Re: [PATCH REVIEW] e4000: convert DVB tuner to I2C driver model

[Antti Palosaari <crope@iki.fi>]

On 16.10.2013 18:54, Michael Krufky wrote:
> This kinda makes me a bit nervous.  The patch itself looks OK but the
> cascading effects that it will have across the DVB subsystem need to
> be discussed.

Basically, the only effect is that you must use i2c_new_device() or 
i2c_new_probed_device() instead of old proprietary dvb_attach(). Convert 
old proprietary method with Kernel standard one.

But thats not all. It was only first step. My final goal is to study, 
test and finally make radio tuners as a own "standalone" I2C drivers. 
This means that I will remove DVB frontend dependency next from the 
given tuner driver. And before you ask why: I need some more 
sophisticated access to tuner in order to meet SDR needs. Also I don't 
see any reason why those tuners should be a part of DVB API or part of 
V4L2 API (or even both in case of "hybrid" model). Actual reasons are 
likely payload from the history, but as of today view it is stupid design :]

> Is there a discussion about this kind of conversion on the mailing
> list somewhere that I've missed?

There has been many times around the years. i2c_new_probed_device() 
function [1] seems to be added for somehow for out needs too...

[1] http://lists.lm-sensors.org/pipermail/i2c/2007-March/000990.html


regards
Antti

>
> -Mike
>
> On Tue, Oct 15, 2013 at 7:33 PM, Mauro Carvalho Chehab
> <m.chehab@samsung.com> wrote:
>> Em Wed, 16 Oct 2013 01:31:04 +0300
>> Antti Palosaari <crope@iki.fi> escreveu:
>>
>>> Initial driver conversion from proprietary DVB tuner model to more
>>> general I2C driver model.
>>>
>>> That commit has just basic binding stuff and driver itself still
>>> needs to be converted more complete later.
>>>
>>> Cc: Jean Delvare <khali@linux-fr.org>
>>> Signed-off-by: Antti Palosaari <crope@iki.fi>
>>> ---
>>>   drivers/media/tuners/e4000.c            | 73 ++++++++++++++++++++++-----------
>>>   drivers/media/tuners/e4000.h            |  9 +++-
>>>   drivers/media/tuners/e4000_priv.h       |  4 +-
>>>   drivers/media/usb/dvb-usb-v2/rtl28xxu.c | 31 +++++++++-----
>>>   4 files changed, 78 insertions(+), 39 deletions(-)
>>>
>>> diff --git a/drivers/media/tuners/e4000.c b/drivers/media/tuners/e4000.c
>>> index 54e2d8a..f6a5dbd 100644
>>> --- a/drivers/media/tuners/e4000.c
>>> +++ b/drivers/media/tuners/e4000.c
>>> @@ -27,7 +27,7 @@ static int e4000_wr_regs(struct e4000_priv *priv, u8 reg, u8 *val, int len)
>>>        u8 buf[1 + len];
>>>        struct i2c_msg msg[1] = {
>>>                {
>>> -                     .addr = priv->cfg->i2c_addr,
>>> +                     .addr = priv->i2c_addr,
>>>                        .flags = 0,
>>>                        .len = sizeof(buf),
>>>                        .buf = buf,
>>> @@ -56,12 +56,12 @@ static int e4000_rd_regs(struct e4000_priv *priv, u8 reg, u8 *val, int len)
>>>        u8 buf[len];
>>>        struct i2c_msg msg[2] = {
>>>                {
>>> -                     .addr = priv->cfg->i2c_addr,
>>> +                     .addr = priv->i2c_addr,
>>>                        .flags = 0,
>>>                        .len = 1,
>>>                        .buf = &reg,
>>>                }, {
>>> -                     .addr = priv->cfg->i2c_addr,
>>> +                     .addr = priv->i2c_addr,
>>>                        .flags = I2C_M_RD,
>>>                        .len = sizeof(buf),
>>>                        .buf = buf,
>>> @@ -233,8 +233,8 @@ static int e4000_set_params(struct dvb_frontend *fe)
