From patchwork Thu Dec 21 18:25:21 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Halaney X-Patchwork-Id: 13502516 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 08C5073185 for ; Thu, 21 Dec 2023 18:25:42 +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="AfoqYHMx" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1703183142; 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=AfoqYHMxqZO+qhO2k2mD2kZAIKj5YiD8xGMEpJoZvp0pHViS4bShwAOHyx3Yx7oqZJZJQV xkNYmB2TZEkl7JFmXxuktW/Rt6Km/Sy+sCkwZzOOFOLYoqIKL71rbFec/f01OTODSVjLiv ElK7QeQxm2AnjzAcei4CqgxXRDtdOEs= Received: from mail-qv1-f70.google.com (mail-qv1-f70.google.com [209.85.219.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-362-JLPpFBZLOQ2_EnqAx04TJg-1; Thu, 21 Dec 2023 13:25:40 -0500 X-MC-Unique: JLPpFBZLOQ2_EnqAx04TJg-1 Received: by mail-qv1-f70.google.com with SMTP id 6a1803df08f44-67ef8bbfe89so16627386d6.0 for ; Thu, 21 Dec 2023 10:25:40 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703183139; x=1703787939; 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=SK/KGks9FW3izxh6A6UVnbb9amWLkY/jXUSblTwJD80KX1pmsuSnFYEUxJnyiYuLj7 kzoJWdOYhggPghPyHd4hRWN7dAAlBq/vaser0jogFOHErjQomdRZJsqsTJtzi/u+Kvy7 /gu1bVIDZZkimUZUMyZG61YffKM50oziuZVDWFQY71l2n9f4ixniwHvfOw66ir966iMC ZGH727LDtI7zEthbqUEiG6v9CEvsq9SGF4xQacTA+ZiA17VEbJ3OOlJZvPP/lDo9mv7Q 0anz73GIfJkXHQKy1J7ufkS4Yq2yLwgbWsZcRQEhG38+5X103Jl+l7miJXzsAOWCKaKT xs3w== X-Gm-Message-State: AOJu0YzpBY035+upIfBhRNanhY2EGiNgaEHCFpMPllwZ5+wZo/Q0X5Gx vt9ycRu6/7yadtPb8GaukhccXVzwqsFGWHLv/WBD4K4+c+XlAZb0FE5iSQVzfND1rSMybnWz3ln nwBajpBl+iLog3S/D8dopk4eWM6yLFMJgVw== X-Received: by 2002:a05:6214:c69:b0:67f:2167:add8 with SMTP id t9-20020a0562140c6900b0067f2167add8mr128949qvj.63.1703183139769; 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-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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=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 --- 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); /* make sure above configuration is applied before we return */ - mb(); + ufshcd_readl(host->hba, REG_UFS_CFG1); } /*