[PATCH 1/4] USB: Fix of_usb_get_dr_mode_by_phy with a shared phy block

Hans de Goede hdegoede at redhat.com
Fri Jun 3 03:34:35 PDT 2016


On 02-06-16 20:16, Bin Liu wrote:
> Hi,
> On Thu, Jun 02, 2016 at 07:31:03PM +0200, Hans de Goede wrote:
>> Some SoCs have a single phy-hw-block with multiple phys, this is
>> modelled by a single phy dts node, so we end up with multiple
>> controller nodes with a phys property pointing to the phy-node
>> of the otg-phy.
>> Only one of these controllers typically is an otg controller, yet we
> Is it guaranteed that only one of them will be otg?

I guess not, but if there are 2 then with my patch we are of no worse
then today, we will then pick the first otg controller. Whereas
of_usb_get_dr_mode_by_phy currently is broken even on setups with
a shared phy dt-node and only 1 otg controller, which are quite

I believe it is unlikely that there will be more then 1 otg controller,
so I believe that we should not worry about this until we actually
hit this problem.

>> were checking the first controller who uses a phy from the block and>> then end up looking for a dr_mode property in e.g. the ehci controller.
>> Instead of looking for nodes with a phy property, look for nodes
>> with a dr_mode property, so that we actually access the dr_mode property
>> in a node which has it.
> Quote from Documentation/devicetree/bindings/usb/generic.txt:
> "- dr_mode: ...
> 		In case this attribute isn't
> 		passed via DT, USB DRD controllers should default to
> 		OTG."
> So it is not mandatory to define dr_mode in DT, then you wouldn't be
> able to find the controller in such case.

If no controller is found then of_usb_get_dr_mode_by_phy will return
USB_DR_MODE_UNKNOWN, just like it does today for controller nodes which
do not set dr_mode.

So in this case my patch does not change anything.



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