From mboxrd@z Thu Jan 1 00:00:00 1970 From: Li Jun Subject: Re: [PATCH v2 01/22] usb: add OTG version number in usb_otg_descriptor Date: Wed, 10 Jun 2015 21:53:37 +0800 Message-ID: <20150610135336.GA9443@shlinux2> References: <20150609135130.GA20453@shlinux1.ap.freescale.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Alan Stern Cc: Roger Quadros , Li Jun , gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, balbi-l0cyMroinI0@public.gmane.org, peter.chen-KZfg59tc24xl57MIdRCFDg@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, pawel.moll-5wv7dgnIgG8@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, macpaul-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org List-Id: devicetree@vger.kernel.org On Tue, Jun 09, 2015 at 10:16:23AM -0400, Alan Stern wrote: > On Tue, 9 Jun 2015, Li Jun wrote: > > > > > -/* USB_DT_OTG (from OTG 1.0a supplement) */ > > > > +/* USB_DT_OTG */ > > > > struct usb_otg_descriptor { > > > > __u8 bLength; > > > > __u8 bDescriptorType; > > > > > > > > __u8 bmAttributes; /* support for HNP, SRP, etc */ > > > > + struct bcdOTG otg_rev[0]; > > > > > > why not just __le16 bcdOTG here ? > > > > usb_otg_descriptor of OTG 1.0 and 2.0 have different size, if directly add > > __le16 bcdOTG here, then it cannot used for OTG 1.0. > > I use a zero length array as Peter suggested here for bcdOTG, then the size > > of usb_otg_descriptor is still 3(not 5), which is compliant with OTG 1.x, if OTG > > 2.0 or later, we can use member of otg_rev to add bcdOTG, then the size > > of usb_otg_descriptor + bcdOTG will be 5, in one word, I want to use existing > > usb_otg_descriptor struct to cover both OTG 1.x and 2.0 > > In the end, you may find it is simpler to use two different > structures: usb_otg_descriptor and usb_otg_20_descriptor. > Try it and see. That should be, I will try your suggested approach, thanks. Li Jun > > Alan Stern > -- 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