[PATCH v2 4/4] coresight: etm4x: Fix access to resource selector registers

[Suzuki K Poulose]

Resource selector pair 0 is always implemented and reserved. We must not
touch it, even during save/restore for CPU Idle. Rest of the driver is
well behaved. Fix the offending ones.

Reported-by: Yabin Cui <yabinc at google.com>
Fixes: f188b5e76aae ("coresight: etm4x: Save/restore state across CPU low power states")
Signed-off-by: Suzuki K Poulose <suzuki.poulose at arm.com>
---
 drivers/hwtracing/coresight/coresight-etm4x-core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index b4b84f2317cd..577cf485e761 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -1758,7 +1758,8 @@ static int __etm4_cpu_save(struct etmv4_drvdata *drvdata)
 		state->trccntvr[i] = etm4x_read32(csa, TRCCNTVRn(i));
 	}
 
-	for (i = 0; i < drvdata->nr_resource * 2; i++)
+	/* Resource selector pair 0 is reserved */
+	for (i = 2; i < drvdata->nr_resource * 2; i++)
 		state->trcrsctlr[i] = etm4x_read32(csa, TRCRSCTLRn(i));
 
 	for (i = 0; i < drvdata->nr_ss_cmp; i++) {
@@ -1889,7 +1890,8 @@ static void __etm4_cpu_restore(struct etmv4_drvdata *drvdata)
 		etm4x_relaxed_write32(csa, state->trccntvr[i], TRCCNTVRn(i));
 	}
 
-	for (i = 0; i < drvdata->nr_resource * 2; i++)
+	/* Resource selector pair 0 is reserved */
+	for (i = 2; i < drvdata->nr_resource * 2; i++)
 		etm4x_relaxed_write32(csa, state->trcrsctlr[i], TRCRSCTLRn(i));
 
 	for (i = 0; i < drvdata->nr_ss_cmp; i++) {
-- 
2.34.1