[PATCH v3] ARM: l2c: add options to overwrite prefetching behavior

On Fri, May 29, 2015 at 07:33:33PM +0200, Hauke Mehrtens wrote:

Will this make it into kernel 4.2 or do I have to do something so that
this will make it into 4.2?

I don't see anything wrong with it, but as ever, it needs to end up in the
patch system if it's not going to get buried beneath a huge pile of email.

Thanks.

Hauke

On 05/15/2015 11:52 PM, Hauke Mehrtens wrote:

quoted

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>
---
v2: only set prefetch
v1: set prefetch and aux

 Documentation/devicetree/bindings/arm/l2cc.txt |  4 ++++
 arch/arm/mm/cache-l2x0.c                       | 20 ++++++++++++++++++++
 2 files changed, 24 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..1aa970a 100644
--- a/arch/arm/mm/cache-l2x0.c
+++ b/arch/arm/mm/cache-l2x0.c

@@ -1199,6 +1199,26 @@ static void __init l2c310_of_parse(const struct device_node *np,
 		pr_err("L2C-310 OF arm,prefetch-offset property value is missing\n");
 	}
 
+	ret = of_property_read_u32(np, "arm,prefetch-data", &val);
+	if (ret == 0) {
+		if (val)
+			prefetch |= L310_PREFETCH_CTRL_DATA_PREFETCH;
+		else
+			prefetch &= ~L310_PREFETCH_CTRL_DATA_PREFETCH;
+	} else if (ret != -EINVAL) {
+		pr_err("L2C-310 OF arm,prefetch-data property value is missing\n");
+	}
+
+	ret = of_property_read_u32(np, "arm,prefetch-instr", &val);
+	if (ret == 0) {
+		if (val)
+			prefetch |= L310_PREFETCH_CTRL_INSTR_PREFETCH;
+		else
+			prefetch &= ~L310_PREFETCH_CTRL_INSTR_PREFETCH;
+	} else if (ret != -EINVAL) {
+		pr_err("L2C-310 OF arm,prefetch-instr property value is missing\n");
+	}
+
 	l2x0_saved_regs.prefetch_ctrl = prefetch;
 }
 

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