From patchwork Thu Dec 21 19:09:50 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Halaney X-Patchwork-Id: 757404 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 3AC62745DA for ; Thu, 21 Dec 2023 19:10:50 +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="JIh3okPk" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1703185849; 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=JIh3okPkCkt3rvnCIxeRxJcwR9plzrsMGkUjUBmBTbG/pg1i4EcSFdwvX0jYUFl0ZHV3ta 0W+j+kcWicbw3t/DOSmBesypRGgqQUSgAGTLN2DNf4/SsAhL7AuU8sMblhi5eIsDWvic8c /7UoBKbmbEG98IHXzWLbs6SobYP5FRU= 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-615-s0Q3DeezM4u6gW7XCdCB8g-1; Thu, 21 Dec 2023 14:10:48 -0500 X-MC-Unique: s0Q3DeezM4u6gW7XCdCB8g-1 Received: by mail-qv1-f71.google.com with SMTP id 6a1803df08f44-67ab7e9d393so14672296d6.1 for ; Thu, 21 Dec 2023 11:10:48 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703185845; x=1703790645; 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=4219KYM+Lx5MIoMXHlnouIE3ETSXouTN4mLohiWEzAY=; b=Bhl97f43M8O5AUGB2f0vgx6B2RU4LG4Lo9qdIQ80pu79LO2YjvqkfoRcPRx8atWGlH 2PohT8gYuN//9fx2Q4TbgyTuq8zcnAlPP6xSZwVpM/e2lfhU6C99qIBO2EtB3muwStKD vVUI04xiozaIeYxnqZospFUrwosl+oVj6FuGpMqVUJsqDPmhukpwOfrrlgLY/PUZOso5 ivEGeOsYl0x5eh5EqY0e8PqwMCFeuZukR8rRFKdfNwzbNYG5z2R/XhoSW+v7WKLB5Ae1 OkROamUDzL5Alk4osAiNqHYXT9thAub8/ekdDmW/P3JevvxOQ0vRgEyeg436G+aQT5fV DkpA== X-Gm-Message-State: AOJu0YzX12/MO+AChlu5brl9qNiWxgCL4aB943syS2xS2x940rjsbJfZ vdYSDBTh4IzeBx/M1wpCfXbzJ62mFMOElTeB2XugxtOBsa1QMEI+ppPQ0i5Dcb2umY8BY+LCVMi Ot/+zlvDazxTs15uP1vI4/W80Gy+mCQ== X-Received: by 2002:a37:c209:0:b0:77f:11d4:f58e with SMTP id i9-20020a37c209000000b0077f11d4f58emr286546qkm.148.1703185845036; Thu, 21 Dec 2023 11:10:45 -0800 (PST) X-Google-Smtp-Source: AGHT+IG8jYkyl5NGRggoBhvuDpRsaNOweDEis0bQkLs57xnRD25grZcE9INmJJc/kRzCE79nsbsx3Q== X-Received: by 2002:a37:c209:0:b0:77f:11d4:f58e with SMTP id i9-20020a37c209000000b0077f11d4f58emr286537qkm.148.1703185844782; Thu, 21 Dec 2023 11:10:44 -0800 (PST) Received: from fedora.redhat.com ([2600:1700:1ff0:d0e0::37]) by smtp.gmail.com with ESMTPSA id 25-20020a05620a04d900b0077f0a4bd3c6sm846370qks.77.2023.12.21.11.10.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Dec 2023 11:10:42 -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 04/11] scsi: ufs: qcom: Perform read back after writing unipro mode Date: Thu, 21 Dec 2023 13:09:50 -0600 Message-ID: <20231221-ufs-reset-ensure-effect-before-delay-v3-4-2195a1b66d2e@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, 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); } /*