Re: [PATCH 11/11] ARM: tegra: pcie: Add device tree support

On 03/08/2012 11:31 PM, Thierry Reding wrote:

* Stephen Warren wrote:

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On 03/08/2012 07:51 AM, Thierry Reding wrote:

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This commit adds support for instantiating the Tegra PCIe controller
from a device tree.

Signed-off-by: Thierry Reding <redacted>

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diff --git a/Documentation/devicetree/bindings/pci/tegra-pcie.txt b/Documentation/devicetree/bindings/pci/tegra-pcie.txt

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+NVIDIA Tegra PCIe controller
+
+Required properties:
+- compatible: "nvidia,tegra20-pcie"
+- reg: physical base address and length of the controller's registers
+- interrupts: the interrupt outputs of the controller
+
+Optional properties:
+- pex-clk-supply: supply voltage for internal reference clock
+- vdd-supply: power supply for controller (1.05V)

Mark, Liam,

Should those *-supply properties really be optional? I got the
impression talking to Mark in a different thread that all regulators
should exist, although their implementation may be via a fixed
regulator, with no GPIO, as determined by the board design.

If I read the TrimSlice code correctly, there is no regulator setup required
to make PCIe work there presumably because they hardwire the proper voltages.

Yes. I believe that's exactly what the fixed regulator is for.

On the other hand, maybe a better solution in this case would be to use the
dummy regulator in those cases.

Mark indicated dummy regulators weren't the preferred mechanism:

http://lkml.org/lkml/2012/2/25/30