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=-4.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS autolearn=no 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 8FF4CC33C8C for ; Mon, 6 Jan 2020 16:03:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6481420707 for ; Mon, 6 Jan 2020 16:03:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578326590; bh=0wamf0RnDx+zS5cJm5DjEBVK1GZC3UieZbVnEGReiAQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=jl5CuDdo9xmcAmUFrjOz8wQtOzOV/GciYLEv3CuYvk+LNdxwLMyovmvc3iR0atqci 8AvJV8i3n923+YYdKtplcCTc/4aan/j5LoH12vrZwAbnigdRoNGOwn8F9CfcsI2FN7 hWCBCOvigHGz3lAOU7SxItDIzhXzwcVor0qGh1gA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726477AbgAFQDK (ORCPT ); Mon, 6 Jan 2020 11:03:10 -0500 Received: from mail-lf1-f67.google.com ([209.85.167.67]:40202 "EHLO mail-lf1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726296AbgAFQDJ (ORCPT ); Mon, 6 Jan 2020 11:03:09 -0500 Received: by mail-lf1-f67.google.com with SMTP id i23so36722288lfo.7 for ; Mon, 06 Jan 2020 08:03:08 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=UGKSNhETwLcDVeEssEJo4lDdixB1LJYqjKbjkXT9Qwc=; b=LmZPyV+E69V5TQevGUvekJ58zsBk9me77THHfRblfWMnwlYe3kM7NrS3IDHLVwdgc+ uoZoLCelHOUN6Visp6BF+wO6lt3wORjFRxt3it6TNwBbyZBbWvCJFdUGAP8wv4iBVCqM cVYk1JpB4IKFCx2GPfNBxF4Vm0vDuXocXvx4pQiyVGcb6IXrTMo1n+Ps0rHsBO4GzInR e23AyimGPJnpl+tzZdxxWT+Ugrdf0/BOLeAiJ7tkcmHTf9XPWbYl3dUBBbCzIYRApQOG Nqn0zddknooblx/9s95k0wOeURrYSnfKodMqcz5D4oXItW8Ur4YZkX3EI524ADb3WhFm mSQw== X-Gm-Message-State: APjAAAXmiiaBXnSVf6X5aJtUl1DFL/o79yFvLw6Sra1Mbxi5NzBqimq7 M9Mp29MYkQVSlsy45/6fcqA/ycBZ X-Google-Smtp-Source: APXvYqzmdsi0n/TZbqExidITXwTYOlqYrpu3Tt9gMGyZOpO8s6ZfOd0BNcXqHmDDIeihO5Y+VXefFQ== X-Received: by 2002:a19:c648:: with SMTP id w69mr56822817lff.44.1578326587623; Mon, 06 Jan 2020 08:03:07 -0800 (PST) Received: from xi.terra (c-14b8e655.07-184-6d6c6d4.bbcust.telenor.se. [85.230.184.20]) by smtp.gmail.com with ESMTPSA id d16sm29112409lfa.16.2020.01.06.08.03.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Jan 2020 08:03:06 -0800 (PST) Received: from johan by xi.terra with local (Exim 4.92.3) (envelope-from ) id 1ioUqZ-0001AR-3s; Mon, 06 Jan 2020 17:03:15 +0100 Date: Mon, 6 Jan 2020 17:03:15 +0100 From: Johan Hovold To: Alan Stern Cc: Greg KH , Roger Whittaker , Laurent Pinchart , Takashi Iwai , Johan Hovold , USB list Subject: Re: [PATCH] USB: Fix: Don't skip endpoint descriptors with maxpacket=0 Message-ID: <20200106160315.GA30908@localhost> References: <20200105122846.GA6776@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Mon, Jan 06, 2020 at 10:43:42AM -0500, Alan Stern wrote: > It turns out that even though endpoints with a maxpacket length of 0 > aren't useful for data transfer, the descriptors do serve other > purposes. In particular, skipping them will also skip over other > class-specific descriptors for classes such as UVC. This unexpected > side effect has caused some UVC cameras to stop working. > > In addition, the USB spec requires that when isochronous endpoint > descriptors are present in an interface's altsetting 0 (which is true > on some devices), the maxpacket size _must_ be set to 0. Warning > about such things seems like a bad idea. > > This patch updates an earlier commit which would log a warning and > skip these endpoint descriptors. Now we only log a warning, and we > don't even do that for isochronous endpoints in altsetting 0. > > We don't need to worry about preventing endpoints with maxpacket = 0 > from ever being used for data transfers; usb_submit_urb() already > checks for this. > > Reported-and-tested-by: Roger Whittaker > Fixes: d482c7bb0541 ("USB: Skip endpoints with 0 maxpacket length") > Signed-off-by: Alan Stern > CC: Laurent Pinchart > Link: https://marc.info/?l=linux-usb&m=157790377329882&w=2 Acked-by: Johan Hovold We also need Cc: stable as d482c7bb0541 ("USB: Skip endpoints with 0 maxpacket length") ended up being (auto- ?) selected for stable. Johan