Re: [PATCH] ts2020: call get_rf_strength from frontend

[Antti Palosaari <crope@iki.fi>]

On 01/06/2013 08:14 PM, Malcolm Priestley wrote:
> On Sun, 2013-01-06 at 15:37 +0200, Antti Palosaari wrote:
>> On 01/06/2013 02:40 PM, Malcolm Priestley wrote:
>>> Restore ds3000.c read_signal_strength.
>>>
>>> Call tuner get_rf_strength from frontend read_signal_strength.
>>>
>>> We are able to do a NULL check and doesn't limit the tuner
>>> attach to the frontend attach area.
>>>
>>> At the moment the lmedm04 tuner attach is stuck in frontend
>>> attach area.
>>
>> I would like to nack that, as I see some problems:
>> 1) it changes deviation against normal procedures
>> 2) interface driver (usb/pci) should have full control to make decision
>> 3) you shoot to our own leg easily in power management
>>
> This patch does not do any operational changes, and is a proper way to
> call to another module with a run time NULL check. The same way as
> another tuner function from demodulator is called.

uh, certainly I understand it does not change functionality in that 
case! I tried to point out it is logically insane and error proof. Ee 
should make this kind of direct calls between drivers as less as 
possible - just to make life easier in future. It could work for you, 
but for some other it could cause problems as hardware is designed 
differently.

>> * actually bug 3) already happened some drivers, like rtl28xxu. Tuner is
>> behind demod and demod is put sleep => no access to tuner. FE callback
>> is overridden (just like you are trying to do as default) which means
>> user-space could still make queries => I/O errors.
>
> In such cases, the tuner init/sleep should also be called.

???????
I think you don't understand functionality at all!

See that bug report, I was referring
http://permalink.gmane.org/gmane.linux.drivers.video-input-infrastructure/48216

It is not long time I added checks to DVB-core to avoid it calling 
statistics IOCTLs if frontend is not active.

But simply, it is situation your demod driver should not make decision 
whether statistics are asked from the tuner or not. It is decision that 
should be left to interface driver. It is single line of code to 
override that logic in interface driver - or add even some other logic 
how to perform measurement and in which condition. Interface driver is 
driver which knows best power-management etc. related stuff.


Antti



>
>
> Regards
>
>
> Malcolm
>
>
>> Antti
>>
>>
>>>
>>> Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
>>> ---
>>>    drivers/media/dvb-frontends/ds3000.c    | 10 ++++++++++
>>>    drivers/media/dvb-frontends/m88rs2000.c |  4 +++-
>>>    drivers/media/dvb-frontends/ts2020.c    |  1 -
>>>    3 files changed, 13 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/media/dvb-frontends/ds3000.c b/drivers/media/dvb-frontends/ds3000.c
>>> index d128f85..1e344b0 100644
>>> --- a/drivers/media/dvb-frontends/ds3000.c
>>> +++ b/drivers/media/dvb-frontends/ds3000.c
>>> @@ -533,6 +533,15 @@ static int ds3000_read_ber(struct dvb_frontend *fe, u32* ber)
>>>    	return 0;
>>>    }
>>>
>>> +static int ds3000_read_signal_strength(struct dvb_frontend *fe,
>>> +						u16 *signal_strength)
>>> +{
>>> +	if (fe->ops.tuner_ops.get_rf_strength)
>>> +		fe->ops.tuner_ops.get_rf_strength(fe, signal_strength);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>>    /* calculate DS3000 snr value in dB */
>>>    static int ds3000_read_snr(struct dvb_frontend *fe, u16 *snr)
>>>    {
>>> @@ -1102,6 +1111,7 @@ static struct dvb_frontend_ops ds3000_ops = {
>>>    	.i2c_gate_ctrl = ds3000_i2c_gate_ctrl,
>>>    	.read_status = ds3000_read_status,
>>>    	.read_ber = ds3000_read_ber,
>>> +	.read_signal_strength = ds3000_read_signal_strength,
>>>    	.read_snr = ds3000_read_snr,
>>>    	.read_ucblocks = ds3000_read_ucblocks,
>>>    	.set_voltage = ds3000_set_voltage,
>>> diff --git a/drivers/media/dvb-frontends/m88rs2000.c b/drivers/media/dvb-frontends/m88rs2000.c
>>> index 283c90f..4da5272 100644
>>> --- a/drivers/media/dvb-frontends/m88rs2000.c
>>> +++ b/drivers/media/dvb-frontends/m88rs2000.c
>>> @@ -446,7 +446,9 @@ static int m88rs2000_read_ber(struct dvb_frontend *fe, u32 *ber)
>>>    static int m88rs2000_read_signal_strength(struct dvb_frontend *fe,
>>>    	u16 *strength)
>>>    {
>>> -	*strength = 0;
>>> +	if (fe->ops.tuner_ops.get_rf_strength)
>>> +		fe->ops.tuner_ops.get_rf_strength(fe, strength);
>>> +
>>>    	return 0;
>>>    }
>>>
>>> diff --git a/drivers/media/dvb-frontends/ts2020.c b/drivers/media/dvb-frontends/ts2020.c
>>> index f50e237..ad7ad85 100644
>>> --- a/drivers/media/dvb-frontends/ts2020.c
>>> +++ b/drivers/media/dvb-frontends/ts2020.c
>>> @@ -363,7 +363,6 @@ struct dvb_frontend *ts2020_attach(struct dvb_frontend *fe,
>>>
>>>    	memcpy(&fe->ops.tuner_ops, &ts2020_tuner_ops,
>>>    				sizeof(struct dvb_tuner_ops));
>>> -	fe->ops.read_signal_strength = fe->ops.tuner_ops.get_rf_strength;
>>>
>>>    	return fe;
>>>    }
>>>
>>
>>
>
>


-- 
http://palosaari.fi/