linux-kernel - Re: [PATCH v2] Input: elan_i2c - check if device is there before really probing

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Message-ID: <20170510004654.GC32584@dtor-ws>
Date:   Tue, 9 May 2017 17:46:54 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Fabio Estevam <festevam@...il.com>
Cc:     linux-input@...r.kernel.org, KT Liao <ktalex.liao@...il.com>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Guenter Roeck <linux@...ck-us.net>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] Input: elan_i2c - check if device is there before
 really probing

On Mon, May 08, 2017 at 10:43:36PM -0300, Fabio Estevam wrote:
> On Mon, May 8, 2017 at 9:45 PM, Dmitry Torokhov
> <dmitry.torokhov@...il.com> wrote:
> 
> > +       /* Make sure there is something at this address */
> > +       error = i2c_smbus_read_byte(client);
> > +       if (error < 0) {
> > +               dev_dbg(&client->dev, "nothing at this address: %d\n", error);
> > +               return -ENXIO;
> 
> You could return the real error code here: 'return error'

That is the point of the patch - we want to fail silently if the device
is not actually there and fails even the simplest communication. Driver
core treats ENXIO and ENODEV as special and does not log errors.

Thanks.

-- 
Dmitry