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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 7649DCA9ED3 for ; Tue, 5 Nov 2019 01:03:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 505BA20848 for ; Tue, 5 Nov 2019 01:03:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729788AbfKEBDH (ORCPT ); Mon, 4 Nov 2019 20:03:07 -0500 Received: from mail-pf1-f194.google.com ([209.85.210.194]:44738 "EHLO mail-pf1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729368AbfKEBDH (ORCPT ); Mon, 4 Nov 2019 20:03:07 -0500 Received: by mail-pf1-f194.google.com with SMTP id q26so13830828pfn.11 for ; Mon, 04 Nov 2019 17:03:07 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=1Cw0GA7H4P+NvNZ2CVjOyXYPQ+gLKGTd+sdtcbCWClA=; b=gvFALxDOL1sI8OCkk0CdgEB6K0POvrZ+PSbU6dayE4g6v4FFKH7CNWmzznERuP+wfv ZIzhkqT/x/GNvACsUTdheKAiibO2SEIkFQxbFoyhjTMcvxrR7TG2VunPCnW15uDDEcAs MZSdBdLH+vcvxnk5CN9vuOy87xmFpI1oRA67rB1esbBqTBtpvvtAylTAEuVsKkGPHEnQ kUxxN11kj3dgjSiYZeNlrU8oBfpxhWb1MGbQHW0P55Q2zzxAcWMHEVnjuSTdxlsZ3aeE 02aubH144QM8ysCMlT2MjiW/jYilXtu3UHF6+APpBAlqEPRIABgBfS7K6pRDVWhYGS9R nNeQ== X-Gm-Message-State: APjAAAXoxHWKh1hk1+pcsrpwftmk1wqEcsje5BNDYgMP0/u7ECO9JpdI sJhGzQQJITvq79nqaJpZov8= X-Google-Smtp-Source: APXvYqwreZOoFY0TTqQ+8g4wBcna8GpwQUhre9VXivdAX/qlo3yFFlvkVCnVd3udP5UPmcQ1lEs3+A== X-Received: by 2002:a17:90a:f84:: with SMTP id 4mr2663010pjz.110.1572915786740; Mon, 04 Nov 2019 17:03:06 -0800 (PST) Received: from desktop-bart.svl.corp.google.com ([2620:15c:2cd:202:4308:52a3:24b6:2c60]) by smtp.gmail.com with ESMTPSA id f31sm10146540pjg.31.2019.11.04.17.03.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 04 Nov 2019 17:03:05 -0800 (PST) Subject: Re: [PATCH RFC v2 2/5] ufs: Use reserved tags for TMFs To: Christoph Hellwig Cc: Avri Altman , "James E . J . Bottomley" , "Martin K . Petersen" , linux-scsi@vger.kernel.org, Yaniv Gardi , Subhash Jadavani , Stanley Chu , Tomas Winkler References: <20191105004226.232635-1-bvanassche@acm.org> <20191105004226.232635-3-bvanassche@acm.org> <20191105005729.GA29695@lst.de> From: Bart Van Assche Message-ID: Date: Mon, 4 Nov 2019 17:03:04 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20191105005729.GA29695@lst.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 11/4/19 4:57 PM, Christoph Hellwig wrote: > On Mon, Nov 04, 2019 at 04:42:23PM -0800, Bart Van Assche wrote: >> Reserved tags are numerically lower than non-reserved tags. Compensate the >> change caused by reserving tags by subtracting the number of reserved tags >> from the tag number assigned by the block layer. > > Why would you do that? Do we really care about the exact tag number? > If so would it make sense to reverse in the block layer how we allocate > private vs normal tags? > > Also this change should probably merged into the patch that actually > starts using the private tags by actually allocating requests using > them. Hi Christoph, The UFS driver writes the actual tags into doorbell registers. There are two such doorbell registers: one for regular commands and one for task management functions. Both doorbell registers are bitmasks that start from bit zero. So I don't see how to avoid this kind of tag conversions? From the UFS driver, for regular commands: ufshcd_writel(hba, 1 << task_tag, REG_UTP_TRANSFER_REQ_DOOR_BELL); And for TMFs: ufshcd_writel(hba, 1 << free_slot, REG_UTP_TASK_REQ_DOOR_BELL); Thanks, Bart.