Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1752523AbdHOWCU (ORCPT <rfc822;w@1wt.eu>);
        Tue, 15 Aug 2017 18:02:20 -0400
Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:43449 "EHLO
        mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL)
        by vger.kernel.org with ESMTP id S1751471AbdHOWCS (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 15 Aug 2017 18:02:18 -0400
Subject: Re: [tpmdd-devel] [PATCH] tpm: improve tpm_tis send() performance by
 ignoring burstcount
Cc: linux-ima-devel@lists.sourceforge.net,
        linux-security-module@vger.kernel.org,
        tpmdd-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org
References: <20170807114632.1339-1-nayna@linux.vnet.ibm.com>
 <E37DFCB0-2E74-45F6-B2DF-70EF59F310BC@gmx.de>
 <20170808191145.kggmoczd5laiccrn@linux.intel.com>
 <db0359cc-5e6b-2055-734a-bd9104e4a99f@linux.vnet.ibm.com>
 <trinity-b615e596-8095-4a0a-9922-3fa9a5724c30-1502312435959@3c-app-gmx-bs76>
 <9cb350b6-32fd-529e-eb31-6800339cddb2@linux.vnet.ibm.com>
 <20170814015359.30177c87@naga>
From: Ken Goldman <kgold@linux.vnet.ibm.com>
Date: Tue, 15 Aug 2017 18:02:57 -0400
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101
 Thunderbird/52.2.1
MIME-Version: 1.0
In-Reply-To: <20170814015359.30177c87@naga>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
X-TM-AS-GCONF: 00
x-cbid: 17081522-0004-0000-0000-000012C116D9
X-IBM-SpamModules-Scores: 
X-IBM-SpamModules-Versions: BY=3.00007551; HX=3.00000241; KW=3.00000007;
 PH=3.00000004; SC=3.00000221; SDB=6.00902845; UDB=6.00452220; IPR=6.00683060;
 BA=6.00005534; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000;
 ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00016712; XFM=3.00000015;
 UTC=2017-08-15 22:02:14
X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused
x-cbparentid: 17081522-0005-0000-0000-000080B397A1
Message-Id: <869cc1b1-0836-a53b-31d7-9fec50d8cc52@linux.vnet.ibm.com>
X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-08-15_14:,,
 signatures=0
X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0
 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam
 adjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000
 definitions=main-1708150358
To: unlisted-recipients:; (no To-header on input)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 620
Lines: 15

On 8/13/2017 7:53 PM, msuchanek wrote:
> About 500 out of 700 mainboards sold today has a PS/2 port which is
> probably due to prevalence of legacy devices and usbhid limitations.
> 
> Similarily many boards have serial and parallel hardware ports.
> 
> In all diagrams detailed enough to show these ports I have seen them
> attached to the LPC bus.

Do these boards have a TPM?  Remember that the TPM requires special LPC 
bus cycles.

Even if so, the TPM LPC bus wait states are less than a usec.  My 
thought is that  it's unlikely that any device (serial port, mouse, 
keyboard, printer) will be adversely affected.