[Skiboot] [RFC 12/12] npu2-opencapi: Log an warning when resetting a broken device

[Frederic Barrat]

On P9, the NPU doesn't support recovery if the link goes down
unexpectedly. It was not fully verified. We mark the device as broken
when we receive an error interrupt from the NPU. However, there's
nothing to prevent the OS from trying to reset the device; It may or
may not work, it's unsupported territory, so let's log a message to
make it clear, as it could help when debugging. We haven't hit any
cases where the reset goes badly enough that we'd want to prevent it,
so let it go for now. We can revisit later if we have evidence that
it's causing more problems than it is worth.

Signed-off-by: Frederic Barrat <fbarrat at linux.ibm.com>
---
 hw/npu2-opencapi.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/npu2-opencapi.c b/hw/npu2-opencapi.c
index dd238235..fc9155f1 100644
--- a/hw/npu2-opencapi.c
+++ b/hw/npu2-opencapi.c
@@ -1251,6 +1251,10 @@ static int64_t npu2_opencapi_freset(struct pci_slot *slot)
 			OCAPIINF(dev, "no card detected\n");
 			return OPAL_SUCCESS;
 		}
+		if (dev->flags & NPU2_DEV_BROKEN) {
+			OCAPIERR(dev, "Resetting a device which hit a previous error. Device recovery is not supported, so future behavior is undefined\n");
+			dev->flags &= ~NPU2_DEV_BROKEN;
+		}
 		slot->link_retries = OCAPI_LINK_TRAINING_RETRIES;
 		/* fall-through */
 	case OCAPI_SLOT_FRESET_INIT:
-- 
2.21.0