Re: [PATCH v2 2/5] usb: chipidea: udc: add OTG status request handling

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On Mon, Mar 16, 2015 at 04:15:22PM +0800, Li Jun wrote:
> On Mon, Mar 16, 2015 at 09:44:30AM +0800, Peter Chen wrote:
> > On Fri, Mar 13, 2015 at 10:34:59AM -0500, Felipe Balbi wrote:
> > > On Fri, Mar 13, 2015 at 11:13:11AM +0800, Peter Chen wrote:
> > > > On Thu, Mar 12, 2015 at 11:04:09AM -0500, Felipe Balbi wrote:
> > > > > 
> > > > > this could still be done generically in composite.c
> > > > > 
> > > > 
> > > > I suggested it at v1, but after thinking more, we have handled
> > > > DEVICE request type at individual udc driver, like remote wakeup,
> > > > self-power support, so it is reasonable we handle get_status that
> > > > if we support hnp polling at udc driver, since it is controller
> > > > driver's capabilities.
> > > 
> > > right, right.. it is controller's capabilities, but all controller needs
> > > to do is a set a flag in struct usb_gadget, which it already does. Then,
> > > every single udc will get free implementation after setting that flag,
> > > right ?
> > > 
> > 
> > Great, then the udc driver which set b_hnp_enable can get the hnp
> > polling capabilities automatically, in fact, hnp polling support
> > is a software implement, I don't think it will affect old v1.3 otg
> > driver.
> > 
> 
> Existing flags in usb_gadget cannot exactly be used for judge if HNP polling
> is supported or not, support HNP does not necessarily means HNP polling is
> supported, in current code you can see b_hnp_enable is set for some controllers
> but they don't support HNP polling yet;

Why HNP polling can't apply for all hnp enabled gadget? It is just a
software feature, once the gadget is at device mode, it should be
ready for hnp, meanwhile, you have already added host_request_flag
at usb_gadget which the user can choose when to enable hnp polling.

> what's more, b_hnp_enable may not be set
> at that time, host may not set b_hnp_enable when enumeration, but wait until the
> host request flag is set in HNP polling, this is different with our host driver
> but meet the recommended sequence in OTG and EH spec 2.0.

That's the problem, please list the spec, we may change when/where to
set b_hnp_enable first if needed.

> 
> So, either we add a new flag for it, or we just do this without flag check(allow
> an OTG device response to HNP polling with 0 even it actually does not support
> HNP polling, which is harmless from what I can see).
> 

Just like I said above, we may have a solution to cover both otg v1.3 and v2.0
first.

-- 

Best Regards,
Peter Chen
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