From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752560AbbAVNdP (ORCPT ); Thu, 22 Jan 2015 08:33:15 -0500 Received: from bear.ext.ti.com ([192.94.94.41]:40553 "EHLO bear.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752437AbbAVNdK (ORCPT ); Thu, 22 Jan 2015 08:33:10 -0500 Message-ID: <54C0FBDC.6040803@ti.com> Date: Thu, 22 Jan 2015 15:32:12 +0200 From: Roger Quadros User-Agent: Mozilla/5.0 (X11; Linux i686; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: CC: , , , , , , , , Subject: Re: [PATCH 0/5] extcon: usb: Introduce USB GPIO extcon driver. Fix DRA7 USB. References: <1421689942-10201-1-git-send-email-rogerq@ti.com> <20150120190237.GG15169@saruman> In-Reply-To: <20150120190237.GG15169@saruman> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Felipe, On 20/01/15 21:02, Felipe Balbi wrote: > On Mon, Jan 19, 2015 at 07:52:17PM +0200, Roger Quadros wrote: >> Hi, >> >> On DRA7 EVMs the USB ID pin is connected to a GPIO line. The USB drivers >> (dwc3 + dwc3-omap) depend on extcon framework to get the USB cable state >> (USB or USB-Host) to put the controller in the right mode. >> >> There were earlier attempts [1] to get this working by trying to patch up >> the existing GPIO extcon driver. >> >> This series attemts to take a different approach by introducing a new >> USB specific extcon driver to handle the USB ID GPIO pin and >> interpret a right USB cable state. >> >> The reasoning to introduce this new driver is: >> 1) The existing GPIO extcon driver doesn't understand USB cable states >> and it can't handle more than one cable per instance. >> >> For the USB case we need to handle at least 2 cable states. >> a) USB (attach/detach) >> b) USB-Host (attach/detach) >> and could possible include more states like >> c) Fast-charger (attach/detach) >> d) Slow-charger (attach/detach) >> >> 2) This USB specific driver can be easily updated in the future to >> handle VBUS events, or charger detect events, in case it happens >> to be available on GPIO for any platform. >> >> 3) The DT implementation is very easy. You just need one extcon node per USB >> instead of one extcon node per cable state as in case of [1]. >> >> 4) The cable state string doesn't need to be encoded in the device tree >> as in case of [1]. >> >> 5) With only ID event available, you can simulate a USB-peripheral attach >> when USB-Host is detacted instead of hacking the USB driver to do the same. >> >> Tested on DRA7-evm and DRA72-evm. > > while at that, you might want to patch X15 too. > USB2 port is meant for peripheral use only. ID pin from USB port is not connected to GPIO. cheers, -roger