[PATCH] cpuidle: warn and fixup on sanity check instead of rejecting the driver

[Val Packett]

On Device Tree platforms, the latency and target residency values come
directly from device trees, which are numerous and weren't all written
with cpuidle invariants in mind. For example, qcom/hamoa.dtsi currently
trips this check: exit latency 680000 > residency 600000.

Instead of harshly rejecting the entire cpuidle driver with a mysterious
error message, print a warning and set the target residency value to be
equal to the exit latency.

Fixes: 76934e495cdc ("cpuidle: Add sanity check for exit latency and target residency")
Signed-off-by: Val Packett <val at packett.cool>
---
 drivers/cpuidle/driver.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
index 1c295a93d582..06aeb59c1017 100644
--- a/drivers/cpuidle/driver.c
+++ b/drivers/cpuidle/driver.c
@@ -199,8 +199,11 @@ static int __cpuidle_driver_init(struct cpuidle_driver *drv)
 		 * exceed its target residency which is assumed in cpuidle in
 		 * multiple places.
 		 */
-		if (s->exit_latency_ns > s->target_residency_ns)
-			return -EINVAL;
+		if (s->exit_latency_ns > s->target_residency_ns) {
+			pr_warn("cpuidle: state %d: exit latency %lld > residency %lld (fixing)\n",
+				i, s->exit_latency_ns, s->target_residency_ns);
+			s->target_residency_ns = s->exit_latency_ns;
+		}
 	}
 
 	return 0;
-- 
2.51.0