Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757319AbcDHBIW (ORCPT ); Thu, 7 Apr 2016 21:08:22 -0400 Received: from mail-pa0-f68.google.com ([209.85.220.68]:36493 "EHLO mail-pa0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756819AbcDHBIT (ORCPT ); Thu, 7 Apr 2016 21:08:19 -0400 Date: Fri, 8 Apr 2016 09:01:30 +0800 From: Peter Chen To: Roger Quadros Cc: Felipe Balbi , stern@rowland.harvard.edu, gregkh@linuxfoundation.org, peter.chen@freescale.com, dan.j.williams@intel.com, jun.li@freescale.com, mathias.nyman@linux.intel.com, tony@atomide.com, Joao.Pinto@synopsys.com, abrestic@chromium.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org Subject: Re: [PATCH v6 01/12] usb: hcd: Initialize hcd->flags to 0 Message-ID: <20160408010130.GA9070@shlinux2.ap.freescale.net> References: <1459865117-7032-1-git-send-email-rogerq@ti.com> <1459865117-7032-2-git-send-email-rogerq@ti.com> <87zit72rqz.fsf@intel.com> <5704AD76.9080806@ti.com> <20160407094246.GA9963@shlinux2.ap.freescale.net> <57063915.7000700@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <57063915.7000700@ti.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: 1717 Lines: 45 On Thu, Apr 07, 2016 at 01:40:21PM +0300, Roger Quadros wrote: > On 07/04/16 12:42, Peter Chen wrote: > > On Wed, Apr 06, 2016 at 09:32:22AM +0300, Roger Quadros wrote: > >> On 06/04/16 09:09, Felipe Balbi wrote: > >>> > >>> Hi, > >>> > >>> Roger Quadros writes: > >>>> diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c > >>>> index 2ca2cef..6b1930d 100644 > >>>> --- a/drivers/usb/core/hcd.c > >>>> +++ b/drivers/usb/core/hcd.c > >>>> @@ -2706,6 +2706,7 @@ int usb_add_hcd(struct usb_hcd *hcd, > >>>> int retval; > >>>> struct usb_device *rhdev; > >>>> > >>>> + hcd->flags = 0; > >>> > > > > I am not sure if this usb_add(remove)_hcd pair is safe and clean enough > > for start/stop host role. From my point, we may need to do like > > .probe/.remove host platform driver interface. In that case, we can make > > probe and remove are meant to be called from bus layer. > I do not see a way how OTG framework can call probe/remove of HCD driver. > Some HCDs may be platform devices, some PCI, so different entities are calling > the HCD .probe hook. > > > sure the clocks and regulators are off, and hcd will be zero-initialized > > why can't we make that sure that is taken care of within the hcd_ops? > Why should some driver keep its regulators and clocks enabled when hcd is stopped? > It doesn't need to. If it is doing so now, it needs to be fixed. > Well, you may misunderstand me. I mean your hcd_ops->start or ->stop is hard to be a general one which only calls usb_hcd_add or usb_hcd_remove. It needs to implement like .probe or .remove at platform driver, some example code like host_start and host_stop at drivers/usb/chipidea/host.c. -- Best Regards, Peter Chen