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: 757113 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 98B0564AB9 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-f69.google.com (mail-qv1-f69.google.com [209.85.219.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-546-sb0_1an5O9mgs4w2rOWOTQ-1; Thu, 21 Dec 2023 13:25:36 -0500 X-MC-Unique: sb0_1an5O9mgs4w2rOWOTQ-1 Received: by mail-qv1-f69.google.com with SMTP id 6a1803df08f44-67f7748ad02so14431216d6.1 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=TztcnCpKqqMNwmg20r7NwbcRilyQHqqVEM37XOsdbGMnf03oXJ7TfIcuqhyxs+3/dO sE8Ilen4hZvHfYVCZCwusF9iHRodeRj3PfI/qoFLX6mHmRjZw3onNtM0/rW/VUPQ/HCR GU1pzwNEluP8KypxpM1BLucVVsueriUsDl0qwQQ+k0EhscdjOAZlRFVl9gAqJdFBVLjL 1lIAKQBjQ2iMvOg6Zlt9GjVOVrV6g7l1qcpgpMTRf3BGSbibw6hZcH+Hc63gGyyJDS1F 4dAAHD55xYCR/8z3pXjhTmWUmzcIDyRik8Mwb7IZEPkxzzkVKA3A+GrfT7iFLsd2MWPt grrw== X-Gm-Message-State: AOJu0YyP3SS0lXRF29IzlVa0GKZrlR7EswbTrNFcNhWu0QQZ9xwWLw0/ 7l0hLIoho+jk8dj0i/66Ads9a/PTjKQix73ehhq8LKbj5gD7xjS9L7E3EzG0cAPdnzXBrbu/zVP NY0FI5v1XVy6jjPgrbQUQ21xycxT1RWUBHg== X-Received: by 2002:a05:6214:d64:b0:67f:8030:11b6 with SMTP id 4-20020a0562140d6400b0067f803011b6mr143696qvs.1.1703183136386; 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-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20231221-ufs-reset-ensure-effect-before-delay-v2-3-75af2a9bae51@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; }