[ARM] 3089/1: ixp4xx AHB/PCI endianness fix

Patch from Alessandro Zummo

  This patch fixes AHB/PCI endianness problems when the
 processor is in little-endian mode.

 The patch configures the CSR register closely following the directives
 in [1], paragraph 4.1, page 19.

 According to the considerations in [1], page 11, while the AHB bus
 supports both endian modes, on the IXP4XX it always uses big-endian.

 The PCI bus is connected to the South AHB. A wrong setting in the CSR
 register will thus cause a malfunctional PCI bus.

 A schematic diagram of the bus interconnections on the IXP4XX
 can be found in [1], page 18.

 The patch has been verified to work on the NSLU2 in
 both LE and BE modes.

 The author is Peter Korsgaard.

 [1] Intel® IXP4XX Product Line of Network Processors and IXC1100
 Control Plane Processor:
 Understanding Big Endian and Little Endian Modes

 http://www.intel.com/design/network/applnots/25423701.pdf

Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Deepak Saxena <dsaxena@plexity.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/mach-ixp4xx/common-pci.c b/arch/arm/mach-ixp4xx/common-pci.c
index 2b54436..9795da2 100644 (file)
--- a/arch/arm/mach-ixp4xx/common-pci.c
+++ b/arch/arm/mach-ixp4xx/common-pci.c
@@ -427,7 +427,7 @@ void __init ixp4xx_pci_preinit(void)
 #ifdef __ARMEB__
        *PCI_CSR = PCI_CSR_IC | PCI_CSR_ABE | PCI_CSR_PDS | PCI_CSR_ADS;
 #else
-       *PCI_CSR = PCI_CSR_IC;
+       *PCI_CSR = PCI_CSR_IC | PCI_CSR_ABE;
 #endif
 
        pr_debug("DONE\n");