch/arm/mm/cache-l2x0.c
+++ b/arch/arm/mm/cache-l2x0.c
@@ -1149,6 +1149,16 @@ static void __init l2c310_of_parse(const struct device_node *np,
 		}
 	}
 
+	if (of_property_read_bool(np, "arm,prefetch-data")) {
+		*aux_val |= L310_AUX_CTRL_DATA_PREFETCH;
+		*aux_mask &= ~L310_AUX_CTRL_DATA_PREFETCH;
+	}
+
+	if (of_property_read_bool(np, "arm,prefetch-instr")) {
+		*aux_val |= L310_AUX_CTRL_INSTR_PREFETCH;
+		*aux_mask &= ~L310_AUX_CTRL_INSTR_PREFETCH;
+	}
+
 	prefetch = l2x0_saved_regs.prefetch_ctrl;
 
 	ret = of_property_read_u32(np, "arm,double-linefill", &val);
-- 
2.1.4

Re: [PATCH] ARM: l2c: add options to overwrite prefetching behavior

[Russell King - ARM Linux]

On Thu, May 14, 2015 at 01:42:00AM +0200, Hauke Mehrtens wrote:
> diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
> index e309c8f..f919548 100644
> --- a/arch/arm/mm/cache-l2x0.c
> +++ b/arch/arm/mm/cache-l2x0.c
> @@ -1149,6 +1149,16 @@ static void __init l2c310_of_parse(const struct device_node *np,
>  		}
>  	}
>  
> +	if (of_property_read_bool(np, "arm,prefetch-data")) {
> +		*aux_val |= L310_AUX_CTRL_DATA_PREFETCH;
> +		*aux_mask &= ~L310_AUX_CTRL_DATA_PREFETCH;
> +	}
> +
> +	if (of_property_read_bool(np, "arm,prefetch-instr")) {
> +		*aux_val |= L310_AUX_CTRL_INSTR_PREFETCH;
> +		*aux_mask &= ~L310_AUX_CTRL_INSTR_PREFETCH;
> +	}
> +
>  	prefetch = l2x0_saved_regs.prefetch_ctrl;
>  
>  	ret = of_property_read_u32(np, "arm,double-linefill", &val);

Please move these down along-side the "arm,prefetch-offset" property
parsing, and please update the prefetch value using
L310_PREFETCH_CTRL_DATA_PREFETCH and L310_PREFETCH_CTRL_INSTR_PREFETCH
instead.

These are in fact the same bit, but let's try to keep the prefetch
configuration all in one place and via the same method.

-- 
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html