Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759565Ab3DDMVT (ORCPT ); Thu, 4 Apr 2013 08:21:19 -0400 Received: from hqemgate03.nvidia.com ([216.228.121.140]:6421 "EHLO hqemgate03.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759464Ab3DDMVR convert rfc822-to-8bit (ORCPT ); Thu, 4 Apr 2013 08:21:17 -0400 X-PGP-Universal: processed; by hqnvupgp07.nvidia.com on Thu, 04 Apr 2013 05:20:21 -0700 From: Venu Byravarasu To: Stephen Warren CC: "gregkh@linuxfoundation.org" , "balbi@ti.com" , "stern@rowland.harvard.edu" , "linux-tegra@vger.kernel.org" , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" Date: Thu, 4 Apr 2013 17:51:09 +0530 Subject: RE: [PATCH v2 1/7] ARM: tegra: finalize USB EHCI and PHY bindings Thread-Topic: [PATCH v2 1/7] ARM: tegra: finalize USB EHCI and PHY bindings Thread-Index: Ac4wnpJ9ntiQGemWSnecVjOwlhE3+gAjjC4Q Message-ID: References: <1364978502-22887-1-git-send-email-vbyravarasu@nvidia.com> <1364978502-22887-2-git-send-email-vbyravarasu@nvidia.com> <515C7E07.4040505@wwwdotorg.org> In-Reply-To: <515C7E07.4040505@wwwdotorg.org> Accept-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US MIME-Version: 1.0 Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2633 Lines: 67 > -----Original Message----- > From: linux-tegra-owner@vger.kernel.org [mailto:linux-tegra- > owner@vger.kernel.org] On Behalf Of Stephen Warren > Sent: Thursday, April 04, 2013 12:38 AM > To: Venu Byravarasu > Cc: gregkh@linuxfoundation.org; balbi@ti.com; > stern@rowland.harvard.edu; linux-tegra@vger.kernel.org; linux- > usb@vger.kernel.org; linux-kernel@vger.kernel.org > Subject: Re: [PATCH v2 1/7] ARM: tegra: finalize USB EHCI and PHY bindings > > On 04/03/2013 02:41 AM, Venu Byravarasu wrote: > > The existing Tegra USB bindings have a few issues: > ... > > This patch fixes the binding definition to resolve these issues. > > > diff --git a/Documentation/devicetree/bindings/usb/nvidia,tegra20-usb- > phy.txt b/Documentation/devicetree/bindings/usb/nvidia,tegra20-usb- > phy.txt > > > Required properties : > ... > > + - vbus-supply: regulator for VBUS > > Doesn't the driver only need to control VBUS if the port is in OTG mode? > > If there is no VBUS control, and the HW provides VBUS, I think that the > port can only operate in host mode. > > If there is no VBUS control, and the HW does not provide VBUS, I think > that the port can only operate in peripheral mode. > > If there is VBUS control, then shouldn't the port always operate in OTG > mode, or are there other reasons to control VBUS even in host-only mode? > > If VBUS control is only useful for OTG mode, then I think the > vbus-supply property should be documented in a "Required properties for > dr_mode == otg" section. Agree, will do it in next patch update. > > I assume that VBUS control makes no sense for a peripheral-mode-only > port, so if VBUS control is useful for host-only mode as well as OTG > mode, then I think the vbus-supply property should be documented in a > "Required properties for dr_mode != peripheral" section. > > Is the following table correct? > > Port operating mode: host peripheral otg > -------------------- ---- ---------- --- > VBUS control required: no no yes > VBUS control useful: yes[1]? no yes > > [1] perhaps for power-saving/suspend??? For waking system up from sleep via devices connected to USB, I think Vbus is always kept ON in host mode. > -- > To unsubscribe from this list: send the line "unsubscribe linux-tegra" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- 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/