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

[Stewart Smith]

Andrew Donnellan <andrew.donnellan at au1.ibm.com> writes:
> 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.

Okay - I'll hold off merging until I see a Tested-by.

> This is based off 5.1.18. The code in question has been
> rewritten in 5.3.

Okay, when merge time comes, I'll pull it into 5.1.x only.

-- 
Stewart Smith
OPAL Architect, IBM.