[Skiboot] [PATCH stable 5.1] hw/phb3: set PHB retry state correctly when fresetting during a creset

[Andrew Donnellan]

When we're doing a complete reset, after we complete the ETU reset and wait
for the PHB to return, we need to do a fundamental reset.

When we do the fundamental reset, we poll for a link up. This isn't always
successful on the first attempt. In phb3_sm_link_poll(), if we time out
while waiting for the link to come up, we call phb3_retry_state() to reset
p->state back to p->retry_state and poll again. On the second poll, we
clear the retry state so we don't retry again.

However, when we do the fundamental reset as part of a complete reset, we
don't explicitly set the retry state. This means that we only retry if
there wasn't an earlier fundamental reset that had to retry and thus
cleared the retry state. This reduces the reliability of the complete reset
process.

In phb3_sm_complete_reset(), when in state PHB3_STATE_CRESET_FRESET,
set the retry state to PHB3_STATE_FRESET_START, as is done in
phb3_fundamental_reset().

Reported-by: Pradipta Ghosh <pradghos at in.ibm.com>
Suggested-by: Gavin Shan <gwshan at linux.vnet.ibm.com>
Cc: Uma Krishnan <ukrishn at linux.vnet.ibm.com>
Cc: Matthew Ochs <mrochs at linux.vnet.ibm.com>
Signed-off-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>

---

Very lightly tested - I've asked Pradipta and Uma to test this
properly and ensure this gets rid of their problem.

This is based off 5.1.18. The code in question has been
rewritten in 5.3.
---
 hw/phb3.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/phb3.c b/hw/phb3.c
index 4c27309..62b67cb 100644
--- a/hw/phb3.c
+++ b/hw/phb3.c
@@ -2478,6 +2478,7 @@ static int64_t phb3_sm_complete_reset(struct phb3 *p)
 		return phb3_set_sm_timeout(p, msecs_to_tb(100));
 	case PHB3_STATE_CRESET_FRESET:
 		p->state = PHB3_STATE_FUNCTIONAL;
+		p->retry_state = PHB3_STATE_FRESET_START;
 		p->flags |= PHB3_CFG_BLOCKED;
 		return phb3_sm_fundamental_reset(p);
 	default:
-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan at au1.ibm.com  IBM Australia Limited