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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 34BB1C07E95 for ; Fri, 16 Jul 2021 13:36:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 17D3C613F7 for ; Fri, 16 Jul 2021 13:36:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232841AbhGPNjV (ORCPT ); Fri, 16 Jul 2021 09:39:21 -0400 Received: from mga12.intel.com ([192.55.52.136]:44264 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232808AbhGPNjU (ORCPT ); Fri, 16 Jul 2021 09:39:20 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10046"; a="190410491" X-IronPort-AV: E=Sophos;i="5.84,245,1620716400"; d="scan'208";a="190410491" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Jul 2021 06:36:26 -0700 X-IronPort-AV: E=Sophos;i="5.84,245,1620716400"; d="scan'208";a="506896880" Received: from smile.fi.intel.com (HELO smile) ([10.237.68.40]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Jul 2021 06:36:24 -0700 Received: from andy by smile with local (Exim 4.94.2) (envelope-from ) id 1m4O0o-00EF6N-9y; Fri, 16 Jul 2021 16:36:18 +0300 Date: Fri, 16 Jul 2021 16:36:18 +0300 From: Andy Shevchenko To: David Jeffery Cc: linux-usb@vger.kernel.org, Alan Stern , Laurence Oberman , Ewan Milne , apanagio@redhat.com, torez@redhat.com Subject: Re: [PATCH V2] usb: ehci: Prevent missed ehci interrupts with edge-triggered MSI Message-ID: References: <20210715213744.GA44506@redhat> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210715213744.GA44506@redhat> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Thu, Jul 15, 2021 at 05:37:44PM -0400, David Jeffery wrote: > When MSI is used by the ehci-hcd driver, it can cause lost interrupts which > results in EHCI only continuing to work due to a polling fallback. But the > reliance of polling drastically reduces performance of any I/O through EHCI. > > Interrupts are lost as the EHCI interrupt handler does not safely handle > edge-triggered interrupts. It fails to ensure all interrupt status bits are > cleared, which works with level-triggered interrupts but not the > edge-triggered interrupts typical from using MSI. > > To fix this problem, check if the driver may have raced with the hardware > setting additional interrupt status bits and clear status until it is in a > stable state. > > Signed-off-by: David Jeffery > Tested-by: Laurence Oberman > Reviewed-by: Andy Shevchenko > Acked-by: Alan Stern > Fixes: 306c54d0edb6 usb: hcd: Try MSI interrupts on PCI devices Improper format. Add to your .gitconfig the following: [alias] one = show -s --pretty='format:%h (\"%s\")' c = show -s --pretty='format:https://git.kernel.org/torvalds/c/%h' -- With Best Regards, Andy Shevchenko