Re: [PATCH] tda10071: make sure both tuner and demod i2c addresses are specified

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On Tue, Jan 1, 2013 at 10:39 AM, Antti Palosaari <crope@xxxxxx> wrote:
> On 12/17/2012 03:12 AM, Michael Krufky wrote:
>>
>> display an error message if either tuner_i2c_addr or demod_i2c_addr
>> are not specified in the tda10071_config structure
>
>
> Nack.
>
> I don't see it necessary at all to check correctness of driver configuration
> values explicitly like that. Those are values which user cannot never change
> and when driver developer pass wrong values he will find it out very soon as
> hardware is not working.
>
> Adding comments to configuration struct which says possible values is
> advisable and enough IMHO.
>
> Maybe you should open own topic for discussion if you really would like to
> add this kind of checks. It is not tda10071 driver specific change, it
> affects about all drivers.


Antti,

I don't believe that your NACK has any technical merit- we are trying
to enforce good programming practice here, and when we find that a
piece of silicon has a configurable option, we like to expose that
option.  We try not to make default values unless its necessary, but
when there are differing i2c addresses, it is always best to have that
listed explicitly in the configuration structures.  It's called
self-documenting code- It's the way we try to write code in the Linux
kernel.

In this case, there was one previous user of the tda10071 driver and
it was a small change to add both tuner and demod i2c addresses to the
configuration structure.

We did speak about this on IRC on the sixteenth of December, and you
seemed OK with the idea:

[18:21] <mkrufky> dunno if you saw i asked earlier, but.... if you
want to review the patches, i can include your credentials on the pull
request
[18:21] <mkrufky> tda10071 patch:
http://git.linuxtv.org/mkrufky/hauppauge.git/commitdiff/4244d8155324263df37a8b2e067e7b9b81faec29
[18:22] <mkrufky> cx23885 patch:
http://git.linuxtv.org/mkrufky/hauppauge.git/commitdiff/eb658993b7a834911a3e8aabc7729b2505eef7d0
[18:22] <mkrufky> and i'll add another patch error out if the
tuner_i2c_addr is not specified, as devin recommended
[18:22] <mkrufky> (and also change the other tda10071 user to specify
0x14 for tuner_i2c_addr)
[18:23] <crope> Acked-by: Antti Palosaari <crope@xxxxxx>
[18:23] <crope> Reviewed-by: Antti Palosaari <crope@xxxxxx>
[18:23] <mkrufky> cool, thanks :-)
[18:24] <crope> I think 14 is the default, it is hard to understand
why ever one wants to use some other address in case of it is
controlled by demod :] but feel free to do that
[18:24] <mkrufky> ok
[18:25] <mkrufky> thats why i'll do it in a separate patch -- no need
to confuse a board addition with other cleanups
[18:25] <crope> eg cx24116/cx24118 does not specify tuner address at
all (as far as I see) => I think it is hard coded even to firmware
[18:26] <mkrufky> yea ur right

...the tuner and demod addresses can be changed, so we represent that
in the configuration structure.  I see no reason why you should have
any complaints about this patch.

