From patchwork Thu Dec 21 19:09:57 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Halaney X-Patchwork-Id: 13502583 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 AB8F078E8C for ; Thu, 21 Dec 2023 19:11:26 +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="iv0nbZfy" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1703185885; 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=4cSBdvbxI8LSVPr25rTyKCoUJu91IkN+EuBnNL3WBh0=; b=iv0nbZfy0ZEieAaEjrSPFPvS69EvGrq62HUFasTVSSAxIMie6FzowdeouvcalG3gfdUJ4k XTaDb7hyoKnbidxHy458qMr88OtQSPapdjyRkepDpM4srcqD+BvKMplOEb+S7XnwvQs1P5 QdDoxbi3o+rzqZEr1JEDhsp2fvI748o= 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-185-IMeaVg03Pgm3eeJINcjklg-1; Thu, 21 Dec 2023 14:11:23 -0500 X-MC-Unique: IMeaVg03Pgm3eeJINcjklg-1 Received: by mail-qv1-f71.google.com with SMTP id 6a1803df08f44-67f6f90587aso15247396d6.3 for ; Thu, 21 Dec 2023 11:11:23 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703185881; x=1703790681; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=4cSBdvbxI8LSVPr25rTyKCoUJu91IkN+EuBnNL3WBh0=; b=Y1Fg9bK4rydmQTFGMeh/bb4/MgvTygVlRR3wEuGStkdufxtLaWAH3Qwydk4wsvjEIA KdkyjFN6UotcZExZGVRH+M8/vr+KXfJdMM/gBYLvSsbbqE4pAoUY7CO7ps6dXu8fvA6f gViGyoiN04GBIU2ppKQ1Qk30YyLsm0diN2YaqEtW0Cp9eH3HcSorSmEE7SqIYb1p/Coz kxNYr70Aif0G2g084xw3BPfQgekhDtNaloplLCynQfcxwBEu6MX/fwwvKBMvKDKzhOdd 7qJEYl2RQjTmXtLLoJtIUpsJa0QEWIrqbjw0PdOxSjKBLypZxIiJCLg7UtWmyCMNOuUg YMNA== X-Gm-Message-State: AOJu0YyrgaQyGLPH/bsm6jqnkuoBfedo0frTaW1lm+e86TdnvHFFZKYE fgIuyFUGYJiXM01ohD+DesYMbbyfMfRhw2n4ClygewofRhtyyeNN+4c0AMptNSKTG5Ax07IqcSl gqQfN0BDbiy/MTtrE1M74N0pxeANcpjMc2qJKhQ== X-Received: by 2002:ad4:5e8c:0:b0:67f:2201:81e1 with SMTP id jl12-20020ad45e8c000000b0067f220181e1mr222526qvb.13.1703185881311; Thu, 21 Dec 2023 11:11:21 -0800 (PST) X-Google-Smtp-Source: AGHT+IGf7+G9N49GFMXR/htbqQ1Lb5/TJZIyMXTWcnIiiUlAQ5o6qGsg7peSQ1lv4VxWTuFlkzHUAg== X-Received: by 2002:ad4:5e8c:0:b0:67f:2201:81e1 with SMTP id jl12-20020ad45e8c000000b0067f220181e1mr222500qvb.13.1703185881066; Thu, 21 Dec 2023 11:11:21 -0800 (PST) Received: from fedora.redhat.com ([2600:1700:1ff0:d0e0::37]) by smtp.gmail.com with ESMTPSA id 25-20020a05620a04d900b0077f0a4bd3c6sm846370qks.77.2023.12.21.11.11.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Dec 2023 11:11:19 -0800 (PST) From: Andrew Halaney To: Andy Gross , Bjorn Andersson , Konrad Dybcio , Manivannan Sadhasivam , "James E.J. Bottomley" , "Martin K. Petersen" , Hannes Reinecke , Janek Kotas , Alim Akhtar , Avri Altman , Bart Van Assche , Can Guo Cc: Andrew Halaney , Will Deacon , linux-arm-msm@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH RFC v3 11/11] scsi: ufs: core: Perform read back before writing run/stop regs Date: Thu, 21 Dec 2023 13:09:57 -0600 Message-ID: <20231221-ufs-reset-ensure-effect-before-delay-v3-11-2195a1b66d2e@redhat.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231221-ufs-reset-ensure-effect-before-delay-v3-0-2195a1b66d2e@redhat.com> References: <20231221-ufs-reset-ensure-effect-before-delay-v3-0-2195a1b66d2e@redhat.com> Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Mailer: b4 0.12.3 Currently a wmb() is used to ensure that writes to the UTP_TASK_REQ_LIST_BASE* regs are completed prior to following writes to the run/stop registers. wmb() ensure that the write completes, but completion doesn't mean that it isn't stored in a buffer somewhere. The recommendation for ensuring the bits have 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 bits hit the device. Because the wmb()'s purpose wasn't to add extra ordering (on top of the ordering guaranteed by writel()/readl()), it can safely be removed. Fixes: 897efe628d7e ("scsi: ufs: add missing memory barriers") Signed-off-by: Andrew Halaney Reviewed-by: Bart Van Assche Reviewed-by: Can Guo --- drivers/ufs/core/ufshcd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c index caebd589e08c..7c1975a1181f 100644 --- a/drivers/ufs/core/ufshcd.c +++ b/drivers/ufs/core/ufshcd.c @@ -4726,7 +4726,7 @@ int ufshcd_make_hba_operational(struct ufs_hba *hba) * Make sure base address and interrupt setup are updated before * enabling the run/stop registers below. */ - wmb(); + ufshcd_readl(hba, REG_UTP_TASK_REQ_LIST_BASE_H); /* * UCRDY, UTMRLDY and UTRLRDY bits must be 1