>>>         * or more.
>>>         */
>>>        f_vco = c->frequency * e4000_pll_lut[i].mul;
>>> -     sigma_delta = div_u64(0x10000ULL * (f_vco % priv->cfg->clock), priv->cfg->clock);
>>> -     buf[0] = f_vco / priv->cfg->clock;
>>> +     sigma_delta = div_u64(0x10000ULL * (f_vco % priv->clock), priv->clock);
>>> +     buf[0] = f_vco / priv->clock;
>>>        buf[1] = (sigma_delta >> 0) & 0xff;
>>>        buf[2] = (sigma_delta >> 8) & 0xff;
>>>        buf[3] = 0x00;
>>> @@ -358,17 +358,6 @@ static int e4000_get_if_frequency(struct dvb_frontend *fe, u32 *frequency)
>>>        return 0;
>>>   }
>>>
>>> -static int e4000_release(struct dvb_frontend *fe)
>>> -{
>>> -     struct e4000_priv *priv = fe->tuner_priv;
>>> -
>>> -     dev_dbg(&priv->i2c->dev, "%s:\n", __func__);
>>> -
>>> -     kfree(fe->tuner_priv);
>>> -
>>> -     return 0;
>>> -}
>>> -
>>>   static const struct dvb_tuner_ops e4000_tuner_ops = {
>>>        .info = {
>>>                .name           = "Elonics E4000",
>>> @@ -376,8 +365,6 @@ static const struct dvb_tuner_ops e4000_tuner_ops = {
>>>                .frequency_max  = 862000000,
>>>        },
>>>
>>> -     .release = e4000_release,
>>> -
>>>        .init = e4000_init,
>>>        .sleep = e4000_sleep,
>>>        .set_params = e4000_set_params,
>>> @@ -385,9 +372,12 @@ static const struct dvb_tuner_ops e4000_tuner_ops = {
>>>        .get_if_frequency = e4000_get_if_frequency,
>>>   };
>>>
>>> -struct dvb_frontend *e4000_attach(struct dvb_frontend *fe,
>>> -             struct i2c_adapter *i2c, const struct e4000_config *cfg)
>>> +static int e4000_probe(struct i2c_client *client,
>>> +             const struct i2c_device_id *id)
>>>   {
>>> +     struct e4000_config *cfg = client->dev.platform_data;
>>> +     struct dvb_frontend *fe = cfg->fe;
>>> +     struct i2c_adapter *i2c = client->adapter;
>>>        struct e4000_priv *priv;
>>>        int ret;
>>>        u8 chip_id;
>>> @@ -402,7 +392,9 @@ struct dvb_frontend *e4000_attach(struct dvb_frontend *fe,
>>>                goto err;
>>>        }
>>>
>>> -     priv->cfg = cfg;
>>> +     priv->i2c_addr = cfg->i2c_addr;
>>> +     priv->clock = cfg->clock;
>>> +     priv->i2c_client = client;
>>>        priv->i2c = i2c;
>>>
>>>        /* check if the tuner is there */
>>> @@ -412,8 +404,10 @@ struct dvb_frontend *e4000_attach(struct dvb_frontend *fe,
>>>
>>>        dev_dbg(&priv->i2c->dev, "%s: chip_id=%02x\n", __func__, chip_id);
>>>
>>> -     if (chip_id != 0x40)
>>> +     if (chip_id != 0x40) {
>>> +             ret = -ENODEV;
>>>                goto err;
>>> +     }
>>>
>>>        /* put sleep as chip seems to be in normal mode by default */
>>>        ret = e4000_wr_reg(priv, 0x00, 0x00);
>>> @@ -431,16 +425,45 @@ struct dvb_frontend *e4000_attach(struct dvb_frontend *fe,
>>>        if (fe->ops.i2c_gate_ctrl)
>>>                fe->ops.i2c_gate_ctrl(fe, 0);
>>>
>>> -     return fe;
>>> +     i2c_set_clientdata(client, priv);
>>> +
>>> +     return 0;
>>>   err:
>>>        if (fe->ops.i2c_gate_ctrl)
>>>                fe->ops.i2c_gate_ctrl(fe, 0);
>>>
>>>        dev_dbg(&i2c->dev, "%s: failed=%d\n", __func__, ret);
>>>        kfree(priv);
>>> -     return NULL;
>>> +     return ret;
>>>   }
>>> -EXPORT_SYMBOL(e4000_attach);
>>> +
>>> +static int e4000_remove(struct i2c_client *client)
>>> +{
>>> +     struct e4000_priv *priv = i2c_get_clientdata(client);
>>> +
>>> +     dev_dbg(&client->dev, "%s:\n", __func__);
>>> +
>>> +     kfree(priv);
>>> +     return 0;
>>> +}
>>> +
>>> +static const struct i2c_device_id e4000_id[] = {
