linux-kernel - Re: [PATCH] i2c: mux: demux-pinctrl: do not deactivate a master that is not active

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Date:   Wed, 2 Mar 2022 23:45:57 +0100
From:   Peter Rosin <peda@...ntia.se>
To:     Wolfram Sang <wsa+renesas@...g-engineering.com>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] i2c: mux: demux-pinctrl: do not deactivate a master that
 is not active

On 2022-03-02 22:22, Wolfram Sang wrote:
> On Wed, Mar 02, 2022 at 10:17:20PM +0100, Wolfram Sang wrote:
>>
>>> Attempting to rollback the activation of the current master when
>>> the current master has not been activated is bad. priv->cur_chan
>>
>> But the master is activated?
>>
>> 259         /* switch to first parent as active master */
>> 260         i2c_demux_activate_master(priv, 0);
>>
>> Or am I missing something? :)
> 
> But _this_ code is affected by the problem you describe, or?
> 
> 237                 if (!adap_np) {
> 238                         dev_err(&pdev->dev, "can't get phandle for parent %d\n", i);
> 239                         err = -ENOENT;
> 240                         goto err_rollback;
> 241                 }
> 

Yes. That is the error path that, if taken, results in the faulty
deactivation. Sorry for not spelling it out...

Cheers,
Peter