Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755369AbbBTTga (ORCPT ); Fri, 20 Feb 2015 14:36:30 -0500 Received: from arroyo.ext.ti.com ([192.94.94.40]:53406 "EHLO arroyo.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754530AbbBTTg2 (ORCPT ); Fri, 20 Feb 2015 14:36:28 -0500 Date: Fri, 20 Feb 2015 13:36:06 -0600 From: Felipe Balbi To: David Cohen CC: Linus Walleij , Robert Baldyga , , MyungJoo Ham , Chanwoo Choi , "linux-kernel@vger.kernel.org" , "linux-usb@vger.kernel.org" , , Subject: Re: [PATCH v2] extcon: otg_gpio: add driver for USB OTG port controlled by GPIO(s) Message-ID: <20150220193606.GA12522@saruman.tx.rr.com> Reply-To: References: <1419288217-19262-1-git-send-email-david.a.cohen@linux.intel.com> <1424375984-26241-1-git-send-email-david.a.cohen@linux.intel.com> <54E6D721.9070107@samsung.com> <20150220191700.GB15303@psi-dev26.jf.intel.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="HlL+5n6rz5pIUxbD" Content-Disposition: inline In-Reply-To: <20150220191700.GB15303@psi-dev26.jf.intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3958 Lines: 106 --HlL+5n6rz5pIUxbD Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Feb 20, 2015 at 11:17:00AM -0800, David Cohen wrote: > Hi Linus and Robert, >=20 > CC'ing Heikki as it involves a RFC from him. >=20 > On Fri, Feb 20, 2015 at 10:53:44AM +0100, Linus Walleij wrote: > > On Fri, Feb 20, 2015 at 7:41 AM, Robert Baldyga = wrote: > > > Hi David, > > > > > > On 02/19/2015 08:59 PM, David Cohen wrote: > > >> Some Intel platforms have an USB OTG port fully (or partially) > > >> controlled by GPIOs: > > >> > > >> (1) USB ID is connected directly to a pulled up GPIO. > > >> > > >> Optionally: > > >> (2) VBUS is enabled/disabled by a GPIO > > >> (3) Platform has 2 USB controllers connected to same port: one for > > >> device and one for host role. D+/- are switched between phys. > > >> according to this GPIO level. > > >> > > >> This driver configures USB OTG port for device or host role accordin= g to > > >> USB ID value. > > >> - If USB ID's GPIO level is low, OTG port is configured for host ro= le > > >> by sourcing VBUS and switching D+/- to host phy. > > >> - If USB ID's GPIO level is high, by standard, the OTG port is > > >> configured for device role by not sourcing VBUS and switching D+/= - to > > >> device controller. > > > > > > IMO it's not very elegant to handle VBUS power on/off in extcon drive= r. > > > Creating fixed regulator would allow to make VBUS handling more gener= ic. >=20 > I agree. But please, see below. >=20 > >=20 > > IMHO it's just layers of abstraction piled on top of each other here. > >=20 > > I would put this adjacent to the phy driver somewhere in drivers/usb/* > > and make the actual USB-driver thing handle its GPIOs directly. > > But I guess David and Felipe have already discussed that as we're > > seeing this patch? >=20 > Felipe suggested to "divide to conquer" instead of having a single > extcon driver to handle all these functions: >=20 > - The mux functions would be controlled by a possible new pinctrl-gpio > driver (Linus, your input here would be nice :) > - The VBUS would be a fixed regulator > - The USB ID would make usage of existent extcon-gpio >=20 > But the on fw side, this is a single ACPI device representing a virtual > device for USB OTG port, which is nothing but a bunch of independent > GPIOs. >=20 > I could make a mfd driver to register devices for those simpler and more > generic drivers, but according to [1] community recognized it as a hack > with ACPI since I'd need to give them the GPIO without requesting on > mfd. >=20 > I'm open for suggestions :) use MFD to create children devices and pass the required data to each one ? --=20 balbi --HlL+5n6rz5pIUxbD Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJU54ymAAoJEIaOsuA1yqRE4YEQAKHjm1cxRrBd0HOKYpjoLWY/ Z5v3fIlTxTNnGnPagrnHvuRp0QAYQolSDxgvlyuq63fEcLFtSdvzrsnw3/wGbJ68 EPhZQsfyHZt+jprlQRDLcE1hIOrxd2isO5O5qILtgOFDiw+SBTpn/uvP1rQaZWzb bT3UPEMjbcZWVBTRUbFycAGpYRd8mtHTxvkcjD4f3Ig+ZAOTIvCg4cvjXkwUPu9F 0MNzrf92utUunBbP2W/LtXEGqy7BnqtVAAE6YdWP7XYGdRW1EpOnnVW5pZUuYaZR 2GEO/OB+sPXs+4BZr4PDn9L94tJ9drSOLPJ9SH/qhZ5rZtXWzrSXBXW17co7ZvNo jUfl6hg9OeZugpSs/Hyi9nEVtr8XDXKRCFsUykkykcEFsWXcVkKeLrhSuHV4I/4z Wt3fBJRy63GbxhLp4HYzTIwYCjgcQzj/lhN+6YTRGffWKM6xXrf8XoQJ2v6M+FEF 58d9RlE7WYblqMWvf4zP32YEaKdG9Yuws2K8UOWhCiC4uvPNHoNkc01Z3S5YBOyi xaSVVQhLHEYE1SgELfbZOHl+5y7xpIiaNGJ+/H7KphcNDJDdYiFZF4zXlxzTD07T dp/SS/VgcjRiJTnzs9CYNewwrvVjr6PzMh5QJTNPbRpAI9yPtSqnMPXjv3QRE32g SxXWSwWy6vYYbqNO/nJ4 =Pw4p -----END PGP SIGNATURE----- --HlL+5n6rz5pIUxbD-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/