[PATCH v2 2/3] ehci-platform: Add support for controllers with multiple reset lines

Am Freitag, den 11.12.2015, 19:28 +0100 schrieb Hans de Goede:
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diff --git a/Documentation/devicetree/bindings/usb/usb-ehci.txt b/Documentation/devicetree/bindings/usb/usb-ehci.txt
index a12d601..0701812 100644
--- a/Documentation/devicetree/bindings/usb/usb-ehci.txt
+++ b/Documentation/devicetree/bindings/usb/usb-ehci.txt

@@ -18,7 +18,7 @@ Optional properties:
   - clocks : a list of phandle + clock specifier pairs
   - phys : phandle + phy specifier pair
   - phy-names : "usb"
- - resets : phandle + reset specifier pair
+ - resets : a list of phandle + reset specifier pairs

Are there documented names for these resets?

This binding is a generic ehci controller binding, so even if
the names are documented for the allwinner SoC we should
not use names, just like the binding is deliberately not
using names for the clocks either to keep it generic, so
that we can reuse the binding + driver with many different SoCs.

I know, I'm just interested in understanding why this is necessary ...

quoted

Is the companion you
mention the Port Control?

Sort of, with USB-2, USB-1 compatibility is handled via a mux on the
datalines (controlled by the EHCI controller Port Control) which muxes
the lines to an USB-1 controller (typically either UHCI or OHCI) when the
device does not connect after USB-2 highspeed handshaking.

This USB-1 controller (or controller_S_ in some case since the
USB-1 companions may have less root-ports per controller then the EHCI
has root-ports) is called the companion controller.

The 2 controllers are supposed to be 100% independent but on the H3
Allwinner has done something (not documented) which requires one to
deassert reset on both before you can talk to either one.

... so thank you for the explanation.

Acked-by: Philipp Zabel <p.zabel@pengutronix.de>

regards
Philipp