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 5101BC433EF for ; Tue, 3 May 2022 10:14:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233924AbiECKSJ (ORCPT ); Tue, 3 May 2022 06:18:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35406 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233116AbiECKSH (ORCPT ); Tue, 3 May 2022 06:18:07 -0400 Received: from albert.telenet-ops.be (albert.telenet-ops.be [IPv6:2a02:1800:110:4::f00:1a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3A001EC56 for ; Tue, 3 May 2022 03:14:34 -0700 (PDT) Received: from ramsan.of.borg ([IPv6:2a02:1810:ac12:ed40:cd2b:85eb:bdf:a9c3]) by albert.telenet-ops.be with bizsmtp id SAEX270023SeZYW06AEXpV; Tue, 03 May 2022 12:14:31 +0200 Received: from geert (helo=localhost) by ramsan.of.borg with local-esmtp (Exim 4.93) (envelope-from ) id 1nlpY6-002rGb-P5; Tue, 03 May 2022 12:14:30 +0200 Date: Tue, 3 May 2022 12:14:30 +0200 (CEST) From: Geert Uytterhoeven X-X-Sender: geert@ramsan.of.borg To: Alan Stern cc: Felipe Balbi , Greg KH , USB mailing list , linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/4] USB: gadget: Add a new bus for gadgets In-Reply-To: Message-ID: References: User-Agent: Alpine 2.22 (DEB 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Alan, 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: 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 platform_probe+0x64/0xd0 really_probe+0x100/0x2a0 __driver_probe_device+0x74/0xd8 driver_probe_device+0x3c/0xe0 __driver_attach+0x80/0x110 bus_for_each_dev+0x6c/0xc0 driver_attach+0x20/0x28 bus_add_driver+0x138/0x1e0 driver_register+0x60/0x110 __platform_driver_register+0x24/0x30 renesas_usb3_driver_init+0x18/0x20 do_one_initcall+0x15c/0x31c kernel_init_freeable+0x2f0/0x354 kernel_init+0x20/0x120 ret_from_fork+0x10/0x20 renesas_usb3: probe of ee020000.usb failed with error -17 ... renesas_usbhs: probe of e6590000.usb failed with error -17 After boot-up, only one gadget device is visible: root@h3-salvator-xs:~# ls -l /sys/bus/gadget/devices/ total 0 lrwxrwxrwx 1 root root 0 Feb 14 2019 gadget -> ../../../devices/platform/soc/e659c000.usb/gadget root@h3-salvator-xs:~# Reverting this patch fixes the issue. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds