From patchwork Thu Dec 21 19:09:55 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Halaney X-Patchwork-Id: 13502569 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 E626A77B2B for ; Thu, 21 Dec 2023 19:11:14 +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="IwKJeyAb" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1703185874; 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=AWn/QHp2YPYufEDNjOJpKb2JC/5WKNiZSL7HfeI2UL8=; b=IwKJeyAbArjfgC7M4Jf0+kzeMQDhSlbxVItmPSYtPh0JJ/H/pwiGin2Z4318qCEqc8MQ20 PMDrgB14cbHL1t8KUyVlBlFi6NHyaNLzp7APe8Z977ltjnnZMd8O5wPmX+6ZGXxn80NDqb np2Ectgqwl59JhuRkMf29R8fdTNSghE= Received: from mail-qk1-f198.google.com (mail-qk1-f198.google.com [209.85.222.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-591-MfYrU0bINASgrF1Bajg2Gw-1; Thu, 21 Dec 2023 14:11:12 -0500 X-MC-Unique: MfYrU0bINASgrF1Bajg2Gw-1 Received: by mail-qk1-f198.google.com with SMTP id af79cd13be357-77d7d33b126so108126185a.2 for ; Thu, 21 Dec 2023 11:11:12 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703185872; x=1703790672; 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=AWn/QHp2YPYufEDNjOJpKb2JC/5WKNiZSL7HfeI2UL8=; b=noiPGp6quasTqNfbVGoZkGnjCWBBjUqTfeG4mrIyhARJtwlUzRuwqX/8CROGA9svYx tAYyyBkqMWBNpvaSvpLsBiwF8oBjHud9kdufaKXn8+vpoV2bmGskPCdc9301Vc6HnuHD 8F6c2Mx+kx5bIQyyEr/oL7G/4lo325+ijaqGrtDGYdVUECmyV9JWj3Gje+cfn1Ex1dsb x9vVAXYoSzUx4lhLeIwTHS3/jdzNEnjLMX4xSjaLrROUOib1i1wvJy7lfGZlrqKTbN8F ZV8KnADNtNPuW8NjJcNCQys6hDaMFE6T/1LH9lEw+SwToUqy26xowL8HtXEqbfb/uKIm LUVw== X-Gm-Message-State: AOJu0Yz3aEI/TaE0LdoiAlfsFrng4CS45w0zaV83T97eQIfbGUu0lrNS jjiyCGkEBiMDkXvIjP/Kmyaddx832dxKW+ERn9w4UGHYLgbULDMhIKUj05uO36LpMw9PiNg5X4W Ionbehqtiv49p2sqs4RY6VE+Lp4TCr/PJrw== X-Received: by 2002:a05:620a:22d2:b0:781:153b:ae6 with SMTP id o18-20020a05620a22d200b00781153b0ae6mr229443qki.107.1703185871910; Thu, 21 Dec 2023 11:11:11 -0800 (PST) X-Google-Smtp-Source: AGHT+IHbiWNqLTkVz0w6Uq+vhXvP8nkEAOb5pdCpgBAECHkBck/Eb7Lx/DDl7BzIBwYkcs/Qf08L0A== X-Received: by 2002:a05:620a:22d2:b0:781:153b:ae6 with SMTP id o18-20020a05620a22d200b00781153b0ae6mr229432qki.107.1703185871667; Thu, 21 Dec 2023 11:11:11 -0800 (PST) Received: from fedora.redhat.com ([2600:1700:1ff0:d0e0::37]) by smtp.gmail.com with ESMTPSA id 25-20020a05620a04d900b0077f0a4bd3c6sm846370qks.77.2023.12.21.11.11.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Dec 2023 11:11:11 -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 09/11] scsi: ufs: core: Perform read back after disabling UIC_COMMAND_COMPL Date: Thu, 21 Dec 2023 13:09:55 -0600 Message-ID: <20231221-ufs-reset-ensure-effect-before-delay-v3-9-2195a1b66d2e@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 UIC_COMMAND_COMPL interrupt is disabled and a wmb() is used to complete the register write before any following writes. wmb() ensures the writes complete in that order, 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 wmb()'s purpose wasn't to add extra ordering (on top of the ordering guaranteed by writel()/readl()), it can safely be removed. Fixes: d75f7fe495cf ("scsi: ufs: reduce the interrupts for power mode change requests") Signed-off-by: Andrew Halaney Reviewed-by: Bart Van Assche Reviewed-by: Can Guo Reviewed-by: Manivannan Sadhasivam --- 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 bb603769b029..75a03ee9a1ba 100644 --- a/drivers/ufs/core/ufshcd.c +++ b/drivers/ufs/core/ufshcd.c @@ -4240,7 +4240,7 @@ static int ufshcd_uic_pwr_ctrl(struct ufs_hba *hba, struct uic_command *cmd) * Make sure UIC command completion interrupt is disabled before * issuing UIC command. */ - wmb(); + ufshcd_readl(hba, REG_INTERRUPT_ENABLE); reenable_intr = true; } spin_unlock_irqrestore(hba->host->host_lock, flags);