[RFC,v2,02/11] scsi: ufs: qcom: Perform read back after writing REG_UFS_SYS1CLK_1US
Message ID | 20231221-ufs-reset-ensure-effect-before-delay-v2-2-75af2a9bae51@redhat.com |
---|---|
State | New |
Headers |
Return-Path: <linux-kernel+bounces-8914-ouuuleilei=gmail.com@vger.kernel.org> Delivered-To: ouuuleilei@gmail.com Received: by 2002:a05:7300:2483:b0:fb:cd0c:d3e with SMTP id q3csp605569dyi; Thu, 21 Dec 2023 10:26:34 -0800 (PST) X-Google-Smtp-Source: AGHT+IFTdOrXIkz9/fIfzH9MCGjb4h1hbBg9rHBsycMs55+6iLubclaYEl+yO52W+hwxTaUH1W/D X-Received: by 2002:a17:907:9727:b0:a22:fb3f:7a67 with SMTP id jg39-20020a170907972700b00a22fb3f7a67mr144686ejc.150.1703183194527; Thu, 21 Dec 2023 10:26:34 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1703183194; cv=none; d=google.com; s=arc-20160816; b=x0eArmIKxB699P/Jb7TF63VgoioTF6qlUvAt3PI/X2EXGsiiYiDgSZ7Eki1k7DCw6p eJXAfYN+hnu35EfIrezkfA6WQIZG01fXqmRej32Apc3OX2OHojY1PyR6UXHIVpWmWyjT i9fG83pspXJt8mL0gn+sDrI+zm5FcLEcolhHL2zg5Odv0mULh2FwHN03d8Dgxg1/6yNq dJwAdxuT2hde5zjKLZUGQuoGEyAJx0uYQAL6LlK5reif3BPBuIF3uGiR4xwOD8GfcGh1 xi8l4z/qMv/QgeRMyZ2mZt0h1L/jkiWAKGFGRf+Wya2ePCbxlL8BCX7+AqHMIujoI/6J FgsA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:list-unsubscribe:list-subscribe:list-id:precedence :subject:date:from:dkim-signature; bh=V5DIcTT5Lroakb0MY1T0EdVJKAtxjaPCe5FVxbyPj6I=; fh=04D4Yk3yOxJShnjvHS+/hsfQo1XzUk2+baHXEOLZllI=; b=0uovVsDK8ldTSig8xtNtfEpfP7MMWSrASQjcjYYKP9M24pm5KfmTkjHzHr2SXzYT6H clKl2xg7xTGAkotvXgMUg9zo3AzBmLQzKi92kGtES+VceKkCZXoEsIEU2N6E5BKOa5cx 3rRZ9hlCtKZJnD9ugmTXjpvOGO3fcKOLetObH27GKSjQITppKNt5OraLdl/gaI0simzh LGjF/DOghw4xtzXCwk8p2qjABBrgOJq1xFjwwty/dLsKD6EhNlB0CJ7w+J8SV9wE6eHG mfhYE/O0Y2AaBjfqNsSqFovZtyzxdSSqVSdfZCvgwjCbpvAJVAWbPAqkt1Cz8oawSCS0 JZ+g== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=UoTwTWS0; spf=pass (google.com: domain of linux-kernel+bounces-8914-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) smtp.mailfrom="linux-kernel+bounces-8914-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from am.mirrors.kernel.org (am.mirrors.kernel.org. [2604:1380:4601:e00::3]) by mx.google.com with ESMTPS id k26-20020a17090666da00b00a26ac4006ffsi459833ejp.186.2023.12.21.10.26.34 for <ouuuleilei@gmail.com> (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Dec 2023 10:26:34 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-8914-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=UoTwTWS0; spf=pass (google.com: domain of linux-kernel+bounces-8914-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) smtp.mailfrom="linux-kernel+bounces-8914-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by am.mirrors.kernel.org (Postfix) with ESMTPS id ED6DE1F22176 for <ouuuleilei@gmail.com>; Thu, 21 Dec 2023 18:26:33 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A154B651BC; Thu, 21 Dec 2023 18:25:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="UoTwTWS0" X-Original-To: linux-kernel@vger.kernel.org Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A23F76350E for <linux-kernel@vger.kernel.org>; Thu, 21 Dec 2023 18:25:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1703183136; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=V5DIcTT5Lroakb0MY1T0EdVJKAtxjaPCe5FVxbyPj6I=; b=UoTwTWS0lbXAG1PtFStjACVNiIz1QJWR7kWXLqmFXO6+3bYFPVjFJSuOkMyj4VV5MnWXyt gUa/ll/VA7zqgFC3mZP5s09FVts5s+sSv73/NLk+hB7kUT/AwG+1rR1FjlnNKlErYRafhb Vrk6FvZNwDfK72kCMoES3Tdocwy5YOw= Received: from mail-qv1-f71.google.com (mail-qv1-f71.google.com [209.85.219.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-76-0IWSGrvdM5WWjKSdCq5o8Q-1; Thu, 21 Dec 2023 13:25:35 -0500 X-MC-Unique: 0IWSGrvdM5WWjKSdCq5o8Q-1 Received: by mail-qv1-f71.google.com with SMTP id 6a1803df08f44-67ef8bbfe89so16626556d6.0 for <linux-kernel@vger.kernel.org>; Thu, 21 Dec 2023 10:25:35 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703183135; x=1703787935; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=V5DIcTT5Lroakb0MY1T0EdVJKAtxjaPCe5FVxbyPj6I=; b=EvMPAbVtD+VcOpMvtX8lDQpSqOppa5XVaYVkD7B3xA3SxdwGZcrSTlVv7A8Sd+qt85 Di282smpiJpDY5YizwhZePXVbTa3c7uc1xEjv0xnxGOasTQ2UGZ7gjpEQ2rq8eA+s7WA