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Subject: Re: [PATCH 1/1] media: dvb_dummy_tuner: implement driver skeleton
To:     "Daniel W. S. Almeida" <dwlsalmeida@gmail.com>, mchehab@kernel.org,
        sean@mess.org, tglx@linutronix.de, gregkh@linuxfoundation.org
Cc:     linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-kernel-mentees@lists.linuxfoundation.org,
        Shuah Khan <skhan@linuxfoundation.org>
References: <20200109152408.919325-1-dwlsalmeida@gmail.com>
 <20200109152408.919325-2-dwlsalmeida@gmail.com>
From:   Shuah Khan <skhan@linuxfoundation.org>
Message-ID: <5f296977-6aac-cfd9-9082-ff824f85ab43@linuxfoundation.org>
Date:   Thu, 9 Jan 2020 09:45:33 -0700
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Hi Daniel,

On 1/9/20 8:24 AM, Daniel W. S. Almeida wrote:
> From: "Daniel W. S. Almeida" <dwlsalmeida@gmail.com>
> 
> Implement the skeleton for the tuner driver in a separate file.

Please add more detail here on what this driver does. What this
driver is used for and so on.

> 
> Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@gmail.com>
> ---
>   drivers/media/tuners/Kconfig           |   7 ++
>   drivers/media/tuners/Makefile          |   1 +
>   drivers/media/tuners/dvb_dummy_tuner.c | 153 +++++++++++++++++++++++++
>   drivers/media/tuners/dvb_dummy_tuner.h |  20 ++++
>   4 files changed, 181 insertions(+)
>   create mode 100644 drivers/media/tuners/dvb_dummy_tuner.c
>   create mode 100644 drivers/media/tuners/dvb_dummy_tuner.h
> 
> diff --git a/drivers/media/tuners/Kconfig b/drivers/media/tuners/Kconfig
> index e104bb7766e1..efa1591fe0ae 100644
> --- a/drivers/media/tuners/Kconfig
> +++ b/drivers/media/tuners/Kconfig
> @@ -296,4 +296,11 @@ config MEDIA_TUNER_QM1D1B0004
>   	default m if !MEDIA_SUBDRV_AUTOSELECT
>   	help
>   	  Sharp QM1D1B0004 ISDB-S tuner driver.
> +
> +config MEDIA_TUNER_DVB_DUMMY_TUNER
> +	tristate "Dummy tuner"
> +	depends on MEDIA_SUPPORT && I2C
> +	default m if !MEDIA_SUBDRV_AUTOSELECT
> +	help
> +	  Dummy tuner driver for common TV standards.

Samehere. Give more details on what this driver does. Add enough detail
to help users decide why they should enable it or not.

>   endmenu
> diff --git a/drivers/media/tuners/Makefile b/drivers/media/tuners/Makefile
> index 7b4f8423501e..f98de1cf2e19 100644
> --- a/drivers/media/tuners/Makefile
> +++ b/drivers/media/tuners/Makefile
> @@ -44,5 +44,6 @@ obj-$(CONFIG_MEDIA_TUNER_QM1D1C0042) += qm1d1c0042.o
>   obj-$(CONFIG_MEDIA_TUNER_QM1D1B0004) += qm1d1b0004.o
>   obj-$(CONFIG_MEDIA_TUNER_M88RS6000T) += m88rs6000t.o
>   obj-$(CONFIG_MEDIA_TUNER_TDA18250) += tda18250.o
> +obj-$(CONFIG_MEDIA_TUNER_DVB_DUMMY_TUNER) += dvb_dummy_tuner.o
>   
>   ccflags-y += -I$(srctree)/drivers/media/dvb-frontends
> diff --git a/drivers/media/tuners/dvb_dummy_tuner.c b/drivers/media/tuners/dvb_dummy_tuner.c
> new file mode 100644
> index 000000000000..63d2e47d4739
> --- /dev/null
> +++ b/drivers/media/tuners/dvb_dummy_tuner.c
> @@ -0,0 +1,153 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + *  Driver for Dummy Frontend
> + *
> + *  Written by Daniel W. S. Almeida <dwlsalmeida@gmail.com>

General practice is the following.

