[PATCH v1 1/1] cxl/mem: Do not return error if CONFIG_CXL_MCE unset

[Li Ming]

CONFIG_CXL_MCE depends on CONFIG_MEMORY_FAILURE, if
CONFIG_CXL_MCE is not set, devm_cxl_register_mce_notifier() will return
an -EOPNOTSUPP, it will cause cxl_mem_state_create() failure , and then
cxl pci device probing failed. In this case, it should not break cxl pci
device probing.

Add a checking in cxl_mem_state_create() to check if the returned value
of devm_cxl_register_mce_notifier() is -EOPNOTSUPP, if yes, just output
a warning log, do not let cxl_mem_state_create() return an error.

Signed-off-by: Li Ming <ming.li@xxxxxxxxxxxx>
---
I hit this issue on my cxl_test environment with latest cxl-next. If
CONFIG_MEMORY_FAILURE is unset, all cxl pci devices will fail to probe.

...
[    6.337952] cxl_mock_mem cxl_mem.6: probe with driver cxl_mock_mem failed with error -95
[    6.338880] cxl_mock_mem cxl_mem.4: probe with driver cxl_mock_mem failed with error -95
[    6.339593] cxl_mock_mem cxl_mem.9: probe with driver cxl_mock_mem failed with error -95
[    6.340588] cxl_mock_mem cxl_mem.2: probe with driver cxl_mock_mem failed with error -95
[    6.340914] cxl_mock_mem cxl_mem.0: probe with driver cxl_mock_mem failed with error -95
[    6.345762] cxl_mock_mem cxl_rcd.10: probe with driver cxl_mock_mem failed with error -95
[    6.345793] cxl_mock_mem cxl_mem.7: probe with driver cxl_mock_mem failed with error -95
...
[    6.519824] cxl_pci 0000:c4:00.0: probe with driver cxl_pci failed with error -95
[    6.520178] cxl_pci 0000:38:00.0: probe with driver cxl_pci failed with error -95
...

base-commit: 22eea823f69ae39dc060c4027e8d1470803d2e49 cxl/next
---
 drivers/cxl/core/mbox.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index 13cac98846bc..d72764056ce6 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -1503,7 +1503,9 @@ struct cxl_memdev_state *cxl_memdev_state_create(struct device *dev)
 	mds->cxlds.type = CXL_DEVTYPE_CLASSMEM;
 
 	rc = devm_cxl_register_mce_notifier(dev, &mds->mce_notifier);
-	if (rc)
+	if (rc == -EOPNOTSUPP)
+		dev_warn(dev, "CXL MCE unsupported\n");
+	else if (rc)
 		return ERR_PTR(rc);
 
 	return mds;
-- 
2.34.1