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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 676DDC31E47 for ; Wed, 12 Jun 2019 06:58:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 31AEA205ED for ; Wed, 12 Jun 2019 06:58:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2407719AbfFLG6i (ORCPT ); Wed, 12 Jun 2019 02:58:38 -0400 Received: from mga01.intel.com ([192.55.52.88]:45279 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390376AbfFLG6i (ORCPT ); Wed, 12 Jun 2019 02:58:38 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Jun 2019 23:58:37 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.63,363,1557212400"; d="scan'208";a="184148897" Received: from pipin.fi.intel.com (HELO pipin) ([10.237.72.175]) by fmsmga002.fm.intel.com with ESMTP; 11 Jun 2019 23:58:34 -0700 From: Felipe Balbi To: Alan Stern Cc: Mathias Nyman , Greg Kroah-Hartman , David Howells , viro@zeniv.linux.org.uk, linux-usb@vger.kernel.org, raven@themaw.net, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-block@vger.kernel.org, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 09/10] usb: Add USB subsystem notifications [ver #3] In-Reply-To: References: Date: Wed, 12 Jun 2019 09:58:33 +0300 Message-ID: <87h88v1e92.fsf@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Hi, Alan Stern writes: > On Tue, 11 Jun 2019, Felipe Balbi wrote: > >> >> >> > So for "severe" issues, yes, we should do this, but perhaps not for all >> >> >> > of the "normal" things we see when a device is yanked out of the system >> >> >> > and the like. >> >> >> >> >> >> Then what counts as a "severe" issue? Anything besides enumeration >> >> >> failure? >> >> > >> >> > Not that I can think of at the moment, other than the other recently >> >> > added KOBJ_CHANGE issue. I'm sure we have other "hard failure" issues >> >> > in the USB stack that people will want exposed over time. >> >> >> >> From an XHCI standpoint, Transaction Errors might be one thing. They >> >> happen rarely and are a strong indication that the bus itself is >> >> bad. Either bad cable, misbehaving PHYs, improper power management, etc. >> > >> > Don't you also get transaction errors if the user unplugs a device in >> > the middle of a transfer? That's not the sort of thing we want to sent >> > notifications about. >> >> Mathias, do we get Transaction Error if user removes cable during a >> transfer? I thought we would just get Port Status Change with CC bit >> cleared, no? > > Even if xHCI doesn't give Transaction Errors when a cable is unplugged > during a transfer, other host controllers do. Sometimes quite a lot -- > they continue to occur until the kernel polls the parent hub's > interrupt ep and learns that the port is disconnected, which can take > up to 250 ms. my comment was specific about XHCI. It even started with "From an XHCI standpoint" :-) -- balbi