Hi,

Richard Zhao writes:

On Tue, Jul 03, 2012 at 10:22:37AM +0800, Peter Chen wrote:

quoted

quoted

Hmm. I think it'd be reasonable to use dr_mode like the other bindings,
and have the default case be decided by the ID pin when dr_mode isn't
specified. Having different defaults for different bindings seems pretty
reasonable to me.

As far as I know, there is no USB Spec says the ID value should be
used at device or host mode. At USB device and host driver, there
should be NO ID related things, that is to say device or host driver
should not care ID is grounded or floated, as ID may be grounded
at device mode, and high at host mode for different board design.
ID interrupt should only be enabled when dr_mode = otg;

I don't quite understand your point. All the discussions are based
on otg controllers.

quoted

Board design and customized usage (user may want to use only device mode
for otg capable port) makes what USB role will be used
at driver, so dr_mode at dts (or pdata->dr_mode at non-dt solution) can make
the decision for driver how USB role will be used.

That's the case we need the property. But for fine otg hw design, we
don't need the property, right?

And to decide whether it's otg controller or not, the driver read the
capability registers.

A user may wish to restrict even a 'fine otg hw design' to be used in
pure host or device mode. That's where the dr_mode property jumps in.


Lothar Wa?mann
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