pci: Fix presence detect on PHB3

The presence detect bit in the standard root complex config space is
not properly implemented on some IBM PHBs. Using it during probe is
incorrect.

We already have a workaround using the hotplug override "AB" detect
bits in the PHB3 code but it somewhat relies on the standard presence
detect bit returning false positives, which happened on Venice/Murano
but no longer happens in Naples.

Similarly, all the slot control stuff in the generic pci_enable_bridge()
isn't going to work properly on the PHB root complex and is unnecessary
as this code is only called after the upper layers have verified the
presence of a valid link on the PHB (the slot power control for the PHB
is handled separately).

This fixes it all by removing the AB detect flag, and unconditionally
using those bits in PHB3 presence detect along with making sure the
code in pci_enable_bridge() that manipulates the slot controls is
only executed on downstream ports.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

1 files changed, 0 insertions, 1 deletions

diff --git a/include/phb3.h b/include/phb3.h
index 3db57add..f7859164 100644
--- a/include/phb3.h
+++ b/include/phb3.h
@@ -292,7 +292,6 @@ struct phb3 {
 
 	bool			skip_perst; /* Skip first perst */
 	bool			has_link;
-	bool			use_ab_detect;
 	enum phb3_state		state;
 	uint64_t		delay_tgt_tb;
 	uint64_t		retries;