[PATCH 3/4] perf/arm_cspmu: Improve sub-module error reporting

[Robin Murphy <robin.murphy@arm.com>]

When waiting for a sub-module to register, we return a bare
-EPROBE_DEFER that ends up showing the end user:

  platform arm-cs-arch-pmu.1: deferred probe pending (no reason)

wherein it's not necessarily clear that they might need to take some
action to ensure the appropriate module is available to load. Let's use
dev_err_probe() here so we can show exactly what we're waiting for.

Similarly, in the case where something's gone horribly wrong with an
already-registered module, we can use dev_WARN() to standardise the
device/driver attribution rather than just open-coding "arm_cspmu".

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
 drivers/perf/arm_cspmu/arm_cspmu.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/perf/arm_cspmu/arm_cspmu.c b/drivers/perf/arm_cspmu/arm_cspmu.c
index 0570be74d11f..0b26a1588eba 100644
--- a/drivers/perf/arm_cspmu/arm_cspmu.c
+++ b/drivers/perf/arm_cspmu/arm_cspmu.c
@@ -438,13 +438,15 @@ static int arm_cspmu_init_impl_ops(struct arm_cspmu *cspmu)
 				if (ret)
 					module_put(match->module);
 			} else {
-				WARN(1, "arm_cspmu failed to get module: %s\n",
+				dev_WARN(cspmu->dev, "Failed to get module: %s\n",
 					match->module_name);
 				ret = -EINVAL;
 			}
 		} else {
 			request_module_nowait(match->module_name);
-			ret = -EPROBE_DEFER;
+			ret = dev_err_probe(cspmu->dev, -EPROBE_DEFER,
+					    "Waiting for module %s to load\n",
+					    match->module_name);
 		}
 
 		mutex_unlock(&arm_cspmu_lock);
-- 
2.54.0.dirty