[PATCH v6 24/30] powerpc/powernv/pci: Suppress an EEH error when reading an empty slot

[Sergey Miroshnichenko <s.miroshnichenko@yadro.com>]

Reading an empty slot returns all ones, which triggers a false EEH
error event on PowerNV. A rescan is performed after all the PEs have
been unmapped, so the reserved PE index is used for unfreezing.

CC: Oliver O'Halloran <oohall@gmail.com>
CC: Sam Bobroff <sbobroff@linux.ibm.com>
Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko@yadro.com>
---
 arch/powerpc/platforms/powernv/pci.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
index ffd546cf9204..e1b45dc96474 100644
--- a/arch/powerpc/platforms/powernv/pci.c
+++ b/arch/powerpc/platforms/powernv/pci.c
@@ -768,9 +768,16 @@ static int pnv_pci_read_config(struct pci_bus *bus,
 
 	*val = 0xFFFFFFFF;
 	pdn = pci_get_pdn_by_devfn(bus, devfn);
-	if (!pdn)
-		return pnv_pci_cfg_read_raw(phb->opal_id, bus->number, devfn,
-					    where, size, val);
+	if (!pdn) {
+		ret = pnv_pci_cfg_read_raw(phb->opal_id, bus->number, devfn,
+					   where, size, val);
+
+		if (!ret && (*val == EEH_IO_ERROR_VALUE(size)) && phb->unfreeze_pe)
+			phb->unfreeze_pe(phb, phb->ioda.reserved_pe_idx,
+					 OPAL_EEH_ACTION_CLEAR_FREEZE_ALL);
+
+		return ret;
+	}
 
 	if (!pnv_pci_cfg_check(pdn))
 		return PCIBIOS_DEVICE_NOT_FOUND;
-- 
2.23.0