Re: [PATCH v2 07/10] ARM: tegra: pcie: Add device tree support

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On 6/12/2012 10:19 PM, Thierry Reding wrote:
On Tue, Jun 12, 2012 at 10:05:35PM -1000, Mitch Bradley wrote:
On 6/12/2012 9:52 PM, Thierry Reding wrote:
I think the configuration spaces and downstream I/O ranges need to be in the
pcie-controller's reg property because they are remapped and used by the
controller driver, not by the individual ports.

That's probably not really necessary but rather a result of how the driver
was written. Perhaps the driver should handle them differently instead,
listing the regions in the ranges property of the parent and listing the
corresponding partitions in the ranges properties of the pci child nodes.

Like in the following, where the ranges property of the ports partition the
ranges passed from the parent evenly:

	pcie-controller {
		compatible = "nvidia,tegra20-pcie";
		reg =<0x80003000 0x00000800   /* PADS registers */
		       0x80003800 0x00000200>; /* AFI registers */
		interrupts =<0 98 0x04   /* controller interrupt */
			      0 99 0x04>; /* MSI interrupt */
		status = "disabled";

		ranges =<0x80000000 0x80000000 0x00002000   /* 2 root ports */
			  0x80004000 0x80004000 0x00100000   /* configuration space */
			  0x80104000 0x80100000 0x00100000   /* extended configuration space */
			  0x80400000 0x80400000 0x00010000   /* downstream I/O */
			  0x90000000 0x90000000 0x10000000   /* non-prefetchable memory */
			  0xa0000000 0xa0000000 0x10000000>; /* prefetchable memory */

		#address-cells =<1>;
		#size-cells =<1>;

		pci@80000000 {
			reg =<0x80000000 0x00001000>;
			status = "disabled";

			#address-cells =<3>;
			#size-cells =<2>;

			ranges =<0x80400000 0x80400000 0x00008000   /* I/O */
				  0x90000000 0x90000000 0x08000000   /* non-prefetchable memory */
				  0xa0000000 0xa0000000 0x08000000>; /* prefetchable memory */

You are on the right track here, but the format of the child-address
portion of the above ranges property is incorrect.  Since the child
address space is the PCI address space, the child-address portion
needs to be 3 cells.  It's not a linear address but rather a triple.
The first cell identifies the address type (config, I/O, memory..)
and the second and third cells are offsets within that subspace.
The second and third cells will typically be 0.  The PCI binding has
details.

Also, the size field in ranges is specified according to the child address space, so there must be 2 size cells in the ranges at this level. Each ranges entry at this level is:

<child_address_space, child_address_high, child_address_low, parent_address, child_size_high, child_size_low>

The above should be:

			ranges =<0x81000000 0 0  0x80400000  0 0x00008000   /* I/O */
				 0x82000000 0 0  0x90000000  0 0x08000000   /* non-prefetchable memory */
				 0xc2000000 0 0  0xa0000000  0 0x08000000>; /* prefetchable memory */




Okay, I'll need to read up some more.

Thanks,
Thierry
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