pcibios_setup_bridge() is normally called to update PCI bridge
windows. It allocates PE for PCI buses. However it is not called
on a root bus which does not have an upstream bridge.

This reserves PE# for a root bus in advance. This will be used in
the subsequent patch to do setup.

Signed-off-by: Gavin Shan <gws...@linux.vnet.ibm.com>
---
 arch/powerpc/platforms/powernv/pci-ioda.c | 30 +++++++++++++++++++++++++++++-
 arch/powerpc/platforms/powernv/pci.h      |  1 +
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c 
b/arch/powerpc/platforms/powernv/pci-ioda.c
index 1c950e8..8aa6ab8 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -236,6 +236,13 @@ static int pnv_ioda1_init_m64(struct pnv_phb *phb)
                pr_warn("  Cannot strip M64 segment for reserved PE#%d\n",
                        phb->ioda.reserved_pe_idx);
 
+       /* Strip off the M64 segment corresponding to the PE#
+        * for PCI root bus, which is last supported PE# or
+        * (reserved PE# - 1).
+        */
+       if (phb->ioda.root_pe_idx != IODA_INVALID_PE)
+               r->end -= phb->ioda.m64_segsize;
+
        return 0;
 
 fail:
@@ -293,6 +300,13 @@ static int pnv_ioda2_init_m64(struct pnv_phb *phb)
                pr_warn("  Cannot strip M64 segment for reserved PE#%d\n",
                        phb->ioda.reserved_pe_idx);
 
+       /* Strip off the M64 segment corresponding to the PE#
+        * for PCI root bus, which is last supported PE# or
+        * (reserved PE# - 1).
+        */
+       if (phb->ioda.root_pe_idx != IODA_INVALID_PE)
+               r->end -= phb->ioda.m64_segsize;
+
        return 0;
 
 fail:
@@ -3237,7 +3251,21 @@ static void __init pnv_pci_init_ioda_phb(struct 
device_node *np,
        aux = memblock_virt_alloc(size, 0);
        phb->ioda.pe_alloc = aux;
        phb->ioda.pe_array = aux + pemap_off;
-       set_bit(phb->ioda.reserved_pe_idx, phb->ioda.pe_alloc);
+
+       /* Choose number of PE for root bus, which shouldn't consume
+        * any M64 resource. So we avoid picking low-end PE#, which
+        * is usually bound with M64 resources closely.
+        */
+       pnv_ioda_reserve_pe(phb, phb->ioda.reserved_pe_idx);
+       if (phb->ioda.reserved_pe_idx == 0) {
+               phb->ioda.root_pe_idx = phb->ioda.total_pe_num - 1;
+               pnv_ioda_reserve_pe(phb, phb->ioda.root_pe_idx);
+       } else if (phb->ioda.reserved_pe_idx == (phb->ioda.total_pe_num - 1)) {
+               phb->ioda.root_pe_idx = phb->ioda.reserved_pe_idx - 1;
+               pnv_ioda_reserve_pe(phb, phb->ioda.root_pe_idx);
+       } else {
+               phb->ioda.root_pe_idx = IODA_INVALID_PE;
+       }
 
        INIT_LIST_HEAD(&phb->ioda.pe_dma_list);
        INIT_LIST_HEAD(&phb->ioda.pe_list);
diff --git a/arch/powerpc/platforms/powernv/pci.h 
b/arch/powerpc/platforms/powernv/pci.h
index fc899cd..e93a489 100644
--- a/arch/powerpc/platforms/powernv/pci.h
+++ b/arch/powerpc/platforms/powernv/pci.h
@@ -135,6 +135,7 @@ struct pnv_phb {
                struct {
                        /* Global bridge info */
                        unsigned int            total_pe_num;
+                       unsigned int            root_pe_idx;
                        unsigned int            reserved_pe_idx;
 
                        /* 32-bit MMIO window */
-- 
2.1.0

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