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

[Li Jun <b47624-KZfg59tc24xl57MIdRCFDg@public.gmane.org>]

On Fri, Jun 12, 2015 at 11:31:02AM +0300, Roger Quadros wrote:
> 
> 
> 
> Agreed. We still need to determine legacy platform if
> none of the features are set.
> 
> How about defining the followong enum for gadget->xyz_support
> 
> enum otg_feature {
> 	OTG_FEATURE_UNDEFINED = 0,
> 	OTG_FEATURE_ENABLED,
> 	OTG_FEATURE_DISABLED,
> };
> 
> for legacy platforms this will be UNDEFINED for all so you can detect it
> and continue legacy behaviour i.e. enable HNP/SRP, disable ADP.
> 
> For new platforms at least one of them won't be UNDEFINED so you can
> enable the feature if ENABLED and disable if UNDEFINED/DISABLED.
> 
> We can still keep disable flags so that users can disable all 3 OTG features
> while in OTG mode.
> 
> cheers,
> -roger

Regarding use of "xyz-disable" flags:
After more thinking this, I just realize that we can use "otg-rev" property
to handle the case of none of xyz-disable properties passed, for legacy
platforms, the new "otg-rev" not passed either, so it's a legacy platform,
if new platform does support all 3 features(SRP/HNP/ADP), the otg-rev
should be passed and also should be 2.0 or above, because ADP is
introduced in OTG 2.0(maybe that's why in current gadget driver, only
enable SRP/HNP).

So:
1) new platform with full otg feature support:
dr_mode = "otg";
otg-rev = "0x0200";

2) legacy platform
dr_mode = "otg"

Then I think we are okay to use disable flags.

thanks
Li Jun
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