>>> +     {"e4000", 0},
>>> +     {}
>>> +};
>>> +MODULE_DEVICE_TABLE(i2c, e4000_id);
>>> +
>>> +static struct i2c_driver e4000_driver = {
>>> +     .driver = {
>>> +             .owner  = THIS_MODULE,
>>> +             .name   = "e4000",
>>> +     },
>>> +     .probe          = e4000_probe,
>>> +     .remove         = e4000_remove,
>>> +     .id_table       = e4000_id,
>>> +};
>>> +
>>> +module_i2c_driver(e4000_driver);
>>>
>>>   MODULE_DESCRIPTION("Elonics E4000 silicon tuner driver");
>>>   MODULE_AUTHOR("Antti Palosaari <crope@iki.fi>");
>>> diff --git a/drivers/media/tuners/e4000.h b/drivers/media/tuners/e4000.h
>>> index 25ee7c0..760b206 100644
>>> --- a/drivers/media/tuners/e4000.h
>>> +++ b/drivers/media/tuners/e4000.h
>>> @@ -26,6 +26,11 @@
>>>
>>>   struct e4000_config {
>>>        /*
>>> +      * frontend
>>> +      */
>>> +     struct dvb_frontend *fe;
>>> +
>>> +     /*
>>>         * I2C address
>>>         * 0x64, 0x65, 0x66, 0x67
>>>         */
>>> @@ -39,10 +44,10 @@ struct e4000_config {
>>>
>>>   #if IS_ENABLED(CONFIG_MEDIA_TUNER_E4000)
>>
>> You can get rid of #if IS_ENABLED, by replacing it by a generic attach
>> function, using the subdev model. In other words, this is how a tuner
>> subdev is defined:
>>
>>          struct v4l2_subdev_tuner_ops {
>>                  int (*s_radio)(struct v4l2_subdev *sd);
>>                  int (*s_frequency)(struct v4l2_subdev *sd, const struct v4l2_frequency *freq);
>>                  int (*g_frequency)(struct v4l2_subdev *sd, struct v4l2_frequency *freq);
>>                  int (*g_tuner)(struct v4l2_subdev *sd, struct v4l2_tuner *vt);
>>                  int (*s_tuner)(struct v4l2_subdev *sd, const struct v4l2_tuner *vt);
>>                  int (*g_modulator)(struct v4l2_subdev *sd, struct v4l2_modulator *vm);
>>                  int (*s_modulator)(struct v4l2_subdev *sd, const struct v4l2_modulator *vm);
>>                  int (*s_type_addr)(struct v4l2_subdev *sd, struct tuner_setup *type);
>>                  int (*s_config)(struct v4l2_subdev *sd, const struct v4l2_priv_tun_config *config);
>>          };
>>
>> As the presence of the device is known, there's no need to actually attach
>> anything, but you need to pass the configuration for the subdevice. This is
>> done by calling the subdev s_config ops to setup them:
>>
>>          v4l2_subdev_call(sd, tuner, s_config, vfh, arg);
>>
>> A new callback will be needed there, in order to put the device into DVB mode,
>> e. g. passing the DVB specific parameters.
>>
>> As the subdev callbacks are defined on a generic .h header and they always
>> exist, if the driver is not compiled, i2c_new_device() won't find the driver,
>> and the bridge driver won't call s_config() for this I2C client.
>>
>> That's IMHO, one of the biggest advantages of this conversion: as a bonus,
>> we get rid of several Kconfig issues. Also, with this change, lsmod will
>> properly show that the tuner is bound to the bridge driver.
>>
>>>   extern struct dvb_frontend *e4000_attach(struct dvb_frontend *fe,
>>> -             struct i2c_adapter *i2c, const struct e4000_config *cfg);
>>> +             struct i2c_adapter *i2c, struct e4000_config *cfg);
>>>   #else
>>>   static inline struct dvb_frontend *e4000_attach(struct dvb_frontend *fe,
>>> -             struct i2c_adapter *i2c, const struct e4000_config *cfg)
>>> +             struct i2c_adapter *i2c, struct e4000_config *cfg)
>>>   {
>>>        dev_warn(&i2c->dev, "%s: driver disabled by Kconfig\n", __func__);
