Re: [PATCH v3 0/6] usb: host: change TPL support behaviour

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On Thu, 4 Sep 2014, Peter Chen wrote:

> On Wed, Sep 03, 2014 at 09:48:15PM -0400, Alan Stern wrote:
> > On Thu, 4 Sep 2014, Peter Chen wrote:
> > 
> > > > > > Hi Greg & Alan, any comments for this patchset?
> > > > > 
> > > > > In patch 2/6, why did you move the !is_targeted(udev) code from 
> > > > > usb_enumerate_device_otg() to usb_enumerate_device()?  Why not leave 
> > > > > the code where it is?
> > > > > 
> > > > 
> > > > TPL support is also needed for embedded host, not only otg host.
> > 
> > But usb_enumerate_device_otg() gets called for all types of 
> > host, right?  At least, it gets called whenever usb_enumerate_device() 
> > runs.
> > 
> > Yes, it contains "#ifdef CONFIG_USB_OTG".  But your patch has "if (... 
> > && IS_ENABLED(CONFIG_USB_OTG))", so the behavior is the same.  Why 
> > move the code if there's no change in behavior?
> > 
> 
> At former code, the tpl support judgement (in function is_targeted) will
> only be called if CONFIG_USB_OTG is defined, but now, we need tpl support
> for all targeted hosts.
> 
> Why we need IS_ENABLED(CONFIG_USB_OTG) as last conditions at if conditions,
> the reason is the operation which the B-device may want switch to host even
> if it is not at A's TPL is only for OTG host.

The only side effect in is_targeted() is the dev_err() message.  Are 
you saying that this dev_err() message needs to appear even when 
CONFIG_USB_OTG is disabled?

Alan Stern

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