Best regards,

Mike


> regards
> Antti
>
>
>
>>
>> Signed-off-by: Michael Krufky <mkrufky@xxxxxxxxxxx>
>> ---
>>   drivers/media/dvb-frontends/tda10071.c  |   18 +++++++++++++++---
>>   drivers/media/dvb-frontends/tda10071.h  |    4 ++--
>>   drivers/media/pci/cx23885/cx23885-dvb.c |    2 +-
>>   drivers/media/usb/em28xx/em28xx-dvb.c   |    3 ++-
>>   4 files changed, 20 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/media/dvb-frontends/tda10071.c
>> b/drivers/media/dvb-frontends/tda10071.c
>> index 7103629..02f9234 100644
>> --- a/drivers/media/dvb-frontends/tda10071.c
>> +++ b/drivers/media/dvb-frontends/tda10071.c
>> @@ -30,7 +30,7 @@ static int tda10071_wr_regs(struct tda10071_priv *priv,
>> u8 reg, u8 *val,
>>         u8 buf[len+1];
>>         struct i2c_msg msg[1] = {
>>                 {
>> -                       .addr = priv->cfg.i2c_address,
>> +                       .addr = priv->cfg.demod_i2c_addr,
>>                         .flags = 0,
>>                         .len = sizeof(buf),
>>                         .buf = buf,
>> @@ -59,12 +59,12 @@ static int tda10071_rd_regs(struct tda10071_priv
>> *priv, u8 reg, u8 *val,
>>         u8 buf[len];
>>         struct i2c_msg msg[2] = {
>>                 {
>> -                       .addr = priv->cfg.i2c_address,
>> +                       .addr = priv->cfg.demod_i2c_addr,
>>                         .flags = 0,
>>                         .len = 1,
>>                         .buf = &reg,
>>                 }, {
>> -                       .addr = priv->cfg.i2c_address,
>> +                       .addr = priv->cfg.demod_i2c_addr,
>>                         .flags = I2C_M_RD,
>>                         .len = sizeof(buf),
>>                         .buf = buf,
>> @@ -1202,6 +1202,18 @@ struct dvb_frontend *tda10071_attach(const struct
>> tda10071_config *config,
>>                 goto error;
>>         }
>>
>> +       /* make sure demod i2c address is specified */
>> +       if (!config->demod_i2c_addr) {
>> +               dev_dbg(&i2c->dev, "%s: invalid demod i2c address!\n",
>> __func__);
>> +               goto error;
>> +       }
>> +
>> +       /* make sure tuner i2c address is specified */
>> +       if (!config->tuner_i2c_addr) {
>> +               dev_dbg(&i2c->dev, "%s: invalid tuner i2c address!\n",
>> __func__);
>> +               goto error;
>> +       }
>> +
>>         /* setup the priv */
>>         priv->i2c = i2c;
>>         memcpy(&priv->cfg, config, sizeof(struct tda10071_config));
>> diff --git a/drivers/media/dvb-frontends/tda10071.h
>> b/drivers/media/dvb-frontends/tda10071.h
>> index a20d5c4..bff1c38 100644
>> --- a/drivers/media/dvb-frontends/tda10071.h
>> +++ b/drivers/media/dvb-frontends/tda10071.h
>> @@ -28,10 +28,10 @@ struct tda10071_config {
>>          * Default: none, must set
>>          * Values: 0x55,
>>          */
>> -       u8 i2c_address;
>> +       u8 demod_i2c_addr;
>>
>>         /* Tuner I2C address.
>> -        * Default: 0x14
>> +        * Default: none, must set
>>          * Values: 0x14, 0x54, ...
>>          */
>>         u8 tuner_i2c_addr;
>> diff --git a/drivers/media/pci/cx23885/cx23885-dvb.c
>> b/drivers/media/pci/cx23885/cx23885-dvb.c
>> index cf84c53..a1aae56 100644
>> --- a/drivers/media/pci/cx23885/cx23885-dvb.c
>> +++ b/drivers/media/pci/cx23885/cx23885-dvb.c
>> @@ -662,7 +662,7 @@ static struct mt2063_config terratec_mt2063_config[] =
>> {
>>   };
>>
>>   static const struct tda10071_config hauppauge_tda10071_config = {
>> -       .i2c_address = 0x05,
>> +       .demod_i2c_addr = 0x05,
>>         .tuner_i2c_addr = 0x54,
>>         .i2c_wr_max = 64,
>>         .ts_mode = TDA10071_TS_SERIAL,
>> diff --git a/drivers/media/usb/em28xx/em28xx-dvb.c
>> b/drivers/media/usb/em28xx/em28xx-dvb.c
>> index 63f2e70..e800881 100644
>> --- a/drivers/media/usb/em28xx/em28xx-dvb.c
>> +++ b/drivers/media/usb/em28xx/em28xx-dvb.c
>> @@ -714,7 +714,8 @@ static struct tda18271_config
>> em28xx_cxd2820r_tda18271_config = {
>>   };
>>
>>   static const struct tda10071_config em28xx_tda10071_config = {
>> -       .i2c_address = 0x55, /* (0xaa >> 1) */
>> +       .demod_i2c_addr = 0x55, /* (0xaa >> 1) */
>> +       .tuner_i2c_addr = 0x14,
>>         .i2c_wr_max = 64,
>>         .ts_mode = TDA10071_TS_SERIAL,
>>         .spec_inv = 0,
>>
>
>
> --
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