From mboxrd@z Thu Jan 1 00:00:00 1970 From: a.kesavan@samsung.com (Abhilash Kesavan) Date: Fri, 11 Apr 2014 23:31:47 +0530 Subject: [PATCH 1/5] ARM: bL_switcher: Don't enable bL switcher on systems without CCI In-Reply-To: <1397239311-27717-1-git-send-email-a.kesavan@samsung.com> References: <1397239311-27717-1-git-send-email-a.kesavan@samsung.com> Message-ID: <1397239311-27717-2-git-send-email-a.kesavan@samsung.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Andrew Bresticker 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 Signed-off-by: Abhilash Kesavan --- 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 #include #include +#include #include #include @@ -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