FqOmawaStaYD8h2GpdPES2UHaJV1uNChDrgiULS8BOiWLFN9V9szad0sNQ0xsLNb+l8d Peod2D+qBvTMa67FWclX3vTk+1qBOzmCiFlrZcJweZrqVdCr+XRZ+hJLNpH6GGvJqp9r lzIJIagbSadb92Nx39Skot6gFa08EGxh/PiZR5/B013yVk3LGFwkcIdZ2v9NPPHmB4XO fckQ== X-Gm-Message-State: AOJu0Yzt1FtCHtesaJiisDxbQj2jKw2KXXwmaHPdWEzC47OS8DO1tLqn TKYSzfj+SNxBCLF0oH46fy0YtIbpqk/nPdVPwo+z5BR8c3AkQAj9v7BJCRs/nFbjjuGMvmZSqXO Laj7u4rFsZoibJKGBwH4eBp2UP3aG8fP6 X-Received: by 2002:a05:6214:1948:b0:67c:d2fd:3e3f with SMTP id q8-20020a056214194800b0067cd2fd3e3fmr172132qvk.27.1703183134902; Thu, 21 Dec 2023 10:25:34 -0800 (PST) X-Received: by 2002:a05:6214:1948:b0:67c:d2fd:3e3f with SMTP id q8-20020a056214194800b0067cd2fd3e3fmr172113qvk.27.1703183134657; Thu, 21 Dec 2023 10:25:34 -0800 (PST) Received: from [192.168.1.163] ([2600:1700:1ff0:d0e0::37]) by smtp.gmail.com with ESMTPSA id da7-20020a05621408c700b0067f2c03d4adsm779605qvb.100.2023.12.21.10.25.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Dec 2023 10:25:30 -0800 (PST) From: Andrew Halaney <ahalaney@redhat.com> Date: Thu, 21 Dec 2023 12:25:19 -0600 Subject: [PATCH RFC v2 02/11] scsi: ufs: qcom: Perform read back after writing REG_UFS_SYS1CLK_1US Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: <linux-kernel.vger.kernel.org> List-Subscribe: <mailto:linux-kernel+subscribe@vger.kernel.org> List-Unsubscribe: <mailto:linux-kernel+unsubscribe@vger.kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20231221-ufs-reset-ensure-effect-before-delay-v2-2-75af2a9bae51@redhat.com> References: <20231221-ufs-reset-ensure-effect-before-delay-v2-0-75af2a9bae51@redhat.com> In-Reply-To: <20231221-ufs-reset-ensure-effect-before-delay-v2-0-75af2a9bae51@redhat.com> To: Andy Gross <agross@kernel.org>, Bjorn Andersson <andersson@kernel.org>, Konrad Dybcio <konrad.dybcio@linaro.org>, Manivannan Sadhasivam <mani@kernel.org>, "James E.J. Bottomley" <jejb@linux.ibm.com>, "Martin K. Petersen" <martin.petersen@oracle.com>, Yaniv Gardi <ygardi@codeaurora.org>, Dov Levenglick <dovl@codeaurora.org>, Hannes Reinecke <hare@suse.de>, Subhash Jadavani <subhashj@codeaurora.org>, Gilad Broner <gbroner@codeaurora.org>, Venkat Gopalakrishnan <venkatg@codeaurora.org>, Janek Kotas <jank@cadence.com>, Alim Akhtar <alim.akhtar@samsung.com>, Avri Altman <avri.altman@wdc.com>, Bart Van Assche <bvanassche@acm.org>, Anjana Hari <quic_ahari@quicinc.com>, Dolev Raviv <draviv@codeaurora.org>, Can Guo <quic_cang@quicinc.com> Cc: Will Deacon <will@kernel.org>, linux-arm-msm@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Halaney <ahalaney@redhat.com> X-Mailer: b4 0.12.3 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1785917021455703531 X-GMAIL-MSGID: 1785917021455703531 |
Series |
scsi: ufs: Remove overzealous memory barriers
|
|
Commit Message
Andrew Halaney
Dec. 21, 2023, 6:25 p.m. UTC
Currently after writing to REG_UFS_SYS1CLK_1US a mb() is used to ensure
that write has gone through to the device.
mb() ensure that the write completes, but completion doesn't mean that
it isn't stored in a buffer somewhere. The recommendation for
ensuring this bit has taken effect on the device is to perform a read
back to force it to make it all the way to the device. This is
documented in device-io.rst and a talk by Will Deacon on this can
be seen over here:
https://youtu.be/i6DayghhA8Q?si=MiyxB5cKJXSaoc01&t=1678
Let's do that to ensure the bit hits the device. Because the mb()'s
purpose wasn't to add extra ordering (on top of the ordering guaranteed
by writel()/readl()), it can safely be removed.
Fixes: f06fcc7155dc ("scsi: ufs-qcom: add QUniPro hardware support and power optimizations")
Signed-off-by: Andrew Halaney <ahalaney@redhat.com>
---
drivers/ufs/host/ufs-qcom.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c index 480787048e75..4c15c8a1d058 100644 --- a/drivers/ufs/host/ufs-qcom.c +++ b/drivers/ufs/host/ufs-qcom.c @@ -501,7 +501,7 @@ static int ufs_qcom_cfg_timers(struct ufs_hba *hba, u32 gear, * make sure above write gets applied before we return from * this function. */ - mb(); + ufshcd_readl(hba, REG_UFS_SYS1CLK_1US); } return 0;