linux-kernel - Re: [PATCH v10 4/7] i2c: fsi: Add abort and hardware reset procedures

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Message-ID: <20180626023849.op4rimmsnlv4rgwg@ninjato>
Date:   Tue, 26 Jun 2018 11:38:49 +0900
From:   Wolfram Sang <wsa@...-dreams.de>
To:     Eddie James <eajames@...ux.vnet.ibm.com>
Cc:     linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, robh+dt@...nel.org,
        benh@...nel.crashing.org, joel@....id.au, mark.rutland@....com,
        gregkh@...uxfoundation.org, rdunlap@...radead.org,
        andy.shevchenko@...il.com, peda@...ntia.se
Subject: Re: [PATCH v10 4/7] i2c: fsi: Add abort and hardware reset procedures

On Wed, Jun 13, 2018 at 02:36:16PM -0500, Eddie James wrote:
> Add abort procedure for failed transfers. Add engine and bus reset
> procedures to recover from as many faults as possible.

I think this is a way too aggressive recovery. Your are doing the 9
pulse toggles basically on any error while this is only when the device
keeps SDA low and you want to recover from that. If SDA is not stuck
low, sending a STOP should do. Or do you have a known case where this is
not going to work?

Also, you implement the pulse toggling manually. Can't you just populate
{get|set}_{scl|sda} and use the generic routine we have in the core?