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

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Date:   Thu, 11 May 2017 13:51:32 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     linux-input@...r.kernel.org, KT Liao <ktalex.liao@...il.com>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [v2] Input: elan_i2c - check if device is there before really
 probing

On Mon, May 08, 2017 at 05:45:53PM -0700, Dmitry Torokhov wrote:
> Before trying to properly initialize the touchpad and generate bunch of
> errors, let's first see it there is anything at the given address. If we
> get error, fail silently with -ENXIO.
> 
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
> 
> v2: switched over to i2c_smbus_read_byte() as Guenter suggested
> 
>  drivers/input/mouse/elan_i2c_core.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/input/mouse/elan_i2c_core.c b/drivers/input/mouse/elan_i2c_core.c
> index 5d3b53dd2fa2..3b616cb7c67f 100644
> --- a/drivers/input/mouse/elan_i2c_core.c
> +++ b/drivers/input/mouse/elan_i2c_core.c
> @@ -1091,6 +1091,13 @@ static int elan_probe(struct i2c_client *client,
>  		return error;
>  	}
>  
> +	/* 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;
> +	}
> +
>  	/* Initialize the touchpad. */
>  	error = elan_initialize(data);
>  	if (error)