From: Andrew Bresticker <abrestic@xxxxxxxxxxxx>
Do not enable the big.LITTLE switcher on systems that do not have an
ARM CCI (cache-coherent interconnect) present. Since the CCI is used
to maintain cache coherency between multiple clusters and peripherals,
it is unlikely that a system without CCI would support big.LITTLE.
Signed-off-by: Andrew Bresticker <abrestic@xxxxxxxxxxxx>
Signed-off-by: Abhilash Kesavan <a.kesavan@xxxxxxxxxxx>
---
arch/arm/common/bL_switcher.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/arch/arm/common/bL_switcher.c b/arch/arm/common/bL_switcher.c
index 5774b6e..c4fec1f 100644
--- a/arch/arm/common/bL_switcher.c
+++ b/arch/arm/common/bL_switcher.c
@@ -33,6 +33,7 @@
#include <linux/sysfs.h>
#include <linux/irqchip/arm-gic.h>
#include <linux/moduleparam.h>
+#include <linux/of.h>
#include <asm/smp_plat.h>
#include <asm/cputype.h>
@@ -796,6 +797,17 @@ core_param(no_bL_switcher, no_bL_switcher, bool, 0644);
static int __init bL_switcher_init(void)
{
int ret;
+ struct device_node *dn;
+
+ /*
+ * We don't want to set up the bL switcher if the machine doesn't
+ * support bL, so use the presence of a CCI to indicate whether or
+ * not bL is supported on this device.
+ */
+ dn = of_find_compatible_node(NULL, NULL, "arm,cci-400");
+ if (!dn)
+ return 0;
+ of_node_put(dn);
if (MAX_NR_CLUSTERS != 2) {
pr_err("%s: only dual cluster systems are supported\n", __func__);
--
1.7.9.5
--
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