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 AA8CFC433EF for ; Wed, 4 May 2022 14:40:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351430AbiEDOoO (ORCPT ); Wed, 4 May 2022 10:44:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56708 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344317AbiEDOoJ (ORCPT ); Wed, 4 May 2022 10:44:09 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 777616147; Wed, 4 May 2022 07:40:33 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 1C0CF61A9C; Wed, 4 May 2022 14:40:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 47618C385A4; Wed, 4 May 2022 14:40:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1651675232; bh=pXEMqJc4FMTugFCsqdvFsuG1NQYrw+IcXscCZBtoAmQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=poZyFfi/B3gq6L6NFEBuYPHvtwbfB7IYSgRGeftkd/+88cA4KuFAt/JFIRgp/qC29 3ZqgPAzgHH9W/VdxK0kiocFMLzhpRohjJ7dLs90/Pr5d85rdkZy0Qi+n1kgZaF0FWX Y0a5/2cnRJ8cOdM/Yarnsw50+1OFUhgJU6CtAoj0= Date: Wed, 4 May 2022 16:40:31 +0200 From: Greg KH To: Alan Stern 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-kernel@vger.kernel.org On Tue, May 03, 2022 at 11:48:33AM -0400, Alan Stern wrote: > On Tue, May 03, 2022 at 05:27:08PM +0200, Geert Uytterhoeven wrote: > > Hi Alan, > > > > On Tue, May 3, 2022 at 5:14 PM Alan Stern wrote: > > > On Tue, May 03, 2022 at 12:14:30PM +0200, Geert Uytterhoeven wrote: > > > > On Sat, 23 Apr 2022, Alan Stern wrote: > > > > > This patch adds a "gadget" bus and uses it for registering gadgets and > > > > > their drivers. From now on, bindings will be managed by the driver > > > > > core rather than through ad-hoc manipulations in the UDC core. > > > > > > > > > > As part of this change, the driver_pending_list is removed. The UDC > > > > > core won't need to keep track of unbound drivers for later binding, > > > > > because the driver core handles all of that for us. > > > > > > > > > > However, we do need one new feature: a way to prevent gadget drivers > > > > > from being bound to more than one gadget at a time. The existing code > > > > > does this automatically, but the driver core doesn't -- it's perfectly > > > > > happy to bind a single driver to all the matching devices on the bus. > > > > > The patch adds a new bitflag to the usb_gadget_driver structure for > > > > > this purpose. > > > > > > > > > > A nice side effect of this change is a reduction in the total lines of > > > > > code, since now the driver core will do part of the work that the UDC > > > > > used to do. > > > > > > > > > > A possible future patch could add udc devices to the gadget bus, say > > > > > as a separate device type. > > > > > > > > > > Signed-off-by: Alan Stern > > > > > > > > Thanks for your patch, which is now commit fc274c1e997314bf ("USB: > > > > gadget: Add a new bus for gadgets") in usb-next. > > > > > > > > This patch cause a regression on the Renesas Salvator-XS development > > > > board, as R-Car H3 has multiple USB gadget devices: > > > > > > Then these gadgets ought to have distinct names in order to avoid the > > > conflict below: > > > > > > > sysfs: cannot create duplicate filename '/bus/gadget/devices/gadget' > > > > CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.18.0-rc1-arm64-renesas-00074-gfc274c1e9973 #1587 > > > > Hardware name: Renesas Salvator-X 2nd version board based on r8a77951 (DT) > > > > Call trace: > > > > dump_backtrace+0xcc/0xd8 > > > > show_stack+0x14/0x30 > > > > dump_stack_lvl+0x88/0xb0 > > > > dump_stack+0x14/0x2c > > > > sysfs_warn_dup+0x60/0x78 > > > > sysfs_do_create_link_sd.isra.0+0xe4/0xf0 > > > > sysfs_create_link+0x20/0x40 > > > > bus_add_device+0x64/0x110 > > > > device_add+0x31c/0x850 > > > > usb_add_gadget+0x124/0x1a0 > > > > usb_add_gadget_udc_release+0x1c/0x50 > > > > usb_add_gadget_udc+0x10/0x18 > > > > renesas_usb3_probe+0x450/0x728 > > > ... > > > > > > Having three gadget devices, all named "gadget", doesn't seem like a > > > good idea. > > > > I'm not so sure where these names are coming from. > > `git grep '"gadget"'` points to the following likely targets: > > > > drivers/usb/gadget/udc/core.c: dev_set_name(&gadget->dev, "gadget"); > > drivers/usb/renesas_usbhs/mod_gadget.c: gpriv->mod.name = "gadget"; > > > > Changing both names reveals the problem is actually caused by > > the former ;-) > > Ah, good. > > One way to attack this would be to keep a static counter and dynamically > set the name to "gadget.%d" using the counter's value. Or keep a bitmap > of allocated gadget numbers and use the first available number. > > Felipe, Greg, any opinions? Just use an idr structure for the number, that's the simplest way to track that. thanks, greg k-h