From patchwork Thu Dec 21 18:25:20 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Halaney X-Patchwork-Id: 13502524 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 8DA9465184 for ; Thu, 21 Dec 2023 18:25:39 +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="QYAhkS7N" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1703183138; 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=n1l5xZhbao6yyLMAHMlDGMBOyE+StA4U3ea1c7HAYjQ=; b=QYAhkS7NaxaAtt3UzdI80oINkSHoaFMJYgNk1bvUSAek2zISUc4CEcfGJwo3NKmBGL0gzl ywwBtWtyHreZFEpqS2I+sxgUIuA5cf+Rzjw4Dnz4N+QRyoJLK8HkRjF320voXF6FhyNYY8 /91s9PsY6v8/mRDblG9HNlNsgfyFKgs= 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-681-rWcXwPO1PUGFikw0v9k16Q-1; Thu, 21 Dec 2023 13:25:36 -0500 X-MC-Unique: rWcXwPO1PUGFikw0v9k16Q-1 Received: by mail-qv1-f71.google.com with SMTP id 6a1803df08f44-67f772d30a9so14601896d6.0 for ; Thu, 21 Dec 2023 10:25:36 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703183136; x=1703787936; 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=n1l5xZhbao6yyLMAHMlDGMBOyE+StA4U3ea1c7HAYjQ=; b=ayy1PUYBqXkIOO+U/IbcagJri/WwFfLBCw9q5iOswLhXU2EjpFp5SA5PFyvVj3V7ag bltWFbhkoUcg3z86f4j4NDDFWV7oMkB7BhFpyk2LK4Eot6BUJtqO3D0vz6QItLsMJrQz ILg90Fe1E4b0Z20J0auFwsWpUpr/md+1dH6zKOrEoOEjKFuq1vYiih+6HADZhn6w3c7p m/4+EII1FfUFZ2C8qC5YZq3jgdUpKi0z87otYtIoBegAESv2T7/LXrSYOSVuwQ5D0Gnv CW6CDFKbx2DvxR2tKF1nRtESJ5X1xN166WP5drbRaCdK5Q6ocK4s/oom85rv3fHjvFdH 1v2A== X-Gm-Message-State: AOJu0YxpzJSASQgJuIbgz50KTH5LyvdYkU5ZGyGTjQsuvs9UCnbXAMic T9OFFV6sbsnHZwvul8Jx4xLvix287+V23Tq3er4Jl/WU5AaDfscOE8ZKfClumaZlHNc4oqcmFvj UhxtZywc9jxrYqOEftlQwh3Nhl6zt4A== X-Received: by 2002:a05:6214:d64:b0:67f:8030:11b6 with SMTP id 4-20020a0562140d6400b0067f803011b6mr143701qvs.1.1703183136390; Thu, 21 Dec 2023 10:25:36 -0800 (PST) X-Google-Smtp-Source: AGHT+IEAzXrN6xp5NXvGmNMODFPQUjQ7aDI/PGRXenVrRKBESBkOuIGn70QZyjUSa4x9/Ih3wgVgcg== X-Received: by 2002:a05:6214:d64:b0:67f:8030:11b6 with SMTP id 4-20020a0562140d6400b0067f803011b6mr143691qvs.1.1703183136181; Thu, 21 Dec 2023 10:25:36 -0800 (PST) Received: from [192.168.1.163] ([2600:1700:1ff0:d0e0::37]) by smtp.gmail.com with ESMTPSA id da7-20020a05621408c700b0067f2c03d4adsm779605qvb.100.2023.12.21.10.25.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Dec 2023 10:25:35 -0800 (PST) From: Andrew Halaney Date: Thu, 21 Dec 2023 12:25:20 -0600 Subject: [PATCH RFC v2 03/11] scsi: ufs: qcom: Perform read back after writing testbus config Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20231221-ufs-reset-ensure-effect-before-delay-v2-3-75af2a9bae51@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 testbus configuration is written and completed with an mb(). 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: 9c46b8676271 ("scsi: ufs-qcom: dump additional testbus registers") Signed-off-by: Andrew Halaney --- drivers/ufs/host/ufs-qcom.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c index 4c15c8a1d058..6df2ab3b6f23 100644 --- a/drivers/ufs/host/ufs-qcom.c +++ b/drivers/ufs/host/ufs-qcom.c @@ -1332,6 +1332,9 @@ static void ufs_qcom_enable_test_bus(struct ufs_qcom_host *host) ufshcd_rmwl(host->hba, UFS_REG_TEST_BUS_EN, UFS_REG_TEST_BUS_EN, REG_UFS_CFG1); ufshcd_rmwl(host->hba, TEST_BUS_EN, TEST_BUS_EN, REG_UFS_CFG1); + + /* dummy read to ensure this has been enabled prior to returning */ + ufshcd_readl(host->hba, REG_UFS_CFG1); } static void ufs_qcom_get_default_testbus_cfg(struct ufs_qcom_host *host) @@ -1429,11 +1432,6 @@ int ufs_qcom_testbus_config(struct ufs_qcom_host *host) (u32)host->testbus.select_minor << offset, reg); ufs_qcom_enable_test_bus(host); - /* - * Make sure the test bus configuration is - * committed before returning. - */ - mb(); return 0; }