Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755476AbdLTPbW (ORCPT ); Wed, 20 Dec 2017 10:31:22 -0500 Received: from mail-wm0-f46.google.com ([74.125.82.46]:46268 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755121AbdLTPbU (ORCPT ); Wed, 20 Dec 2017 10:31:20 -0500 X-Google-Smtp-Source: ACJfBou24d2/5CsDnLLnNdsO+RdsmtEala4IHmui/imjgz8hE9qz/DZxT9pFKo27Xpg4zfUu73B1nQ== Subject: Re: [PATCH 0/4] tpm: fix PS/2 devices not working on Braswell systems due CLKRUN enabled To: "Shaikh, Azhar" , "Alexander.Steffen@infineon.com" , "hdegoede@redhat.com" , "linux-kernel@vger.kernel.org" Cc: "james@ettle.org.uk" , "arnd@arndb.de" , "jarkko.sakkinen@linux.intel.com" , "peterhuewe@gmx.de" , "jgg@ziepe.ca" , "gregkh@linuxfoundation.org" , "linux-integrity@vger.kernel.org" References: <20171220113538.16099-1-javierm@redhat.com> <96f3f833-22f8-5400-bd22-7c1c622bbe61@redhat.com> <5FFFAD06ADE1CA4381B3F0F7C6AF58289886F4@ORSMSX109.amr.corp.intel.com> From: Javier Martinez Canillas Message-ID: Date: Wed, 20 Dec 2017 16:31:17 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: <5FFFAD06ADE1CA4381B3F0F7C6AF58289886F4@ORSMSX109.amr.corp.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1503 Lines: 33 Hello Azhar, On 12/20/2017 04:08 PM, Shaikh, Azhar wrote: [snip] >>> >>>> It seems that on machines with a PS/2 controller connected to the >>>> LPC bus the BIOS is already doing this, so I've a feeling that it >>>> not being done on devices with a TPM is a bug in the firmware >>> >>> Absolutely agree, system integratos should make sure that all the >>> devices connected to the LPC either have CLKRUN protocol support and >>> is enabled or disable the CLKRUN protocol permanently. >> >> As far as I understand it, this is exactly the issue here: They know that there >> are devices that do not support the CLKRUN protocol (the TPM in this case), >> but they still need to enable it to prevent other issues. So for the TPM to >> continue to work, CLKRUN needs to be disabled temporarily while the TPM is >> active. >> > > Yes that was the reason to have this fix. We needed CLKRUN to be enabled for Braswell SOC . But the TPM in this case SLB9655 does not support CLKRUN (please check this public documentation https://www.infineon.com/dgdl/Infineon-TPM+SLB+9665-DS-v10_15-EN.pdf?fileId=5546d4625185e0e201518b83d9273d87 section 2.3 Power Management). So as Alexander mentioned CLKRUN is disabled while TPM transactions are in progress. > Yes I do understand that. Please read my answer to Alexander's email and also my question (and Hans') about keeping the CLKRUN protocol permanently disabled. Best regards, -- Javier Martinez Canillas Software Engineer - Desktop Hardware Enablement Red Hat