From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Kocialkowski Subject: Re: [PATCH] ARM: tegra: nyan: Mark all USB ports as host Date: Tue, 08 Nov 2016 10:09:24 +0100 Message-ID: <1478596164.2045.2.camel@paulk.fr> References: <20160918102852.6593-1-contact@paulk.fr> <20161107132854.GF12559@ulmo.ba.sec> <13e7ff98-8bc2-ccf7-94bb-4e1d3c61b20d@nvidia.com> <20161108085420.GG2478@tbergstrom-lnx.Nvidia.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-5Vn7iimBs6YXTAY5PWg3" Return-path: In-Reply-To: <20161108085420.GG2478-Rysk9IDjsxmJz7etNGeUX8VPkgjIgRvpAL8bYrjMMd8@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Peter De Schrijver , Jon Hunter Cc: Thierry Reding , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Stephen Warren , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Alexandre Courbot , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org --=-5Vn7iimBs6YXTAY5PWg3 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Le mardi 08 novembre 2016 =C3=A0 10:54 +0200, Peter De Schrijver a =C3=A9cr= it=C2=A0: > On Mon, Nov 07, 2016 at 02:09:31PM +0000, Jon Hunter wrote: > >=20 > > On 07/11/16 13:28, Thierry Reding wrote: > > > * PGP Signed by an unknown key > > >=20 > > > On Sun, Sep 18, 2016 at 12:28:52PM +0200, Paul Kocialkowski wrote: > > > > Nyan boards only have host USB ports (2 external, 1 internal), ther= e is > > > > no OTG-enabled connector. > > > >=20 > > > > Signed-off-by: Paul Kocialkowski > > > > --- > > > > =C2=A0arch/arm/boot/dts/tegra124-nyan.dtsi | 2 +- > > > > =C2=A01 file changed, 1 insertion(+), 1 deletion(-) > > >=20 > > > Where is this information coming from? I don't have one of the Nyans > > > myself, but one of the Tegra132 devices I have, which I think was > > > derived from one of the Nyans uses one of the external host ports as > > > forced recovery port, for which it would need OTG. > > >=20 > > > I suspect that the way to get U-Boot onto the Nyans is via tegrarcm? > > > In that case I think one of the ports must be OTG. > >=20 > > It is true that the port on the back on the nyan-big can be used with > > recovery mode. I was thinking that this is not a true OTG port as it is > > just a 4-pin type A socket and does not have an ID pin. Thinking some > > more about this the USB spec does include a "Host Negotiation Protocol > > (HNP)" that allows a host and device to swap roles and so keeping it as > > OTG seems valid afterall. >=20 > I don't think the bootrom implements that though. I expect recovery mode > to just program the controller in device mode, without performing any > negotiation. That would make sense. However, if there's a way (even not implemented yet, but a possible way) to= have the kernel configure this port as USB device instead of host dynamically (e= .g. without changing this bit in the dts), then I think it makes sense to keep = the OTG marking and drop this patch. After all, switching to USB device mode doesn't necessarily have to come fr= om the ID pin. --=20 Paul Kocialkowski, developer of free digital technology at the lower levels Website: https://www.paulk.fr/ Coding blog: https://code.paulk.fr/ Git repositories: https://git.paulk.fr/ https://git.code.paulk.fr/ --=-5Vn7iimBs6YXTAY5PWg3 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQIcBAABCAAGBQJYIZZGAAoJEIT9weqP7pUMFoAP/11a0uqqCHwlTd55ILYS6xOl Bin3uYkLs9w+DoCae4SmPcKK+xJCF7y+VdcoJqCexexlm01AVHWP6pvdpz/4+zeU nIHVJpF0Bx8aEQbwubWv0jLiyeCxVk0fHOx/D1o4iMEi363aY6SNwRHPPgiBb2Pf +AnnVl+tZ7zCvH/fivB76p+N3gN1yY1my/7mw9x9lPIVIzK3tYUToGo59v7p1O4g ymjDOQKgXSre+fdmAQHj0uV3dShhdhqurdFxKeMDvVWacVql1Q0c/GOJ1Ih43Lg6 bKE5znLYryC1E3vV2thFD4OAFu09SIhbhvd/SNCieBFeRScVwheO2MfQDPc0Ii9o oaOcyf+Tdc4qcLB68MMGAK1Ba6PMfyemYlIY3XTZFpydMCqIHJkEqWipG7d84YCk hhcInjo3d0gKPwl7Ewq3Jpi/2htsKeKPwO8TNgjpqEEnuSGXBetd0ol72RM1Y3kJ 7fE0BPKD7VH/whgqzcIsC16fy6Ijcny7NObNQuGAGaOAJa+1IpkvJaH+z158sk+A Iu0lDWWYKzmUImc5doVcv27PnEov5YXSnfzBw46yzvXypgyOQuLju14LnIa9xqzo NK9XpLfYL4Zp62RnPgwBj7IkSGSBGT3xGxv3HwPF5G7wsGWK4tG4p1Qy2MAjZ2ou yG3x4V9FMhvN1IKFNd3U =LCEA -----END PGP SIGNATURE----- --=-5Vn7iimBs6YXTAY5PWg3-- -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html