Re: [PATCH v2 05/22] doc: dt-binding: usb: add otg related properties

[Rob Herring <robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Mon, Jun 8, 2015 at 10:02 AM, Li Jun <jun.li-KZfg59tc24xl57MIdRCFDg@public.gmane.org> wrote:
> Add otg version, srp, hnp and adp support for usb OTG port, then those OTG
> features don't have to be decided by usb gadget drivers.
>
> Signed-off-by: Li Jun <jun.li-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
> ---
>  Documentation/devicetree/bindings/usb/generic.txt | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/usb/generic.txt b/Documentation/devicetree/bindings/usb/generic.txt
> index 477d5bb..7386f4a 100644
> --- a/Documentation/devicetree/bindings/usb/generic.txt
> +++ b/Documentation/devicetree/bindings/usb/generic.txt
> @@ -11,6 +11,12 @@ Optional properties:
>                         "peripheral" and "otg". In case this attribute isn't
>                         passed via DT, USB DRD controllers should default to
>                         OTG.
> + - otg-rev: tells usb driver the release number of the OTG and EH supplement
> +                       with which the device and its descriptors are compliant,
> +                       in binary-coded decimal (i.e. 2.0 is 0200H).

I would assume OTG 2.0 is somehow backwards compatible? Is this a h/w
dependency or a driver feature?

> + - srp-support: tells OTG controllers we want to enable SRP.
> + - hnp-support: tells OTG controllers we want to enable HNP.
> + - adp-support: tells OTG controllers we want to enable ADP.

I've recently run into a problem[1] and found that I have to disable
OTG in the kernel to get my device to work. Having to turn-off OTG
seems like the wrong solution, and shifting the problem to DT seems
wrong too. Why is this not a user configurable option (within whatever
h/w constraints there are)?

What are the valid combinations? When do we want these enabled or not?
Wouldn't default enabled be better?

We already have dr_mode property. How is it related to these?

Rob

[1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1047527
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html