From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1752112AbdJEK4E (ORCPT <rfc822;w@1wt.eu>);
        Thu, 5 Oct 2017 06:56:04 -0400
Received: from mailout4.samsung.com ([203.254.224.34]:39162 "EHLO
        mailout4.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1751500AbdJEKzz (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 5 Oct 2017 06:55:55 -0400
X-AuditID: b6c32a39-a6fff7000000109f-a9-59d60fb8aaad
From: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Linus Walleij <linus.walleij@linaro.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        linux-mmc <linux-mmc@vger.kernel.org>,
        linux-block <linux-block@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Bough Chen <haibo.chen@nxp.com>,
        Alex Lemberg <alex.lemberg@sandisk.com>,
        Mateusz Nowak <mateusz.nowak@intel.com>,
        Yuliy Izrailov <Yuliy.Izrailov@sandisk.com>,
        Jaehoon Chung <jh80.chung@samsung.com>,
        Dong Aisheng <dongas86@gmail.com>,
        Das Asutosh <asutoshd@codeaurora.org>,
        Zhangfei Gao <zhangfei.gao@gmail.com>,
        Sahitya Tummala <stummala@codeaurora.org>,
        Harjani Ritesh <riteshh@codeaurora.org>,
        Venu Byravarasu <vbyravarasu@nvidia.com>,
        Shawn Lin <shawn.lin@rock-chips.com>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH V9 13/15] mmc: block: Add CQE and blk-mq support
Date: Thu, 05 Oct 2017 12:55:49 +0200
Message-id: <2081590.uFvUN0fvNT@amdc3058>
User-Agent: KMail/4.13.3 (Linux/3.13.0-96-generic; KDE/4.13.3; x86_64; ; )
In-reply-to: <CAPDyKFrVK2hK9LEPKRfTTMOvP6WD5ug+VTwOt9tDaiMKKUBsNA@mail.gmail.com>
MIME-version: 1.0
Content-transfer-encoding: 7Bit
Content-type: text/plain; charset="us-ascii"
X-Brightmail-Tracker: H4sIAAAAAAAAA02Se0hTURzHO3e7d1drdbs+OvgoGQhp5SMSTmpWIHELAzWi9I9y5E0tp7ap
        qCDNolk2X5gaQ0JSMB8p6tT5pk03C0pNHSo+QwWVRiFL08TcroL/fX7n+/2d75fDIXn0KO5E
        xiUks9IEcbyIsOW36jx8zmmOGSN81hfPo88LdQSamNsgULdiQIC2m0sJlD9WDVB1bT+GxjcV
        OHrzrwpD3ZNn0EhHGYH6dvIBytqYxlDv6hCOphYacDSsXhMgw8c76Ie2kIe0xQMEelY1g12x
        Y0bycjGmXTUtYCq6ljFmythFMJ0TcoLJfW4imEaTBmO2Vb18Jk9dA5iSukGMWWs6GXo40jYw
        mo2PS2Wl3kFRtrGKD0N40jKR1vWzAJeDFjwH2JCQugBnP03yc4AtSVMaACfNRQJuWAdwfGOJ
        t+/arNYBTugEUNmqw7jBDOCrrRnrXQTlDwuza4CF7anTsGt+ELeYeNQiDiuzqgQWwY4Khkvm
        SivzKXdYoGy1RggpDyjXyAkLO1A3oLonG7OwDXULjk38xjjPcbhRNMO3MI86BXt6i3GOz8Kv
        +nprPUjpBfD19FuC6x0Ml8v69tgOrhjUu8HkLjvD7/2XuONSANu2ILfbDGBNZ4GAEwKgzjC8
        F3AUmsxKnNsVwpcKmkMG6nMknPsqNKxO7z1dFgYNX35hBcBVdaC26kBt1YHa5YBXAxzZJJkk
        hpX5Jvl5ycQSWUpCjNeDREkTsP41z4saoP8WogUUCURHhIfmRiNoXJwqS5doASR5InuhaGcs
        ghZGi9MzWGnifWlKPCvTAmeSLzohdGgw3qWpGHEy+5hlk1jpvoqRNk5ykHFvB2/3enrbYLyW
        Jg2XlL8fTu1/omrbccnMVCnX3jXNtgeYFSM0texP0+Gj4dc7RMJHbuWNPRKTTr2m/2NcYV3K
        /laFOeKOvqGZDjfdXkRlu9dW5A67lggbwrwNzoFheKDJL+py5OZYi1EV+HBepAzB6oPcnbem
        Gtt7Z+NEfFms2NeTJ5WJ/wPHAigSZwMAAA==