Copyright (c) 2020 Daniel W. S. Almeida <dwlsalmeida@gmail.com>

> + */
> +
> +#include <linux/errno.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +#include <media/dvb_frontend.h>
> +#include "dvb_dummy_tuner.h"
> +
> +struct dvb_dummy_tuner_dev {
> +	struct dvb_frontend *fe;
> +};
> +
> +static void dvb_dummy_tuner_release(struct dvb_frontend *fe)
> +{
> +}
> +
> +static int dvb_dummy_tuner_init(struct dvb_frontend *fe)
> +{
> +	return 0;
> +}
> +
> +static int dvb_dummy_tuner_sleep(struct dvb_frontend *fe)
> +{
> +	return 0;
> +}
> +
> +static int dvb_dummy_tuner_suspend(struct dvb_frontend *fe)
> +{
> +	return 0;
> +}
> +
> +static int dvb_dummy_tuner_resume(struct dvb_frontend *fe)
> +{
> +	return 0;
> +}
> +
> +static int dvb_dummy_tuner_set_params(struct dvb_frontend *fe)
> +{
> +	return 0;
> +}
> +
> +static int dvb_dummy_tuner_set_config(struct dvb_frontend *fe, void *priv_cfg)
> +{
> +	return 0;
> +}
> +
> +static int dvb_dummy_tuner_get_frequency(struct dvb_frontend *fe,
> +					 u32 *frequency)
> +{
> +	return 0;
> +}
> +
> +static int dvb_dummy_tuner_get_bandwidth(struct dvb_frontend *fe,
> +					 u32 *bandwidth)
> +{
> +	return 0;
> +}
> +
> +static int dvb_dummy_tuner_get_if_frequency(struct dvb_frontend *fe,
> +					    u32 *frequency)
> +{
> +	return 0;
> +}
> +
> +static int dvb_dummy_tuner_get_status(struct dvb_frontend *fe, u32 *status)
> +{
> +	return 0;
> +}
> +
> +static const struct dvb_tuner_ops dvb_dummy_tuner_ops = {
> +	.release = dvb_dummy_tuner_release,
> +	.init = dvb_dummy_tuner_init,
> +	.sleep = dvb_dummy_tuner_sleep,
> +	.suspend = dvb_dummy_tuner_suspend,
> +	.resume = dvb_dummy_tuner_resume,
> +	.set_params = dvb_dummy_tuner_set_params,
> +	.set_config = dvb_dummy_tuner_set_config,
> +	.get_bandwidth = dvb_dummy_tuner_get_bandwidth,
> +	.get_frequency = dvb_dummy_tuner_get_frequency,
> +	.get_if_frequency = dvb_dummy_tuner_get_if_frequency,
> +	.get_status = dvb_dummy_tuner_get_status,
> +};
> +
> +static const struct i2c_device_id dvb_dummy_tuner_i2c_id_table[] = {
> +	{"dvb_dummy_tuner", 0},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, dvb_dummy_tuner_i2c_id_table);
> +
> +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);
> +	return ret;
> +
> +err:
> +	pr_err("%s: failed\n", __func__);
> +	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);
> +
> +	return 0;
> +}
> +
> +static struct i2c_driver dvb_dummy_tuner_i2c_driver = {
> +	.driver = {
> +		.name = "dvb_dummy_tuner",
> +		.suppress_bind_attrs = true,
> +	},
> +	.probe		= dvb_dummy_tuner_i2c_probe,
> +	.remove		= dvb_dummy_tuner_i2c_remove,
> +	.id_table	= dvb_dummy_tuner_i2c_id_table,
> +};
> +module_i2c_driver(dvb_dummy_tuner_i2c_driver);
> +
> +MODULE_DESCRIPTION("DVB Dummy Tuner");
> +MODULE_AUTHOR("Daniel W. S. Almeida");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/media/tuners/dvb_dummy_tuner.h b/drivers/media/tuners/dvb_dummy_tuner.h
> new file mode 100644
> index 000000000000..fde7628258fa
> --- /dev/null
> +++ b/drivers/media/tuners/dvb_dummy_tuner.h
> @@ -0,0 +1,20 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * DVB Dummy Tuner
> + *

Please add details about the driver similar to the .c file.

> + */
> +#ifndef __TUNER_DVB_DUMMY_TUNER_H__
> +#define __TUNER_DVB_DUMMY_TUNER_H__
> +
> +#include <media/dvb_frontend.h>
> +/**
> + * struct dvb_dummy_tuner_config - configuration parameters for the dummy tuner
> + *
> + * @fe:
> + *	frontend returned by driver
> + */
> +struct dvb_dummy_tuner_config {
> +	struct dvb_frontend *fe;
> +};
> +
> +#endif /*__TUNER_DVB_DUMMY_TUNER_H__ */
> 


Looks like there is more code to be added to register/unregister

thanks,
-- Shuah