Gary Thomas wrote:
On 02/25/2010 02:03 PM, Scott Wood wrote:
Gary, can you check that the MMIO addresses are going to the PCI bus
as-is, and aren't being translated down to zero? I.e. POTARn should
equal POBARn, and likewise in the device
tree's pci node's ranges.
Hmm, that doesn't match with how I've always had this setup. I have:
POTAR0 = 0x00000000
POTBR0 = 0x000C0000 (0xC0000000 >> 12)
My device tree mappings are:
ranges = <0x02000000 0x0 0xC0000000 0xC0000000 0x0 0x10000000
0x01000000 0x0 0x00000000 0xB8000000 0x0 0x00100000>
That ranges property says that host address 0xc0000000 maps to PCI
address 0xc0000000, so Linux will program the BAR to 0xc0000000, but the
actual accesses will go elsewhere because POTAR0 is zero.
Setting POTAR to zero is also a bad idea because it's aliasing your DMA
window (it may work in certain situations based on who's initiating the
transaction, but it seems like it's asking for trouble), plus it seems
some cards just don't like address zero.
Try setting POTAR0 to 0x000c0000 and see what happens.
-Scott
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