>>>        return NULL;
>>> diff --git a/drivers/media/tuners/e4000_priv.h b/drivers/media/tuners/e4000_priv.h
>>> index a385505..7f47068 100644
>>> --- a/drivers/media/tuners/e4000_priv.h
>>> +++ b/drivers/media/tuners/e4000_priv.h
>>> @@ -24,8 +24,10 @@
>>>   #include "e4000.h"
>>>
>>>   struct e4000_priv {
>>> -     const struct e4000_config *cfg;
>>>        struct i2c_adapter *i2c;
>>> +     struct i2c_client *i2c_client;
>>> +     u8 i2c_addr;
>>> +     u32 clock;
>>>   };
>>>
>>>   struct e4000_pll {
>>> diff --git a/drivers/media/usb/dvb-usb-v2/rtl28xxu.c b/drivers/media/usb/dvb-usb-v2/rtl28xxu.c
>>> index defc491..573805a 100644
>>> --- a/drivers/media/usb/dvb-usb-v2/rtl28xxu.c
>>> +++ b/drivers/media/usb/dvb-usb-v2/rtl28xxu.c
>>> @@ -843,11 +843,6 @@ err:
>>>        return ret;
>>>   }
>>>
>>> -static const struct e4000_config rtl2832u_e4000_config = {
>>> -     .i2c_addr = 0x64,
>>> -     .clock = 28800000,
>>> -};
>>> -
>>>   static const struct fc2580_config rtl2832u_fc2580_config = {
>>>        .i2c_addr = 0x56,
>>>        .clock = 16384000,
>>> @@ -874,10 +869,14 @@ static int rtl2832u_tuner_attach(struct dvb_usb_adapter *adap)
>>>        int ret;
>>>        struct dvb_usb_device *d = adap_to_d(adap);
>>>        struct rtl28xxu_priv *priv = d_to_priv(d);
>>> -     struct dvb_frontend *fe;
>>> +     struct dvb_frontend *fe = NULL;
>>> +     struct i2c_client *client = NULL;
>>> +     struct i2c_board_info info;
>>>
>>>        dev_dbg(&d->udev->dev, "%s:\n", __func__);
>>>
>>> +     memset(&info, 0, sizeof(struct i2c_board_info));
>>> +
>>>        switch (priv->tuner) {
>>>        case TUNER_RTL2832_FC0012:
>>>                fe = dvb_attach(fc0012_attach, adap->fe[0],
>>> @@ -897,9 +896,20 @@ static int rtl2832u_tuner_attach(struct dvb_usb_adapter *adap)
>>>                adap->fe[0]->ops.read_signal_strength =
>>>                                adap->fe[0]->ops.tuner_ops.get_rf_strength;
>>>                return 0;
>>> -     case TUNER_RTL2832_E4000:
>>> -             fe = dvb_attach(e4000_attach, adap->fe[0], &d->i2c_adap,
>>> -                             &rtl2832u_e4000_config);
>>> +     case TUNER_RTL2832_E4000: {
>>> +                     struct e4000_config e4000_config = {
>>> +                             .fe = adap->fe[0],
>>> +                             .i2c_addr = 0x64,
>>> +                             .clock = 28800000,
>>> +                     };
>>> +
>>> +                     strlcpy(info.type, "e4000", I2C_NAME_SIZE);
>>> +                     info.addr = 0x64;
>>> +                     info.platform_data = &e4000_config;
>>> +
>>> +                     request_module("e4000");
>>> +                     client = i2c_new_device(&d->i2c_adap, &info);
>>> +             }
>>>                break;
>>>        case TUNER_RTL2832_FC2580:
>>>                fe = dvb_attach(fc2580_attach, adap->fe[0], &d->i2c_adap,
>>> @@ -927,12 +937,11 @@ static int rtl2832u_tuner_attach(struct dvb_usb_adapter *adap)
>>>                                adap->fe[0]->ops.tuner_ops.get_rf_strength;
>>>                break;
>>>        default:
>>> -             fe = NULL;
>>>                dev_err(&d->udev->dev, "%s: unknown tuner=%d\n", KBUILD_MODNAME,
>>>                                priv->tuner);
>>>        }
>>>
>>> -     if (fe == NULL) {
>>> +     if (fe == NULL && (client == NULL || client->driver == NULL)) {
>>>                ret = -ENODEV;
>>>                goto err;
>>>        }
>>
>>
>> --
>>
>> Cheers,
>> Mauro
>> --
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