From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <eajames@linux.vnet.ibm.com>
Authentication-Results: lists.ozlabs.org;
 spf=none (mailfrom) smtp.mailfrom=linux.vnet.ibm.com
 (client-ip=148.163.156.1; helo=mx0a-001b2d01.pphosted.com;
 envelope-from=eajames@linux.vnet.ibm.com; receiver=<UNKNOWN>)
Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none)
 header.from=linux.vnet.ibm.com
Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com
 [148.163.156.1])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (No client certificate requested)
 by lists.ozlabs.org (Postfix) with ESMTPS id 40lf8p61nmzF2Pf
 for <openbmc@lists.ozlabs.org>; Tue, 15 May 2018 23:50:33 +1000 (AEST)
Received: from pps.filterd (m0098399.ppops.net [127.0.0.1])
 by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id
 w4FDk6FS079007
 for <openbmc@lists.ozlabs.org>; Tue, 15 May 2018 09:50:31 -0400
Received: from e33.co.us.ibm.com (e33.co.us.ibm.com [32.97.110.151])
 by mx0a-001b2d01.pphosted.com with ESMTP id 2hyxsjx7yy-1
 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT)
 for <openbmc@lists.ozlabs.org>; Tue, 15 May 2018 09:50:30 -0400
Received: from localhost
 by e33.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only!
 Violators will be prosecuted
 for <openbmc@lists.ozlabs.org> from <eajames@linux.vnet.ibm.com>;
 Tue, 15 May 2018 07:50:30 -0600
Received: from b03cxnp08025.gho.boulder.ibm.com (9.17.130.17)
 by e33.co.us.ibm.com (192.168.1.133) with IBM ESMTP SMTP Gateway: Authorized
 Use Only! Violators will be prosecuted; 
 Tue, 15 May 2018 07:50:27 -0600
Received: from b03ledav002.gho.boulder.ibm.com
 (b03ledav002.gho.boulder.ibm.com [9.17.130.233])
 by b03cxnp08025.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id
 w4FDoRX215728944; Tue, 15 May 2018 06:50:27 -0700
Received: from b03ledav002.gho.boulder.ibm.com (unknown [127.0.0.1])
 by IMSVA (Postfix) with ESMTP id 4938013604D;
 Tue, 15 May 2018 07:50:27 -0600 (MDT)
Received: from [9.85.138.239] (unknown [9.85.138.239])
 by b03ledav002.gho.boulder.ibm.com (Postfix) with ESMTP id 939B9136040;
 Tue, 15 May 2018 07:50:26 -0600 (MDT)
Subject: Re: [PATCH linux dev-4.13 0/2] Fix SBEFIFO chardev read behaviour
To: Andrew Jeffery <andrew@aj.id.au>, joel@jms.id.au
Cc: openbmc@lists.ozlabs.org
References: <20180514061809.11487-1-andrew@aj.id.au>
 <b73439a1-ea2e-0352-d7b1-440bdf2243f6@linux.vnet.ibm.com>
 <1526339340.3483421.1372054976.4F9E0D27@webmail.messagingengine.com>
From: Eddie James <eajames@linux.vnet.ibm.com>
Date: Tue, 15 May 2018 08:50:25 -0500
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.7.0
MIME-Version: 1.0
In-Reply-To: <1526339340.3483421.1372054976.4F9E0D27@webmail.messagingengine.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Content-Language: en-US
X-TM-AS-GCONF: 00
x-cbid: 18051513-0008-0000-0000-000009C882E1
X-IBM-SpamModules-Scores: 
X-IBM-SpamModules-Versions: BY=3.00009029; HX=3.00000241; KW=3.00000007;
 PH=3.00000004; SC=3.00000260; SDB=6.01032669; UDB=6.00527956; IPR=6.00811800; 
 MB=3.00021126; MTD=3.00000008; XFM=3.00000015; UTC=2018-05-15 13:50:29
X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused
x-cbparentid: 18051513-0009-0000-0000-000047481C3C
Message-Id: <0d5c838f-3eff-d99e-c8f8-6d50302a891d@linux.vnet.ibm.com>
X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, ,
 definitions=2018-05-15_04:, , signatures=0
X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0
 priorityscore=1501
 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0
 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0
 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000
 definitions=main-1805150140
X-BeenThere: openbmc@lists.ozlabs.org
X-Mailman-Version: 2.1.26
Precedence: list
List-Id: Development list for OpenBMC <openbmc.lists.ozlabs.org>
List-Unsubscribe: <https://lists.ozlabs.org/options/openbmc>,
 <mailto:openbmc-request@lists.ozlabs.org?subject=unsubscribe>
List-Archive: <http://lists.ozlabs.org/pipermail/openbmc/>
List-Post: <mailto:openbmc@lists.ozlabs.org>
List-Help: <mailto:openbmc-request@lists.ozlabs.org?subject=help>
List-Subscribe: <https://lists.ozlabs.org/listinfo/openbmc>,
 <mailto:openbmc-request@lists.ozlabs.org?subject=subscribe>
X-List-Received-Date: Tue, 15 May 2018 13:50:35 -0000



On 05/14/2018 06:09 PM, Andrew Jeffery wrote:
> Hi Eddie,
>
> On Tue, 15 May 2018, at 07:57, Eddie James wrote:
>>
>> On 05/14/2018 01:18 AM, Andrew Jeffery wrote:
>>> Hello,
>>>
>>> read() on the SBEFIFO chardevs is currently unusuable as it will always return
>>> -EAGAIN on a read subsequent to the EOT flag being observed. This breaks reads
>>> using short buffers as we now have no way to know when we have received the
>>> entire message. This is made infinitely worse by the protocol, which as
>>> defined, means we cannot know how much data must be read, and therefore all
>>> buffers are effectively short*.
>>>
>>> These two patches help by at least returning 0 for a read subsequent to one
>>> which drains the last byte from the transfer buffer. A read subsequent to one
>>> returning 0 will then return -EAGAIN if necessary, under the expectation that a
>>> write() has been issued.
>> Thanks Andrew, I haven't dug into the diffs too much but I just tested
>> the series and it appears to have made the in-kernel API less reliable.
>> I'm getting some errors when attempting to use the OCC driver.
> Thanks for testing. What errors are you sometimes seeing? I need some more info to reproduce and understand what might be going wrong.

Any of EIO, ENODATA, and EBADMSG from the OCC driver. All I did was 
power the system on, and would see the errors most of the time when the 
host attempted to set the OCCs active.

Thanks,
Eddie

>
> Cheers,
>
> Andrew
>