X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrHIsWRmVeSWpSXmKPExsVy+t9jAd0d/NciDa4eZbQ4+WQNm8XNBz/Y
        LPa2nWC3+Lt5OptF/9WVjBYrVx9lsrjxq43VYsqf5UwWe29pW1zeNYfN4sj/fkaLxh93mSz2
        v77AanHnyXpWi4tbPrNbHF8bbvHo0ERmi0NTT7BZNC2/x+Qg7HG5r5fJY+esu+wei/e8ZPK4
        c20Pm8fumw1sHr3N79g8Nr7bweTxd9Z+Fo++LasYPaatOc/k8XmTXAB3FJdNSmpOZllqkb5d
        AldG24oLrAUv2Sr2vJ3A2sC4lbWLkZNDQsBE4tfKw4xdjFwcQgI7GSW27F3IBuF8ZZTY+/Q1
        C0gVm4CVxMT2VYwgtoiAhsSeh+dZQYqYBV6zSqx5MI8JJCEs4CLx7OsSdhCbRUBVYkLPNmYQ
        m1dAU6JhRwMbiC0q4CWxZV87WD2nQLBEx9Q9LBDb1jJK/Lr1F6pBUOLH5Htgm5kF5CX27Z/K
        CmFrSazfeZxpAiP/LCRls5CUzUJStoCReRWjZGpBcW56brFRgWFearlecWJucWleul5yfu4m
        RmAsbjus1beD8f6S+EOMAhyMSjy8EY+uRAqxJpYVV+YeYpTgYFYS4VX6fzVSiDclsbIqtSg/
        vqg0J7X4EKM0B4uSOO/tvGORQgLpiSWp2ampBalFMFkmDk6pBka/nLNRNudXHSvRqLrvejpt
        kbWLTNatq9t9eRYdPe0+Q7GxZaVW3s/XvAlmm1imBkfa/zkUMHXSA52PVyUnt+3b/8fAVTvQ
        fK/1ac0OXT6eB0eao9f27GNYFCDxftq6/aJ+rQ1v1LyZjm9sjRA6rluhvvUAE0/zrqw9HdOu
        JDA4mj+Q3lWlslaJpTgj0VCLuag4EQCGBVw3wQIAAA==
X-CMS-MailID: 20171005105552epcas1p45c58d8d356f029a0089271b903af3e48
X-Msg-Generator: CA
X-Sender-IP: 182.195.42.142
X-Local-Sender: =?UTF-8?B?QmFydGxvbWllaiBab2xuaWVya2lld2ljehtTUlBPTC1LZXJu?=
        =?UTF-8?B?ZWwgKFRQKRvsgrzshLHsoITsnpAbU2VuaW9yIFNvZnR3YXJlIEVuZ2luZWVy?=
X-Global-Sender: =?UTF-8?B?QmFydGxvbWllaiBab2xuaWVya2lld2ljehtTUlBPTC1LZXJu?=
        =?UTF-8?B?ZWwgKFRQKRtTYW1zdW5nIEVsZWN0cm9uaWNzG1NlbmlvciBTb2Z0d2FyZSBF?=
        =?UTF-8?B?bmdpbmVlcg==?=
X-Sender-Code: =?UTF-8?B?QzEwG0VIURtDMTBDRDAyQ0QwMjczOTI=?=
CMS-TYPE: 101P
X-CMS-RootMailID: 20171005105552epcas1p45c58d8d356f029a0089271b903af3e48
X-RootMTR: 20171005105552epcas1p45c58d8d356f029a0089271b903af3e48
References: <1506083824-4024-1-git-send-email-adrian.hunter@intel.com>
        <2384661.GfpEZ6rEzz@amdc3058>
        <CAPDyKFrVK2hK9LEPKRfTTMOvP6WD5ug+VTwOt9tDaiMKKUBsNA@mail.gmail.com>
        <CGME20171005105552epcas1p45c58d8d356f029a0089271b903af3e48@epcas1p4.samsung.com>
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wednesday, October 04, 2017 11:48:27 AM Ulf Hansson wrote:
> [...]
> 
> >> MQ code that doesn't perform and therefore we cannot switch seamlessly
> >> to MQ.
> >
> > I think that switching seamlessly to blk-mq in short/medium-term
> > is not possible (SCSI tried and failed to do so). The changes to
> > the old path are very complex and besides affecting performance
> > they also affect error recovery handling (which needs to be tested
> > properly before the switch).
> 
> Agreed, and that's why I have queued up the new Kconfig option for
> enabling the blkmq path from MMC.

This seems premature - the new Kconfig option change for "mmc-mq" should
belong to the patch adding "mmc-mq" support (otherwise it may just confuse
users who enable it).

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics