linux-kernel - Re: [PATCH 1/1] media: dvb_dummy_tuner: implement driver skeleton

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Date:   Thu, 9 Jan 2020 16:54:37 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     "Daniel W. S. Almeida" <dwlsalmeida@...il.com>
Cc:     mchehab@...nel.org, sean@...s.org, tglx@...utronix.de,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        skhan@...uxfoundation.org,
        linux-kernel-mentees@...ts.linuxfoundation.org
Subject: Re: [PATCH 1/1] media: dvb_dummy_tuner: implement driver skeleton

On Thu, Jan 09, 2020 at 12:24:08PM -0300, Daniel W. S. Almeida wrote:
> +static int dvb_dummy_tuner_i2c_probe(struct i2c_client *client,
> +				     const struct i2c_device_id *id)
> +{
> +	int ret = 0;
> +	struct dvb_dummy_tuner_config *config = client->dev.platform_data;
> +	struct dvb_frontend *fe = config->fe;
> +	struct dvb_dummy_tuner_dev *tuner_dev = NULL;
> +
> +	tuner_dev = kzalloc(sizeof(*tuner_dev), GFP_KERNEL);
> +	if (!tuner_dev) {
> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +
> +	i2c_set_clientdata(client, tuner_dev);
> +	tuner_dev->fe = config->fe;
> +
> +	memcpy(&fe->ops.tuner_ops,
> +	       &dvb_dummy_tuner_ops,
> +	       sizeof(struct dvb_tuner_ops));
> +
> +	fe->tuner_priv = client;
> +
> +	pr_debug("%s: Successfully probed %s\n", __func__, client->name);

As you are a driver, you should never need to call any pr_* calls,
instead use dev_*().  For this, you can use dev_dbg(), but really, why
is that even needed except for your debugging bringup.  And for that,
you can use ftrace, right?  So no need for any printing of anything
here.

> +	return ret;
> +
> +err:
> +	pr_err("%s: failed\n", __func__);

Again, dev_err() would be proper, but there's no need for any error
message here.


Don't you need to register the tuner ops with something in this
function?

> +	return ret;
> +}
> +
> +static int dvb_dummy_tuner_i2c_remove(struct i2c_client *client)
> +{
> +	struct dvb_dummy_tuner_dev *tuner_dev = i2c_get_clientdata(client);
> +	struct dvb_frontend *fe = tuner_dev->fe;
> +
> +	memset(&fe->ops.tuner_ops, 0, sizeof(struct dvb_tuner_ops));
> +	fe->tuner_priv = NULL;
> +	kfree(tuner_dev);
> +

Don't you need to unregister the tuner ops in here?

thanks,

greg k-h