dtoverlay: Reduce size of PCIE IB window in pcie-32-dma overlay

[6by9]

The PCIE inbound window is rounded up to a power of 2, so the default
of 3GB rounds up to 4GB starting at 0. This prohibits the MSI vector
sitting at 0x0_fffffffc, and causes warnings from some subsystems
(eg ahci) of a 64bit address on a 32bit configuration.

Reduce the window down to 2GB to avoid this issue.

#4848

Signed-off-by: Dave Stevenson [email protected]

[pelwell]

LGTM. While you're in there, could you add a comment to fragment 0 saying that it prevents the firmware from rewriting the dma-ranges property?

[6by9]

While you're in there, could you add a comment to fragment 0 saying that it prevents the firmware from rewriting the dma-ranges property?

Done.

[pelwell]

Ta.

[6by9]

Blast. That's thrown up a dtc warning that I hadn't noticed.

..../linux/arch/arm/boot/dts/overlays/pcie-32bit-dma-overlay.dts:26.4-27.27: Warning (dma_ranges_format): /fragment@1/__overlay__:dma-ranges: "dma-ranges" property has invalid length (28 bytes) (parent #address-cells == 2, child #address-cells == 2, #size-cells == 1)

[6by9]

Adding

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

(copied from the pcie0 node) to the fragment clears the warnings, but is that the right answer?

[pelwell]

Yes, that's the right answer because it's the only method I know of. It has the unfortunate side effect of overwriting properties that we shouldn't need to overwrite, but if the values didn't match the base dtb then the dma-ranges would be of the wrong format anyway (which is what the warning is about).