From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 89884C43387 for ; Wed, 16 Jan 2019 13:44:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 62440206C2 for ; Wed, 16 Jan 2019 13:44:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2393295AbfAPNom (ORCPT ); Wed, 16 Jan 2019 08:44:42 -0500 Received: from mail.bootlin.com ([62.4.15.54]:60094 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733175AbfAPNol (ORCPT ); Wed, 16 Jan 2019 08:44:41 -0500 Received: by mail.bootlin.com (Postfix, from userid 110) id 7519720955; Wed, 16 Jan 2019 14:44:39 +0100 (CET) Received: from windsurf (aaubervilliers-681-1-37-87.w90-88.abo.wanadoo.fr [90.88.156.87]) by mail.bootlin.com (Postfix) with ESMTPSA id 2D3A820728; Wed, 16 Jan 2019 14:44:29 +0100 (CET) Date: Wed, 16 Jan 2019 14:44:29 +0100 From: Thomas Petazzoni To: Paul Kocialkowski Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Peter Chen , Greg Kroah-Hartman Subject: Re: [PATCH] usb: chipidea: Grab the (legacy) USB PHY by phandle first Message-ID: <20190116144429.7df1d0c5@windsurf> In-Reply-To: <554a5b4f463df6551846cfdc3b043d3f1d99381f.camel@bootlin.com> References: <20190116101051.21202-1-paul.kocialkowski@bootlin.com> <20190116115350.3daa9b4f@windsurf> <554a5b4f463df6551846cfdc3b043d3f1d99381f.camel@bootlin.com> Organization: Bootlin X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Wed, 16 Jan 2019 14:30:28 +0100, Paul Kocialkowski wrote: > > Why is this conditional on the generic PHY lookup failing? > > > > Don't we simply want: > > > > ci->phy = devm_phy_get(dev->parent, "usb-phy"); > > ci->usb_phy = devm_usb_get_phy_by_phandle(dev->parent, "phys", 0); > > if (IS_ERR(ci->usb_phy)) > > ci->usb_phy = devm_usb_get_phy(dev->parent, USB_PHY_TYPE_USB2); > > > > ? > > Well, the code dealing with the PHY later on will use ci->phy over ci- > >usb_phy (so generic PHY API first). As a result, if the > devm_usb_get_phy_by_phandle lookup fails but we got a generic PHY, the > latter will be used and there is no need for a fallback. That's why I > put both conditions there. Maybe that's too much of an assumption? Well prior to your code, there was already a possibility for both ci->phy and ci->usb_phy to be valid. I don't think it's really useful to avoid the fallback when a generic PHY has already been found, it's confusing. If really you want to clarify that, it should be: /* Let's first try to find a generic PHY */ ci->phy = devm_phy_get(dev->parent, "usb-phy"); if (IS_ERR(ci->phy)) { /* Fall back to legacy USB PHY */ ci->usb_phy = devm_usb_get_phy_by_phandle(dev->parent, "phys", 0); if (IS_ERR(ci->usb_phy)) ci->usb_phy = devm_usb_get_phy(dev->parent, USB_PHY_TYPE_USB2); } With that, you would only have either ci->phy or ci->usb_phy be valid, and never both. With your change, you can have ci->phy and ci->usb_phy both be valid if the legacy USB PHY was found using devm_usb_get_phy_by_phandle(), but not if we fell back to devm_usb_get_phy(). > > Does this needs a "Fixes:" tag ? It's not fixing a regression because > > nobody complained until now, but it's really fixing a behavior that > > wasn't correct. > > Yes I it this makes sense to consider that this was incorrect behavior > starting from the moment the dt bindings were formalized for the > driver, which would be commit d7d30c911dd957e274c3da6910d4286862ab1d78. > > Do you think that would nake sense? Up to the maintainer I'd say. I don't have any preference here. Thomas -- Thomas Petazzoni, CTO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com