On Wed, Apr 20, 2016 at 11:15:30AM +0300, Roger Quadros wrote: > On 19/04/16 04:56, Peter Chen wrote: > > On Mon, Apr 18, 2016 at 10:11:29AM -0400, Alan Stern wrote: > >> On Mon, 18 Apr 2016, Peter Chen wrote: > >> > >>> On Wed, Apr 06, 2016 at 09:32:22AM +0300, Roger Quadros wrote: > >>>> On 06/04/16 09:09, Felipe Balbi wrote: > >>>>> > >>>>> Hi, > >>>>> > >>>>> Roger Quadros <rogerq@xxxxxx> writes: > >>>>>> diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c > >>>>>> index 2ca2cef..6b1930d 100644 > >>>>>> --- a/drivers/usb/core/hcd.c > >>>>>> +++ b/drivers/usb/core/hcd.c > >>>>>> @@ -2706,6 +2706,7 @@ int usb_add_hcd(struct usb_hcd *hcd, > >>>>>> int retval; > >>>>>> struct usb_device *rhdev; > >>>>>> > >>>>>> + hcd->flags = 0; > >>>>> > >>>>> seems like this would make more sense in usb_del_hcd() instead. > >>>>> > >>>> > >>>> OK, I'll move it there. > >>>> > >>> > >>> It depends on Alan's comments, whether only usb_add_hcd/usb_del_hcd > >>> pair can be called repeat. If Alan acks it, I have no idea for it. > >> > >> Most of the host controller drivers were not written with this in mind, > >> but I think it would be a good thing to allow. It would speed up the > >> host/device role switches. > >> > >> This might mean we need to fix up several drivers to make them work > >> correctly in an OTG environment. It should be possible to do this. Is > >> there any particular reason why it would be difficult for Chipidea? > >> > > > > I just want to do clean remove at OTG environment, like rmmod, so I did > > this when I worked on chipidea OTG design. > > I am worried if there are some resources dedicated for host device, eg, > > clocks, gpio. etc. > > > > If OTG framework can know well hcd's add and remove, it is ok for chipidea > > just calling usb_add_hcd/usb_del_hcd currently, but I suggested roger > > adding platform hcd_ops as optional parameter in case the platform > > has special requirement for hcd_ops. > > > We have 2 users now, omap + dwc3 and sh + EHCI/OHCI and we didn't seem to > observe any issues with the usb_add/del_hcd approach. > > Let's keep things minimal for now. In the future, if users need something more > we can always extend the framework. > I agree -- Best Regards, Peter Chen -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
