From nobody Fri Dec 19 17:00:39 2025 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 40145745E5 for ; Thu, 21 Dec 2023 18:25:45 +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 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="P5Ybnato" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1703183145; 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=4219KYM+Lx5MIoMXHlnouIE3ETSXouTN4mLohiWEzAY=; b=P5YbnatoUxoLz4x7kVjciDdmYJ8ITPdPbFDScXogbYznJ91mXVx7pUA/ILfdK75y362Kh5 vOAAHDj8BzPn/XATDZ1gTZoPxgqSnrcxf25/3tTeblrluDP18sSCR8HxF1bnRjljpcLFJ+ E5evAgJW0DU1/wXBwAnAVwUVCbX7iqQ= 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-586-R-_pKPRdOxKn_eJaM98ueg-1; Thu, 21 Dec 2023 13:25:43 -0500 X-MC-Unique: R-_pKPRdOxKn_eJaM98ueg-1 Received: by mail-qv1-f71.google.com with SMTP id 6a1803df08f44-67eee3fbeb1so16441736d6.2 for ; Thu, 21 Dec 2023 10:25:43 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703183140; x=1703787940; 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=4219KYM+Lx5MIoMXHlnouIE3ETSXouTN4mLohiWEzAY=; b=Bn1MSO5yIEe0XVf4jkOeUesagzmsMlCdKXy7uh/eFoSWmrcnnslWTAjcWdqpABb9xV eR8CTDsznr5PNN8tWSrZ8eZzYyJ9GR5o883KrfTiOiuClrbh2URl/DZFm5+4prS/xkj5 zxpSE3o9wH92gGJTuhqNQxY2oS0m85A3syAWPxWCT08arVZzl595rpRlDJ00qA3mp9ii H8+1451Y9V8iChDszba4k6w+WJHY+kfJ3tvg3njX0KTrAD9GXcOoSnRn/khKS1UICkhL idC/tkVjOe/VW3BX50Q4I3u+zZ9cYw0iMthHSyx6KL3IDa10wPYVRrRc57gHrgDknbX0 gb6g== X-Gm-Message-State: AOJu0YyCQZWt9FBrUjXJqdTzzaSC2wp+iJ/EmXxL+s5dsi9UsoqgDPtw b6PwuEHImKjrfnNcR2hlCKettlkpZZmTIGquPBdYEy0hzZkLvG2iF3QHMrBOcR1EWNVl7GDJ5Fu btDEbvTVYJ0W+9p6o59XJMg2lBoq8ZaaF X-Received: by 2002:a05:6214:c69:b0:67f:2167:add8 with SMTP id t9-20020a0562140c6900b0067f2167add8mr128954qvj.63.1703183139772; Thu, 21 Dec 2023 10:25:39 -0800 (PST) X-Google-Smtp-Source: AGHT+IEZ5Ey0k8eka1Tmd1wHccFHcVx5O7AMpaYlZVPVIE4Mlzs93Ul5Aid/9sPv0OnMJmxA3rI2gQ== X-Received: by 2002:a05:6214:c69:b0:67f:2167:add8 with SMTP id t9-20020a0562140c6900b0067f2167add8mr128935qvj.63.1703183139516; Thu, 21 Dec 2023 10:25:39 -0800 (PST) Received: from [192.168.1.163] ([2600:1700:1ff0:d0e0::37]) by smtp.gmail.com with ESMTPSA id da7-20020a05621408c700b0067f2c03d4adsm779605qvb.100.2023.12.21.10.25.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Dec 2023 10:25:37 -0800 (PST) From: Andrew Halaney Date: Thu, 21 Dec 2023 12:25:21 -0600 Subject: [PATCH RFC v2 04/11] scsi: ufs: qcom: Perform read back after writing unipro mode Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20231221-ufs-reset-ensure-effect-before-delay-v2-4-75af2a9bae51@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 , Bjorn Andersson , Konrad Dybcio , Manivannan Sadhasivam , "James E.J. Bottomley" , "Martin K. Petersen" , Yaniv Gardi , Dov Levenglick , Hannes Reinecke , Subhash Jadavani , Gilad Broner , Venkat Gopalakrishnan , Janek Kotas , Alim Akhtar , Avri Altman , Bart Van Assche , Anjana Hari , Dolev Raviv , Can Guo Cc: Will Deacon , linux-arm-msm@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Halaney X-Mailer: b4 0.12.3 Currently, the QUNIPRO_SEL bit is written to and then an mb() is used to ensure that completes before continuing. 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=3DMiyxB5cKJXSaoc01&t=3D1678 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 powe= r optimizations") Signed-off-by: Andrew Halaney --- 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 6df2ab3b6f23..ab1ff7432d11 100644 --- a/drivers/ufs/host/ufs-qcom.c +++ b/drivers/ufs/host/ufs-qcom.c @@ -280,7 +280,7 @@ static void ufs_qcom_select_unipro_mode(struct ufs_qcom= _host *host) ufshcd_rmwl(host->hba, QUNIPRO_G4_SEL, 0, REG_UFS_CFG0); =20 /* make sure above configuration is applied before we return */ - mb(); + ufshcd_readl(host->hba, REG_UFS_CFG1); } =20 /* --=20 2.43.0