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=-0.7 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 573D1C636CB for ; Fri, 16 Jul 2021 17:27:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 32EB1613FD for ; Fri, 16 Jul 2021 17:27:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231231AbhGPRai (ORCPT ); Fri, 16 Jul 2021 13:30:38 -0400 Received: from mga11.intel.com ([192.55.52.93]:31673 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229803AbhGPRah (ORCPT ); Fri, 16 Jul 2021 13:30:37 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10047"; a="207740154" X-IronPort-AV: E=Sophos;i="5.84,245,1620716400"; d="scan'208";a="207740154" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Jul 2021 10:27:41 -0700 X-IronPort-AV: E=Sophos;i="5.84,245,1620716400"; d="scan'208";a="431281124" Received: from smile.fi.intel.com (HELO smile) ([10.237.68.40]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Jul 2021 10:27:40 -0700 Received: from andy by smile with local (Exim 4.94.2) (envelope-from ) id 1m4Rcc-00EK4B-1t; Fri, 16 Jul 2021 20:27:34 +0300 Date: Fri, 16 Jul 2021 20:27:34 +0300 From: Andy Shevchenko To: Ralf Ramsauer Cc: Jiri Slaby , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Greg Kroah-Hartman Subject: Re: [EXT] Re: [PATCH v1 3/4] serial: 8250_pci: Always try MSI/MSI-X Message-ID: References: <20210713104026.58560-1-andriy.shevchenko@linux.intel.com> <20210713104026.58560-3-andriy.shevchenko@linux.intel.com> <9af24b96-8119-7ccf-f0d0-d725af80aa0b@kernel.org> <784629f9-677e-ee53-aceb-89397ce0951a@oth-regensburg.de> <599a37bd-3cb4-1e4b-d5f8-936c4daae71f@oth-regensburg.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <599a37bd-3cb4-1e4b-d5f8-936c4daae71f@oth-regensburg.de> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 16, 2021 at 05:27:36PM +0200, Ralf Ramsauer wrote: > On 16/07/2021 17:01, Andy Shevchenko wrote: > > On Fri, Jul 16, 2021 at 4:07 PM Ralf Ramsauer > > wrote: > >> On 14/07/2021 15:35, Andy Shevchenko wrote: > >>> On Wed, Jul 14, 2021 at 3:56 PM Ralf Ramsauer > >>> wrote: > >>>> On 14/07/2021 08:54, Jiri Slaby wrote: > >>>>> On 13. 07. 21, 12:40, Andy Shevchenko wrote: > >>> > >>>>> Hmm, have you checked the commit which introduced the whitelist? > >>>>> > >>>>> Nevertheless, this needs to handled with care: while many 8250 devices > >>>>> actually claim to support MSI(-X) interrupts it should not be > >>>>> enabled be > >>>>> default. I had at least one device in my hands with broken MSI > >>>>> implementation. > >>>>> > >>>>> So better introduce a whitelist with devices that are known to support > >>>>> MSI(-X) interrupts. I tested all devices mentioned in the patch. > >>>>> > >>>>> > >>>>> You should have at least CCed the author for an input. > >>>> > >>>> Yep, back then I was testing three different 8250 pci cards. All of them > >>>> claimed to support MSI, while one really worked with MSI, the one that I > >>>> whitelisted. So I thought it would be better to use legacy IRQs as long > >>>> as no one tested a specific card to work with MSI. > >>> > >>> Can you shed a light eventually what those cards are? > > > >> So I found a no-name el-cheapo card that has some issues with MSI: > > > > Win Chip Head (WCH) > > > >> 18:00.0 Serial controller: Device 1c00:3253 (rev 10) (prog-if 05 [16850]) Thank you! One more thing, ist it possible to see entire PCI configuration space (w/ or w/o MSI, I don't think it matters)? Something like `lspci -nk -vvv -xxx -s 18:0` to run. (I believe there are a lot of 0xff bytes) -- With Best Regards, Andy Shevchenko