From patchwork Fri Mar 29 20:46:44 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Halaney X-Patchwork-Id: 13611037 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 AD78585631 for ; Fri, 29 Mar 2024 20:48:52 +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=1711745334; cv=none; b=GIEz9rOfrjXb1EuTHLxgmDsw6xOjGWvMOVR45Bkr6sw1tM5zzfGoZSnaqIda4EJ99BC+2uRYMbMAk5S/0JuN28U+K+6/8L02eC8/fC/S6RxhhJ2iZUGm1s3OoD+lDX58lE2cPDZrugpq/5hX+u5KYdaH3Lv78jDWBtoIuQbwv/E= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711745334; c=relaxed/simple; bh=noY0Ok43Br9Lq9vxVD8O578wOnnwfbfMJqrIM3jYkv0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=moSMRlFll/JlwZTtGJdKbaXylTLmVpIed/wE4jL94JBgmE0OdZzmnfFa9rHPUbnfdQfgfnawwc0pGPg3t4dEyWwykm6D2evaq5+W3/E3pINEYLtG7778Iz5TOmvHzi1ePI10I1HK9UfLigQ1y2DC1o6mPSu1dJEPkd+ly5TJUe0= 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=YGFs/+2L; 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="YGFs/+2L" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1711745331; 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=+uex28Uh2UrmMwKWwWQdWkljJkUfVw1qoAdqpkkJAvI=; b=YGFs/+2L/so5RkefOtHx1PlEAyKPR3ayWEem4sRFSWn6I9rLdflcV3p3LGBiwS8CSDflbO XwvciMh2J1z+wwe95LVuCd6Eq36YQarWz0i5Pua25rSpl0PH5oFM3BkiXwfnmptU0Ah/+M geLd/dfx4WmvZjEwk8Imhr6NCFfPHvk= Received: from mail-qv1-f72.google.com (mail-qv1-f72.google.com [209.85.219.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-13-It82g8UQO_6h4DwrU7dheQ-1; Fri, 29 Mar 2024 16:48:50 -0400 X-MC-Unique: It82g8UQO_6h4DwrU7dheQ-1 Received: by mail-qv1-f72.google.com with SMTP id 6a1803df08f44-696a266542cso20030286d6.0 for ; Fri, 29 Mar 2024 13:48:50 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1711745329; x=1712350129; 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=+uex28Uh2UrmMwKWwWQdWkljJkUfVw1qoAdqpkkJAvI=; b=SHqQFfDX5Q0XZQ8zKJt+BVUgLjzrc8z8KiwJcZENd/MUwWeQX+uFemFf7aSqAemWtV q3AVAmui3SWyNEaYM/5e266dAdvpyZdgUtfvh/0c2ypNBwR65F07fLS0Aw2hk6m9rM8u lYc3/sVzLTMMaEahxk3lqoEevxvJ6Xp+RGllhAk6bO5dMVYW257TuvLLDUxgDCv4FibP GZ37FNi6BuzgAum7YN1skAvFmYs/FdLxl22uRYqBgy9MG76DILQqWO2ctZamQAHNzNyq b20MZqQF8nbT6th9vav3+lZrXAqgegFfAVDuv7d9apbfYC3ye0hy4OeBDd7KTCpJrwqQ HF/w== X-Forwarded-Encrypted: i=1; AJvYcCUPG9cJ265gryN6QJxgxB/3H+gxD4JSe6wdwhBsPsu/3CQnjozLSQTMhv4H1Yx8p4je1Q2lgKrZenTeYDPwHQvqpvc9bTv2uiFKOtrFvQ== X-Gm-Message-State: AOJu0YyECzYPv9fnlfnEOkAP/R562DS4wLLB4nWGrdf+XfYme1MVtyZN /4V25vLTHOmWHrEN8tF0fyVdq54oIn8d+tJlCkWGN9ahJl6DpVe1xHg36igl7RrlnhDl90JWUB9 6gd/CcNwWQVIah+H/8wrXaAowXOT9dA4zuw0xxFvS9/Ua+AEHU//ivYm2fGbQrdE= X-Received: by 2002:a0c:b542:0:b0:696:a324:cd9e with SMTP id w2-20020a0cb542000000b00696a324cd9emr3095518qvd.29.1711745328980; Fri, 29 Mar 2024 13:48:48 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFvBfgYmwP1iGTeLUYx8CVUhOtv1wYg6+LYE6N5bTtRV/i7BJo/aa22Q4+l3Q6ah0cplyRTFg== X-Received: by 2002:a0c:b542:0:b0:696:a324:cd9e with SMTP id w2-20020a0cb542000000b00696a324cd9emr3095504qvd.29.1711745328590; Fri, 29 Mar 2024 13:48:48 -0700 (PDT) Received: from x1gen2nano.redhat.com ([2600:1700:1ff0:d0e0::33]) by smtp.gmail.com with ESMTPSA id jz10-20020a0562140e6a00b00698f27c6460sm794271qvb.110.2024.03.29.13.48.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 29 Mar 2024 13:48:45 -0700 (PDT) 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 , Anjana Hari Cc: Andrew Halaney , Will Deacon , linux-arm-msm@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v5 02/11] scsi: ufs: qcom: Perform read back after writing REG_UFS_SYS1CLK_1US Date: Fri, 29 Mar 2024 15:46:44 -0500 Message-ID: <20240329-ufs-reset-ensure-effect-before-delay-v5-2-181252004586@redhat.com> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240329-ufs-reset-ensure-effect-before-delay-v5-0-181252004586@redhat.com> References: <20240329-ufs-reset-ensure-effect-before-delay-v5-0-181252004586@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 0.13.0 Currently after writing to REG_UFS_SYS1CLK_1US a mb() is used to ensure that write has gone through to the device. 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") Reviewed-by: Can Guo Signed-off-by: Andrew Halaney Reviewed-by: Manivannan Sadhasivam --- 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 06859e17b67b..804dc8153e7b 100644 --- a/drivers/ufs/host/ufs-qcom.c +++ b/drivers/ufs/host/ufs-qcom.c @@ -501,7 +501,7 @@ static int ufs_qcom_cfg_timers(struct ufs_hba *hba, u32 gear, * make sure above write gets applied before we return from * this function. */ - mb(); + ufshcd_readl(hba, REG_UFS_SYS1CLK_1US); } return 0;