linux-kernel - Re: [PATCH 2/4] i2c: at91: implement i2c bus recovery

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <65d83bb0-9a0c-c6e2-1c58-cb421c69816c@electromag.com.au>
Date:   Fri, 25 Oct 2019 09:14:00 +0800
From:   Phil Reid <preid@...ctromag.com.au>
To:     Wolfram Sang <wsa@...-dreams.de>, Codrin.Ciubotariu@...rochip.com
Cc:     kamel.bouhara@...tlin.com, linux-arm-kernel@...ts.infradead.org,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        Nicolas.Ferre@...rochip.com, alexandre.belloni@...tlin.com,
        Ludovic.Desroches@...rochip.com, devicetree@...r.kernel.org,
        thomas.petazzoni@...tlin.com
Subject: Re: [PATCH 2/4] i2c: at91: implement i2c bus recovery

On 24/10/2019 23:07, Wolfram Sang wrote:
> 
>> So at the beginning of a new transfer, we should check if SDA (or SCL?)
>> is low and, if it's true, only then we should try recover the bus.
> 
> Yes, this is the proper time to do it. Remember, I2C does not define a
> timeout.
> 

FYI: Just a single poll at the start of the transfer, for it being low, will cause problems with multi-master buses.
Bus recovery should be attempted after a timeout when trying to communicate, even thou i2c doesn't define a timeout.

I'm trying to fix the designware drivers handling of this at the moment.

-- 
Regards
Phil Reid