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=-6.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 CE6DDC35247 for ; Fri, 7 Feb 2020 01:09:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A331F20658 for ; Fri, 7 Feb 2020 01:09:44 +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="QIsHaDGk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727178AbgBGBJo (ORCPT ); Thu, 6 Feb 2020 20:09:44 -0500 Received: from mail26.static.mailgun.info ([104.130.122.26]:14299 "EHLO mail26.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726810AbgBGBJn (ORCPT ); Thu, 6 Feb 2020 20:09:43 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1581037782; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=xylf21tQ/JOS5H4BtABwYa4jpJVYq9qvknGFCyM7akU=; b=QIsHaDGkbWTc+k/E28S4sksGqQdzElzcCxpcj60UcIHZmyW0TP9KGD94YvhklXXhC/m3dvru +6gMgZNOgoFrxUX3AcTvJuEGv/CwO459l2SIVbBp8kRX10srbZm7vwUnMasn8DC+8cXkCCFX 7iUAwe3Fok+3V8RbnxOMapih5Zo= X-Mailgun-Sending-Ip: 104.130.122.26 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 5e3cb8d2.7fc8407b2ab0-smtp-out-n03; Fri, 07 Feb 2020 01:09:38 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 1CA3DC447A1; Fri, 7 Feb 2020 01:09:37 +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 337AAC43383; Fri, 7 Feb 2020 01:09:36 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Fri, 07 Feb 2020 09:09:36 +0800 From: Can Guo To: Bjorn Andersson Cc: asutoshd@codeaurora.org, nguyenb@codeaurora.org, hongwus@codeaurora.org, rnayak@codeaurora.org, linux-scsi@vger.kernel.org, kernel-team@android.com, saravanak@google.com, salyzyn@google.com, Andy Gross , Alim Akhtar , Avri Altman , "James E.J. Bottomley" , "Martin K. Petersen" , "open list:ARM/QUALCOMM SUPPORT" , open list Subject: Re: [PATCH v7 7/8] scsi: ufs-qcom: Delay specific time before gate ref clk In-Reply-To: <20200206203336.GQ2514@yoga> References: <1580978008-9327-1-git-send-email-cang@codeaurora.org> <1580978008-9327-8-git-send-email-cang@codeaurora.org> <20200206203336.GQ2514@yoga> Message-ID: <9de3632cf0c65347684b8c5f4f3c63b3@codeaurora.org> 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 On 2020-02-07 04:33, Bjorn Andersson wrote: > On Thu 06 Feb 00:33 PST 2020, Can Guo wrote: > >> After enter hibern8, as UFS JEDEC ver 3.0 requires, a specific gating >> wait >> time is required before disable the device reference clock. If it is >> not >> specified, use the old delay. >> >> Signed-off-by: Can Guo >> Reviewed-by: Asutosh Das >> Reviewed-by: Hongwu Su >> --- >> drivers/scsi/ufs/ufs-qcom.c | 22 +++++++++++++++++++--- >> 1 file changed, 19 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c >> index 85d7c17..39eefa4 100644 >> --- a/drivers/scsi/ufs/ufs-qcom.c >> +++ b/drivers/scsi/ufs/ufs-qcom.c >> @@ -833,6 +833,8 @@ static int ufs_qcom_bus_register(struct >> ufs_qcom_host *host) >> >> static void ufs_qcom_dev_ref_clk_ctrl(struct ufs_qcom_host *host, >> bool enable) >> { >> + unsigned long gating_wait; >> + >> if (host->dev_ref_clk_ctrl_mmio && >> (enable ^ host->is_dev_ref_clk_enabled)) { >> u32 temp = readl_relaxed(host->dev_ref_clk_ctrl_mmio); >> @@ -845,11 +847,25 @@ static void ufs_qcom_dev_ref_clk_ctrl(struct >> ufs_qcom_host *host, bool enable) >> /* >> * If we are here to disable this clock it might be immediately >> * after entering into hibern8 in which case we need to make >> - * sure that device ref_clk is active at least 1us after the >> + * sure that device ref_clk is active for specific time after >> * hibern8 enter. >> */ >> - if (!enable) >> - udelay(1); >> + if (!enable) { >> + gating_wait = host->hba->dev_info.clk_gating_wait_us; >> + if (!gating_wait) { > > Afaict this can't happen, because in patch 6 you check for gating_wait > being 0 and if so set it to 0xff. > Sorry, I was intended to give clk_gating_wait_us values only if it is a UFS3.0 device. I will revise patch 6/8. >> + udelay(1); >> + } else { >> + /* >> + * bRefClkGatingWaitTime defines the minimum >> + * time for which the reference clock is >> + * required by device during transition from >> + * HS-MODE to LS-MODE or HIBERN8 state. Give it >> + * more time to be on the safe side. >> + */ >> + gating_wait += 10; >> + usleep_range(gating_wait, gating_wait + 10); > > I presume there's no strong requirement on the max, so how about using > a > substantially larger max - say 1k, or 10k - to allow the usleep_range() > to do it's job? > > > PS. Please include linux-arm-msm@ on all the patches in the series, not > just two of them. > > Regards, > Bjorn > bRefClkGatingWaitTime, as vendor defined in their device attribute is usually around 50~100, 1k or 10k delay makes it too large. usleep_range() works well so long as the delay is within (10us - 20ms), so I added 10 to make sure it is above 10us. SLEEPING FOR ~USECS OR SMALL MSECS ( 10us - 20ms): * Use usleep_range https://www.kernel.org/doc/Documentation/timers/timers-howto.txt Thanks, Can Guo. >> + } >> + } >> >> writel_relaxed(temp, host->dev_ref_clk_ctrl_mmio); >> >> -- >> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora >> Forum, >> a Linux Foundation Collaborative Project