pci-expmem-hack

    
CFE 1.2.5 and earlier fails to turn on the ExpMemEn bit in the
PCIFeatureControl register, which means that DMA does not work
beyond physical address 01_0000_0000, ergo to DRAM beyond 1GB.
    
With ExpMemEn turned on, 01_0000_0000-0f_ffff_ffff is mapped,
so DMA works for up to 61 GB of DRAM.
    
Will be fixed in CFE 1.2.6 (yet to be released).
    
Signed-Off-By: Andy Isaacson <adi@broadcom.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/arch/mips/pci/pci-bcm1480.c b/arch/mips/pci/pci-bcm1480.c
index 4905d8593d6d..f194b4e4f86a 100644
--- a/arch/mips/pci/pci-bcm1480.c
+++ b/arch/mips/pci/pci-bcm1480.c
@@ -232,6 +232,14 @@ static int __init bcm1480_pcibios_init(void)
                 bcm1480_bus_status |= PCI_BUS_ENABLED;
         }
 
+        /* turn on ExpMemEn */
+        cmdreg = READCFG32(CFGOFFSET(0, PCI_DEVFN(PCI_BRIDGE_DEVICE, 0), 0x40));
+        printk("PCIFeatureCtrl = %x\n", cmdreg);
+        WRITECFG32(CFGOFFSET(0, PCI_DEVFN(PCI_BRIDGE_DEVICE, 0), 0x40),
+                        cmdreg | 0x10);
+        cmdreg = READCFG32(CFGOFFSET(0, PCI_DEVFN(PCI_BRIDGE_DEVICE, 0), 0x40));
+        printk("PCIFeatureCtrl = %x\n", cmdreg);
+
         /*
          * Establish mappings in KSEG2 (kernel virtual) to PCI I/O
          * space.  Use "match bytes" policy to make everything look