[v3] powerpc/powernv: Add ppc_pci_reset_phbs parameter to issue a PHB reset

Message ID 20171117185859.2756-1-gpiccoli@linux.vnet.ibm.com
State New
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  • [v3] powerpc/powernv: Add ppc_pci_reset_phbs parameter to issue a PHB reset
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Commit Message

Guilherme G. Piccoli Nov. 17, 2017, 6:58 p.m.
During a kdump kernel boot in PowerPC, we request a reset of the PHBs
to the FW. It makes sense, since if we are booting a kdump kernel it
means we had some trouble before and we cannot rely in the adapters'
health; they could be in a bad state, hence the reset is needed.

But this reset is useful not only in kdump - there are situations,
specially when debugging drivers, that we could break an adapter in
a way it requires such reset. One can tell to just go ahead and
reboot the machine, but happens that many times doing kexec is much
faster, and so preferable than a full power cycle.

This patch adds the ppc_pci_reset_phbs parameter to perform such reset.

Signed-off-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>

* v3: Changed parameter name, adding prefix "ppc_" [mpe suggestion]

 arch/powerpc/platforms/powernv/pci-ioda.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)


diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index fb5cd7511189..19f1b0021585 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -89,6 +89,7 @@  void pe_level_printk(const struct pnv_ioda_pe *pe, const char *level,
 static bool pnv_iommu_bypass_disabled __read_mostly;
+static bool pci_reset_phbs __read_mostly;
 static int __init iommu_setup(char *str)
@@ -110,6 +111,14 @@  static int __init iommu_setup(char *str)
 early_param("iommu", iommu_setup);
+static int __init pci_reset_phbs_setup(char *str)
+	pci_reset_phbs = true;
+	return 0;
+early_param("ppc_pci_reset_phbs", pci_reset_phbs_setup);
 static inline bool pnv_pci_is_m64(struct pnv_phb *phb, struct resource *r)
@@ -4014,9 +4023,10 @@  static void __init pnv_pci_init_ioda_phb(struct device_node *np,
 	 * If we're running in kdump kernel, the previous kernel never
 	 * 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.
+	 * transactions from previous kernel. The ppc_pci_reset_phbs
+	 * kernel parameter will force this reset too.
-	if (is_kdump_kernel()) {
+	if (is_kdump_kernel() || pci_reset_phbs) {
 		pr_info("  Issue PHB reset ...\n");
 		pnv_eeh_phb_reset(hose, EEH_RESET_FUNDAMENTAL);
 		pnv_eeh_phb_reset(hose, EEH_RESET_DEACTIVATE);