linux-kernel - Re: [PATCH v5] i2c: imx: make bus recovery through pinctrl optional

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Date:   Mon, 12 Sep 2016 11:35:39 -0500
From:   Leo Li <pku.leo@...il.com>
To:     Tracy Smith <tlsmith3777@...il.com>
Cc:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>, linux-gpio@...r.kernel.org,
        Li Yang <leoyang.li@....com>, Stefan Agner <stefan@...er.ch>,
        Gao Pan <pandy.gao@....com>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5] i2c: imx: make bus recovery through pinctrl optional

On Wed, Sep 7, 2016 at 5:07 AM, Tracy Smith <tlsmith3777@...il.com> wrote:
> Hello, bus recovery is needed generally speaking because of potential
> protocol errors that might cause a failure condition hanging the bus.
>
> It happens frequently during bring-up of new I2C devices because firmware in
> I2C controllers fail to handle properly protocol errors.
>
> Can NXP add bus recovery for the LS1021A and LS1043A in a separate patch--
> unless there is no HW bus recovery mechanism?
>
> The concern is while fixing I.MX, NXP will fail to fix the driver bus
> recovery for the LS1021A and LS1043A and the bus will hang.
>
> If bus recovery is supported on the LS1021A and the LS1043A, a patch should
> be provided or added in this patch instead of simply disabling bus recovery.
> Request NXP to consider the patch if there is HW support for bus recovery.

FYI.  http://patchwork.ozlabs.org/patch/573879/  This seem to be the
patch you are asking for.  I have asked the original developer to
update the patch according to Wolfram's comment and work together with
the current pinctrl/gpio based recovery.  In the meanwhile you can
make use of the patch for now for LS1021A and LS1043A if necessary.

Regards,
Leo