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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 F25CDC34031 for ; Wed, 19 Feb 2020 02:35:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C677B2176D for ; Wed, 19 Feb 2020 02:35:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="TyqEqJrq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727880AbgBSCfa (ORCPT ); Tue, 18 Feb 2020 21:35:30 -0500 Received: from mail27.static.mailgun.info ([104.130.122.27]:21494 "EHLO mail27.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726761AbgBSCfa (ORCPT ); Tue, 18 Feb 2020 21:35:30 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1582079729; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=jXPj6BmmHK1fbvzmEuD+DaWJ8U2v+ztHn2qwHyzklAE=; b=TyqEqJrqReb0laK8uveazUTV41WxKHrDrr+aIrMmZBq2lLOZlRM3zP6Cp6a63eqBT78627j0 8dNE+drBbN8BUqTR+GvQk3Xv8cUTYrvSP4v0IHRwzePZBVZJEsMHhOtj6eArYDsbAhdakpUw sq5G8iaJDM8ycLzUkspQLPg5KFI= X-Mailgun-Sending-Ip: 104.130.122.27 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by mxa.mailgun.org with ESMTP id 5e4c9ef0.7f5b20aab3e8-smtp-out-n03; Wed, 19 Feb 2020 02:35:28 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 706D4C447A2; Wed, 19 Feb 2020 02:35:28 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: cang) by smtp.codeaurora.org (Postfix) with ESMTPSA id 90523C433A2; Wed, 19 Feb 2020 02:35:27 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Wed, 19 Feb 2020 10:35:27 +0800 From: Can Guo To: Stanley Chu Cc: linux-scsi@vger.kernel.org, martin.petersen@oracle.com, avri.altman@wdc.com, alim.akhtar@samsung.com, jejb@linux.ibm.com, beanhuo@micron.com, asutoshd@codeaurora.org, matthias.bgg@gmail.com, bvanassche@acm.org, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kuohong.wang@mediatek.com, peter.wang@mediatek.com, chun-hung.wu@mediatek.com, andy.teng@mediatek.com Subject: Re: [PATCH v1 1/2] scsi: ufs: add required delay after gating reference clock In-Reply-To: <56c1fc80919491d058d904fcc7301835@codeaurora.org> References: <20200217093559.16830-1-stanley.chu@mediatek.com> <20200217093559.16830-2-stanley.chu@mediatek.com> <1581945168.26304.4.camel@mtksdccf07> <1581946449.26304.15.camel@mtksdccf07> <56c1fc80919491d058d904fcc7301835@codeaurora.org> Message-ID: X-Sender: cang@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Stanely, On 2020-02-17 21:42, Can Guo wrote: > On 2020-02-17 21:34, Stanley Chu wrote: >> Hi Can, >> >> On Mon, 2020-02-17 at 21:22 +0800, Can Guo wrote: >>> On 2020-02-17 21:12, Stanley Chu wrote: >>> > Hi Can, >>> > >>> > >>> >> > } else if (!on && clki->enabled) { >>> >> > clk_disable_unprepare(clki->clk); >>> >> > + wait_us = hba->dev_info.clk_gating_wait_us; >>> >> > + if (ref_clk && wait_us) >>> >> > + usleep_range(wait_us, wait_us + 10); >>> >> >>> >> Hi St,anley, >>> >> >>> >> If wait_us is 1us, it would be inappropriate to use usleep_range() >>> >> here. >>> >> You have checks of the delay in patch #2, but why it is not needed >>> >> here? >>> >> >>> >> Thanks, >>> >> Can Guo. >>> > >>> > You are right. I could make that delay checking as common function so >>> > it >>> > can be used here as well to cover all possible values. >>> > >>> > Thanks for suggestion. >>> > Stanley >>> >>> Hi Stanley, >>> >>> One more thing, as in patch #2, you have already added delays in your >>> ufshcd_vops_setup_clocks(OFF, PRE_CHANGE) path, plus this delay here, >>> don't you delay for 2*bRefClkGatingWaitTime in ufshcd_setup_clocks()? >>> As the delay added in your vops also delays the actions of turning >>> off all the other clocks in ufshcd_setup_clocks(), you don't need the >>> delay here again, do you agree? >> >> MediaTek driver is not using reference clocks named as "ref_clk" >> defined >> in device tree, thus the delay specific for "ref_clk" in >> ufshcd_setup_clocks() will not be applied in MediaTek platform. >> >> This patch is aimed to add delay for this kind of "ref_clk" used by >> any >> future vendors. >> >> Anyway thanks for the reminding : ) >> >>> >>> Thanks, >>> Can Guo. >> >> >> Thanks, >> Stanley > > Hi Stanley, > > Then we are unluckily hit by this change. We have ref_clk in DT, thus > this change would add unwanted delays to our platforms. but still we > disable device's ref_clk in vops. :) > > Could you please hold on patch #1 first? I need sometime to have a > dicussion with my colleagues on this. > > Thanks. > Can Guo. Since we all need this delay here, how about put the delay in the entrence of ufshcd_setup_clocks(), before vops_setup_clocks()? If so, we can remove all the delays we added in our vops since the delay anyways delays everything inside ufshcd_setup_clocks(). Meanwhile, if you want to modify the delay (hba->dev_info.clk_gating_wait_us) for some reasons, say for specific UFS devices, you still can do it in vops_apply_dev_quirks(). What do you say? Thanks, Can Guo.