[RFC 3/3] powerpc/powernv: reset any PHBs in CAPI mode during initialisation

[Andrew Donnellan]

If we kexec into a new kernel on a machine where a PHB has been switched
into CAPI mode, we need to disable CAPI mode in the new kernel before
traffic begins to flow on the PHB and causes a machine checkstop.

During PHB initialisation, ask OPAL whether each PHB is in CAPI mode, and
if so, do a complete reset in order to disable CAPI mode.

This requires a version of skiboot that implements the
OPAL_PCI_GET_PHB_CAPI_MODE call (introduced at the same time that the
capability to disable CAPI mode during complete resets was introduced).

Signed-off-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>

---

Corresponding skiboot code: http://patchwork.ozlabs.org/patch/670782/
---
 arch/powerpc/platforms/powernv/pci-ioda.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index ca5e9b5..bd76651 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -3526,6 +3526,7 @@ static void __init pnv_pci_init_ioda_phb(struct device_node *np,
 	const __be32 *prop32;
 	int len;
 	unsigned int segno;
+	bool capi_mode = false;
 	u64 phb_id;
 	void *aux;
 	long rc;
@@ -3741,8 +3742,17 @@ static void __init pnv_pci_init_ioda_phb(struct device_node *np,
 	 * shutdown PCI devices correctly. We already got IODA table
 	 * cleaned out. So we have to issue PHB reset to stop all PCI
 	 * transactions from previous kernel.
+	 *
+	 * Additionally, if the PHB is in CAPI mode, we also need to
+	 * reset it to get it out of CAPI mode.
 	 */
-	if (is_kdump_kernel()) {
+	if (opal_check_token(OPAL_PCI_GET_PHB_CAPI_MODE) &&
+	    opal_pci_get_phb_capi_mode(phb_id) == OPAL_PHB_CAPI_MODE_CAPI) {
+		pr_info("  PHB in CAPI mode, reset required\n");
+		capi_mode = true;
+	}
+
+	if (is_kdump_kernel() || capi_mode) {
 		pr_info("  Issue PHB reset ...\n");
 		pnv_eeh_phb_reset(hose, EEH_RESET_FUNDAMENTAL);
 		pnv_eeh_phb_reset(hose, EEH_RESET_DEACTIVATE);
-- 
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