From mboxrd@z Thu Jan 1 00:00:00 1970 From: LW@KARO-electronics.de (=?utf-8?Q?Lothar_Wa=C3=9Fmann?=) Date: Tue, 3 Jul 2012 09:02:40 +0200 Subject: [PATCH v2 3/4] usb: chipidea: ci13xxx-imx: add "dr_mode" property to device tree bindings In-Reply-To: <20120703030049.GA3374@b20223-02.ap.freescale.net> References: <1340891629-13145-1-git-send-email-mkl@pengutronix.de> <1340891629-13145-4-git-send-email-mkl@pengutronix.de> <20120629014352.GA28923@b20223-02.ap.freescale.net> <4FED5D77.3050009@pengutronix.de> <20120629084509.GB28923@b20223-02.ap.freescale.net> <4FEDCF15.9040000@wwwdotorg.org> <20120630011906.GA2489@richard-laptop> <4FF1FEBC.3040107@wwwdotorg.org> <20120703030049.GA3374@b20223-02.ap.freescale.net> Message-ID: <20466.39184.844238.739308@ipc1.ka-ro> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, Richard Zhao writes: > On Tue, Jul 03, 2012 at 10:22:37AM +0800, Peter Chen wrote: > > > Hmm. I think it'd be reasonable to use dr_mode like the other bindings, > > > and have the default case be decided by the ID pin when dr_mode isn't > > > specified. Having different defaults for different bindings seems pretty > > > reasonable to me. > > > > As far as I know, there is no USB Spec says the ID value should be > > used at device or host mode. At USB device and host driver, there > > should be NO ID related things, that is to say device or host driver > > should not care ID is grounded or floated, as ID may be grounded > > at device mode, and high at host mode for different board design. > > ID interrupt should only be enabled when dr_mode = otg; > I don't quite understand your point. All the discussions are based > on otg controllers. > > > > Board design and customized usage (user may want to use only device mode > > for otg capable port) makes what USB role will be used > > at driver, so dr_mode at dts (or pdata->dr_mode at non-dt solution) can make > > the decision for driver how USB role will be used. > That's the case we need the property. But for fine otg hw design, we > don't need the property, right? > > And to decide whether it's otg controller or not, the driver read the > capability registers. > A user may wish to restrict even a 'fine otg hw design' to be used in pure host or device mode. That's where the dr_mode property jumps in. Lothar Wa?mann -- ___________________________________________________________ Ka-Ro electronics GmbH | Pascalstra?e 22 | D - 52076 Aachen Phone: +49 2408 1402-0 | Fax: +49 2408 1402-10 Gesch?ftsf?hrer: Matthias Kaussen Handelsregistereintrag: Amtsgericht Aachen, HRB 4996 www.karo-electronics.de | info at karo-electronics.de ___________________________________________________________