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: 13502564 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 BF70D768FE for ; Thu, 21 Dec 2023 19:10:53 +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="IV+I3KR7" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1703185852; 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=IV+I3KR7V90eENxBkyMKtn3WR96IrYLOdGxaf+tteEqSV5f+gxXUfzjpOvgxefZCt5/TTz bGgtjQ/JKsEqtlgpeTGNLGJhVAey+INFl5NjbHo4Vqd1pHAErVDYniEPGdXD0LRntOlOUv O9lOtExBg9t6TFkr45ohNic4iszHnwY= Received: from mail-qk1-f197.google.com (mail-qk1-f197.google.com [209.85.222.197]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-471-1uhOwa4yOFip1GrGIkIQfA-1; Thu, 21 Dec 2023 14:10:49 -0500 X-MC-Unique: 1uhOwa4yOFip1GrGIkIQfA-1 Received: by mail-qk1-f197.google.com with SMTP id af79cd13be357-7811e51eb8cso129395385a.1 for ; Thu, 21 Dec 2023 11:10:49 -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=gSPhv/eTWQxOWAw9QxrqJ2nFILX2taQUfRrWhiRCMFoVikW0EziczBoCt1qDTph1sN hIQ+bduIaQ+PmFwazgKtND33PHnAmircSaq+akzCh181QcQTnNo+Oy+eJcisCFG1mHsg ZL7OS4+9SpypIZEJKf9t/hjbAkF00rvGluN5GMgKlvZ/mdcg0EJVgDyPT4LMb70/4Rnp 47EeGL8r+QijIpLFhDegv1GvKvaMx6TDYt3FPQaXuSU0t86rX/uIhs873evVcz1ghVHD reTh01bMyM3047FNqvzU0l/k0qkC2A+S0Zq08Mpi6sxQpqUkB/L3d2E2JRBunViZ3+q5 ghTQ== X-Gm-Message-State: AOJu0YyRlM7L0d2kDWAKTg618o8NenJWBowE49V+cjnjuC7Qjzhru5RD iX/it9pBZKwNSV5jpFRxOwNfV/iJSpyklBNn4/BLIU0FiK2jc40+O5wDVU0Q8CFXPvGXw9ymPpw NhuuB0teKh7YRoNOCkAfAQjXBf3ZdVbFAIA== X-Received: by 2002:a37:c209:0:b0:77f:11d4:f58e with SMTP id i9-20020a37c209000000b0077f11d4f58emr286576qkm.148.1703185845415; 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-arm-msm@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 Reviewed-by: Can Guo --- 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); } /*