[PATCH v6 18/42] powerpc/powernv: Allocate PE# in deasending order

[Gavin Shan]

The available PE#, represented by a bitmap in the PHB, is allocated
in ascending order. It conflicts with the fact that M64 segments are
assigned in same order. In order to avoid the conflict, the patch
allocates PE# in descending order.

Signed-off-by: Gavin Shan <gwshan at linux.vnet.ibm.com>
---
 arch/powerpc/platforms/powernv/pci-ioda.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 56b058c..1c950e8 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -161,13 +161,18 @@ static struct pnv_ioda_pe *pnv_ioda_reserve_pe(struct pnv_phb *phb, int pe_no)
 static struct pnv_ioda_pe *pnv_ioda_alloc_pe(struct pnv_phb *phb)
 {
 	unsigned long pe;
+	unsigned long limit = phb->ioda.total_pe_num - 1;
 
 	do {
 		pe = find_next_zero_bit(phb->ioda.pe_alloc,
-					phb->ioda.total_pe_num, 0);
-		if (pe >= phb->ioda.total_pe_num)
+					phb->ioda.total_pe_num, limit);
+		if (pe < phb->ioda.total_pe_num &&
+		    !test_and_set_bit(pe, phb->ioda.pe_alloc))
+			break;
+
+		if (--limit >= phb->ioda.total_pe_num)
 			return NULL;
-	} while(test_and_set_bit(pe, phb->ioda.pe_alloc));
+	} while (1);
 
 	return pnv_ioda_init_pe(phb, pe);
 }
-- 
2.1.0