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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 E9A34C04AB8 for ; Fri, 14 Sep 2018 01:53:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AC09620861 for ; Fri, 14 Sep 2018 01:53:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AC09620861 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728381AbeINHFD (ORCPT ); Fri, 14 Sep 2018 03:05:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34238 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726771AbeINHFD (ORCPT ); Fri, 14 Sep 2018 03:05:03 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 30B6B83F4C; Fri, 14 Sep 2018 01:52:57 +0000 (UTC) Received: from ming.t460p (ovpn-8-16.pek2.redhat.com [10.72.8.16]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5FD6760BE0; Fri, 14 Sep 2018 01:52:42 +0000 (UTC) Date: Fri, 14 Sep 2018 09:52:38 +0800 From: Ming Lei To: Adrian Hunter Cc: "Martin K . Petersen" , "James E . J . Bottomley" , Jens Axboe , Christoph Hellwig , Johannes Thumshirn , Bart Van Assche , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, Stanislav Nijnikov , Evan Green , Vinayak Holikatti , Janek Kotas , Vivek Gautam , Asutosh Das , Subhash Jadavani , Sayali Lokhande , Li Wei , Bjorn Andersson , Jaegeuk Kim , Alim Akhtar , Alex Lemberg Subject: Re: [PATCH RFC] scsi: ufs: Disable blk-mq for now Message-ID: <20180914015237.GC11059@ming.t460p> References: <20180913112848.7807-1-adrian.hunter@intel.com> <20180913120459.GA4965@ming.t460p> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.1 (2017-09-22) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Fri, 14 Sep 2018 01:52:58 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 13, 2018 at 03:15:39PM +0300, Adrian Hunter wrote: > On 13/09/18 15:05, Ming Lei wrote: > > On Thu, Sep 13, 2018 at 02:28:48PM +0300, Adrian Hunter wrote: > >> blk-mq does not support runtime pm, so disable blk-mq support for now. > > > > So could you describe a bit what the issue you are trying to fix? > > UFS is a low-power solution, so we must be able to runtime suspend. > > > > > This is host level runtime PM you are trying to address, and if blk-mq > > runtime isn't enabled, I guess the host won't be runtime suspended at all > > because some of its descendant are always active. > > > > So seems we need to do nothing for preventing the host controller from > > entering runtime suspend. > > We don't want to prevent the host controller from runtime suspending, quite > the opposite. OK, got it. However, in previous discussion, it is strongly objected to use per-driver/device .use_blk_mq switch, so not sure if this way can be accepted. BTW, I just posted the runtime PM enablement patches[1] for blk-mq, and I verified that it works fine and passed blktests & xfstest & my other sanity tests, could you try it on UFS? [1] https://marc.info/?l=linux-block&m=153684095523409&w=2 Thanks, Ming