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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C47D7C433EF for ; Mon, 9 May 2022 16:47:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239372AbiEIQvT (ORCPT ); Mon, 9 May 2022 12:51:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38284 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239369AbiEIQvQ (ORCPT ); Mon, 9 May 2022 12:51:16 -0400 Received: from netrider.rowland.org (netrider.rowland.org [192.131.102.5]) by lindbergh.monkeyblade.net (Postfix) with SMTP id 283B222241A for ; Mon, 9 May 2022 09:47:19 -0700 (PDT) Received: (qmail 131135 invoked by uid 1000); 9 May 2022 12:47:19 -0400 Date: Mon, 9 May 2022 12:47:19 -0400 From: Alan Stern To: Greg KH Cc: Geert Uytterhoeven , Felipe Balbi , USB mailing list , Linux-Renesas , Linux Kernel Mailing List , Yoshihiro Shimoda Subject: Re: [PATCH 4/4] USB: gadget: Add a new bus for gadgets Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Mon, May 09, 2022 at 06:23:31PM +0200, Greg KH wrote: > On Mon, May 09, 2022 at 11:05:06AM -0400, Alan Stern wrote: > > On Mon, May 09, 2022 at 04:42:01PM +0200, Geert Uytterhoeven wrote: > > > Hi Alan, > > > > > > On Mon, May 9, 2022 at 4:15 PM Alan Stern wrote: > > > > On Mon, May 09, 2022 at 09:46:25AM +0200, Geert Uytterhoeven wrote: > > > > > > Geert: > > > > > > > > > > > > Can you test the patch below? It ought to fix the problem (although it > > > > > > > > > > Thanks! > > > > > > > > > > root@h3-salvator-xs:~# ls -l /sys/bus/gadget/devices/ > > > > > total 0 > > > > > lrwxrwxrwx 1 root root 0 Feb 14 2019 gadget.0 -> > > > > > ../../../devices/platform/soc/e659c000.usb/gadget.0 > > > > > lrwxrwxrwx 1 root root 0 Feb 14 2019 gadget.1 -> > > > > > ../../../devices/platform/soc/ee020000.usb/gadget.1 > > > > > lrwxrwxrwx 1 root root 0 Feb 14 2019 gadget.2 -> > > > > > ../../../devices/platform/soc/e6590000.usb/gadget.2 > > > > > > > > > > Tested-by: Geert Uytterhoeven > > > > > > > > > > LGTM, so > > > > > Reviewed-by: Geert Uytterhoeven > > > > > > > > Thanks! > > > > > > > > > > might end up causing other problems down the line...) > > > > > > > > > > Can you please elaborate? I'm not too familiar with UBS gadgets. > > > > > > > > I was concerned about the fact that changing the name of a file, > > > > directory, or symbolic link in sysfs means changing a user API, and so > > > > it might cause some existing programs to fail. That would be a > > > > regression. > > > > > > > > Perhaps the best way to work around the problem is to leave the name set > > > > to "gadget" if the ID number is 0, while adding the ID number on to the > > > > name if the value is > 0. What do you think? > > > > > > Oh, you mean the "gadget.N" subdirs, which are the targets of the > > > symlinks above? These were indeed named "gadget" before. > > > > > > Would it be possible to append the ".N" suffixes only to the actual > > > symlinks, while keeping the target directory names unchanged? > > > E.g. /sys/bus/gadget/devices/gadget.0 -> > > > ../../../devices/platform/soc/e659c000.usb/gadget > > > > No, it's not possible. Or at least, not without significant changes to > > the driver core. Besides, people expect these names to be the same. > > It should always be ok to change the names of devices as those are not > going to be persistent / determinisitic. It's the attributes of devices > that are supposed to be used to determine those types of things. > > So I think let's start out with the .N suffix for everything for now. > I'll be glad to submit the fixed patch to the Android kernel build > system to see what their testing comes back with to see if they happened > to make any name assumptions as that's the largest user of this > codebase. Okay. Do you need me to send it as a proper patch before you try it out? Alan Stern