Re: [PATCH 4/9] PCI: mvebu: add support for reset on GPIO

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[Added DT maintainers directly for a question below]

On 08/13/13 02:56, Kumar Gala wrote:
On Aug 12, 2013, at 1:46 PM, Sebastian Hesselbarth wrote:

This patch adds a check for DT passed reset-gpios property and deasserts/
asserts reset pin on probe/remove with configurable delay. Corresponding
binding documentation is also updated.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx>
[...]
diff --git a/Documentation/devicetree/bindings/pci/mvebu-pci.txt b/Documentation/devicetree/bindings/pci/mvebu-pci.txt
index 638673a..f2fa261 100644
--- a/Documentation/devicetree/bindings/pci/mvebu-pci.txt
+++ b/Documentation/devicetree/bindings/pci/mvebu-pci.txt
@@ -76,6 +76,8 @@ and the following optional properties:
- marvell,pcie-lane: the physical PCIe lane number, for ports having
   multiple lanes. If this property is not found, we assume that the
   value is 0.
+- reset-gpios: optional gpio to PERST#
+- reset-delay-ms: delay in ms to wait after reset de-assertion

Both of these should probably be marvell,reset...

Kumar,

as Thomas already mentioned, non-prefixed "foo-gpios" are quite common.
As reset gpios are likely to be common among SoC pci controller setups,
I though I'd stick with the non-prefixed property. But I have no strong
opinion about it - but let's see how DT jurisdiction will vote :)

Does reset-delay-ms vary per board? I can't remember where the
discussion got to about configuration info.

Hmm, for Dove SoC, I only have one board to test - but the driver
currently is for 4 different SoCs. I just did some quick evaluation
of the reset delay required to bring up the device on the D3Plug.
Using 10ms was too short, 20ms worked.

I guess there will be other SoC/boards requiring different delays
but I am fine with hardcoded 20ms and re-introduce reset-delay property
only if it is really required. The driver's default is 20ms anyway.


Example:

It's usually good to update example to show all optional properties.

Ok, will add the properties to one of the example ports.

Thanks,

Sebastian

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