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>

diff --git a/arch/mips/pci/pci-bcm1480.c b/arch/mips/pci/pci-bcm1480.c
index 4905d85..f194b4e 100644 (file)
--- 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