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=-8.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 AE11EC433E2 for ; Mon, 14 Sep 2020 20:14:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 886E420E65 for ; Mon, 14 Sep 2020 20:14:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726011AbgINUOG (ORCPT ); Mon, 14 Sep 2020 16:14:06 -0400 Received: from netrider.rowland.org ([192.131.102.5]:58295 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1725926AbgINUOF (ORCPT ); Mon, 14 Sep 2020 16:14:05 -0400 Received: (qmail 978548 invoked by uid 1000); 14 Sep 2020 16:14:03 -0400 Date: Mon, 14 Sep 2020 16:14:03 -0400 From: Alan Stern To: Matthias Kaehlcke Cc: Greg Kroah-Hartman , Rob Herring , Frank Rowand , Krzysztof Kozlowski , Bastien Nocera , Ravi Chandra Sadineni , linux-usb@vger.kernel.org, Stephen Boyd , devicetree@vger.kernel.org, Douglas Anderson , Peter Chen , linux-kernel@vger.kernel.org, "Alexander A. Klimov" , Masahiro Yamada Subject: Re: [PATCH 2/2] USB: misc: Add onboard_usb_hub driver Message-ID: <20200914201403.GA977844@rowland.harvard.edu> References: <20200914112716.1.I248292623d3d0f6a4f0c5bc58478ca3c0062b49a@changeid> <20200914112716.2.I7c9a1f1d6ced41dd8310e8a03da666a32364e790@changeid> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200914112716.2.I7c9a1f1d6ced41dd8310e8a03da666a32364e790@changeid> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Mon, Sep 14, 2020 at 11:27:49AM -0700, Matthias Kaehlcke wrote: > The main issue this driver addresses is that a USB hub needs to be > powered before it can be discovered. For onboard hubs this is often > solved by supplying the hub with an 'always-on' regulator, which is > kind of a hack. Some onboard hubs may require further initialization > steps, like changing the state of a GPIO or enabling a clock, which > requires further hacks. This driver creates a platform device > representing the hub which performs the necessary initialization. > Currently it only supports switching on a single regulator, support > for multiple regulators or other actions can be added as needed. > Different initialization sequences can be supported based on the > compatible string. > > Besides performing the initialization the driver can be configured > to power the hub off during system suspend. This can help to extend > battery life on battery powered devices, which have no requirements > to keep the hub powered during suspend. The driver can also be > configured to leave the hub powered when a wakeup capable USB device > is connected when suspending, and keeping it powered otherwise. > > Technically the driver consists of two drivers, the platform driver > described above and a very thin USB driver that subclasses the > generic hub driver. Actually it subclasses the generic usb device driver, not the hub driver. > The purpose of this driver is to provide the > platform driver with the USB devices corresponding to the hub(s) > (a hub controller may provide multiple 'logical' hubs, e.g. one > to support USB 2.0 and another for USB 3.x). > > Co-developed-by: Ravi Chandra Sadineni > Signed-off-by: Ravi Chandra Sadineni > Signed-off-by: Matthias Kaehlcke > --- > This is an evolution of '[RFC] USB: misc: Add usb_hub_pwr driver' > (https://lore.kernel.org/patchwork/patch/1299239/). > > Changes in v1: > - renamed the driver to 'onboard_usb_hub' > - single file for platform and USB driver > - USB hub devices register with the platform device > - the DT includes a phandle of the platform device > - the platform device now controls when power is turned off > - the USB driver became a very thin subclass of the generic hub > driver > - enabled autosuspend support See https://marc.info/?l=linux-usb&m=159914635920888&w=2 and the accompanying submissions. You'll probably want to include those updates in your driver. Alan Stern