[PATCH] perf/arm-cmn: Decode CAL devices properly in debugfs

Robin Murphy robin.murphy at arm.com
Wed May 11 06:12:53 PDT 2022


The debugfs code is lazy, and since it only keeps the bottom byte of
each connect_info register to save space, it also treats the whole thing
as the device_type since the other bits were reserved anyway. Upon
closer inspection, though, this is no longer true on newer IP versions,
so let's be good and decode the exact field properly. This should help
it not get confused when a Component Aggregation Layer is present (which
is already implied if Node IDs are found for both device addresses
represented by the next two lines of the table).

Signed-off-by: Robin Murphy <robin.murphy at arm.com>
---
 drivers/perf/arm-cmn.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
index 282d2f874ec1..036f88f8508e 100644
--- a/drivers/perf/arm-cmn.c
+++ b/drivers/perf/arm-cmn.c
@@ -63,6 +63,7 @@
 #define CMN_MXP__CONNECT_INFO_P3	0x0030
 #define CMN_MXP__CONNECT_INFO_P4	0x0038
 #define CMN_MXP__CONNECT_INFO_P5	0x0040
+#define CMN__CONNECT_INFO_DEVICE_TYPE	GENMASK_ULL(4, 0)
 
 /* PMU registers occupy the 3rd 4KB page of each node's region */
 #define CMN_PMU_OFFSET			0x2000
@@ -400,7 +401,7 @@ static struct dentry *arm_cmn_debugfs;
 #ifdef CONFIG_DEBUG_FS
 static const char *arm_cmn_device_type(u8 type)
 {
-	switch(type) {
+	switch(FIELD_GET(CMN__CONNECT_INFO_DEVICE_TYPE, type)) {
 		case 0x00: return "        |";
 		case 0x01: return "  RN-I  |";
 		case 0x02: return "  RN-D  |";
-- 
2.35.3.dirty




More information about the linux-arm-kernel mailing list