From patchwork Mon Jan 22 17:24:02 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Halaney X-Patchwork-Id: 764696 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 DA21653E16 for ; Mon, 22 Jan 2024 17:24:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705944277; cv=none; b=RiP0q5hZtUgQHIxLL7g4Gcg2asAi43rpGnAAgawEGp2Fq9r5nB0JCi3/ND/8J3Iq8o4+h3vsJbZ1F7FJf73TJUJL1M/k8GqCpMZu4vSJs8wfoWpIbr0X2hRrL8qRZJkcalMkPjbkXn3CQ4M8b8khMgkjfI26lUlJxAVFNidBcxc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705944277; c=relaxed/simple; bh=s5zG+L/VGA4r6opNYDq/X6r4u7Dz3JHhUiw1v8rHzzI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=qZpm3sQxPjY6YhrFSdOXa1rtOU8bpv2QgYPZ69HEa2gQKeAC8Xh9bS9rGYhLRcJWCHZUeiBZmwc2WEz6oiski3VmZY0kgOf4fyFr+VASi+dpnq2NbBAVKWtXoNYp8rO72USplzNM90Oiatmv4sTTGwKv+iuPl/wSPYKjm+Bh/EY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=KivX6ADN; arc=none smtp.client-ip=170.10.129.124 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="KivX6ADN" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1705944275; 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=Nbn1T5pI3z/UbfuUYU7cHvzOeNQR0JNnB8PBypvklZ8=; b=KivX6ADNIhY09GWVp6p/rIPXt3HB/0dprmGN1wVELq+p/ac59OI0MOLc4GOCL33VuM08js vxcy/NibpgP1AvvfMlvkS03zt6FfyLVP2qbRiJHBEH5G4+BB7Tx711SOgkrTm956HEdQ7r APYCpCyA83sj0rKG7d8x0CPQJwbElNo= Received: from mail-qk1-f199.google.com (mail-qk1-f199.google.com [209.85.222.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-471-rjUxsNHlNM--AaxEB7fm-g-1; Mon, 22 Jan 2024 12:24:33 -0500 X-MC-Unique: rjUxsNHlNM--AaxEB7fm-g-1 Received: by mail-qk1-f199.google.com with SMTP id af79cd13be357-7835bb86ca6so578389385a.2 for ; Mon, 22 Jan 2024 09:24:33 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1705944271; x=1706549071; 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=Nbn1T5pI3z/UbfuUYU7cHvzOeNQR0JNnB8PBypvklZ8=; b=OCOmlfFPFGwTbyWXHscnCgLcSiKx/uFerirOZKmRk9fVOv9aXS2Mb/bZGo0ZMG0U5j +HfJhAkr5e2ukGFGojeoi/tTOjA6WWwaRjy3slJUVtbY/4IgJYYobUMO7jdR83V8NNOq thEoNsa8u+7VQ1WEF7UniD54ZcNKi+bMoDTVf3yrFr+P3rv6nwmAmYNJ0HAe0nSPB08n WkLDut3skvbdyZE7+E50P8p8eDZHoIPVjL/YCZERcwwr/tkleDUwlkE4mZrqT13dyq9s FMKNhKib+KOt2X/QJa9Zv2kIGfaAk9kaHLiDppWwMEor2CfeGJ7SJuADcCY6K/F4lrPF xG7g== X-Gm-Message-State: AOJu0YxrdtqRx6rOctiNOWfdT+yJzcL6NpNf+OB3BK6P7j9dBX1+B+Uu BDKYKqk2M3vM0nbAJx4d7X0uVuwU1FPjKFEZSCJ+vLA88JihlQPlt77s5NT3NUGLLz+NYLGVHzZ YfqgMTnf3+4QuUDAlYtVRHQiQWimoKX76Ab5tJ7dBXv6Kxwi4hRMhfKkrgNt7bIM= X-Received: by 2002:a05:620a:4092:b0:783:a2ba:eebc with SMTP id f18-20020a05620a409200b00783a2baeebcmr1181207qko.24.1705944271366; Mon, 22 Jan 2024 09:24:31 -0800 (PST) X-Google-Smtp-Source: AGHT+IH+cIRyR7E/BPa15GlhIFB+sJnWKn/RhvzQjmmC1gCPckHcfoCIOnQhcFc6TJFKCb9MtxlDLw== X-Received: by 2002:a05:620a:4092:b0:783:a2ba:eebc with SMTP id f18-20020a05620a409200b00783a2baeebcmr1181193qko.24.1705944270958; Mon, 22 Jan 2024 09:24:30 -0800 (PST) Received: from fedora.redhat.com ([2600:1700:1ff0:d0e0::37]) by smtp.gmail.com with ESMTPSA id c7-20020a05620a200700b00781ae860c31sm2280992qka.70.2024.01.22.09.24.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Jan 2024 09:24:30 -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, Manivannan Sadhasivam Subject: [PATCH RFC v4 06/11] scsi: ufs: cdns-pltfrm: Perform read back after writing HCLKDIV Date: Mon, 22 Jan 2024 11:24:02 -0600 Message-ID: <20240122-ufs-reset-ensure-effect-before-delay-v4-6-90a54c832508@redhat.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240122-ufs-reset-ensure-effect-before-delay-v4-0-90a54c832508@redhat.com> References: <20240122-ufs-reset-ensure-effect-before-delay-v4-0-90a54c832508@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, HCLKDIV is written to and then 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: d90996dae8e4 ("scsi: ufs: Add UFS platform driver for Cadence UFS") Reviewed-by: Manivannan Sadhasivam Signed-off-by: Andrew Halaney --- drivers/ufs/host/cdns-pltfrm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/ufs/host/cdns-pltfrm.c b/drivers/ufs/host/cdns-pltfrm.c index bb30267da471..66811d8d1929 100644 --- a/drivers/ufs/host/cdns-pltfrm.c +++ b/drivers/ufs/host/cdns-pltfrm.c @@ -136,7 +136,7 @@ static int cdns_ufs_set_hclkdiv(struct ufs_hba *hba) * Make sure the register was updated, * UniPro layer will not work with an incorrect value. */ - mb(); + ufshcd_readl(hba, CDNS_UFS_REG_HCLKDIV); return 0; }