On 08/01/2011 03:46 AM, Mauro Carvalho Chehab wrote:
> Em 27-07-2011 16:49, Antti Palosaari escreveu:
>> On 07/27/2011 10:06 PM, Mauro Carvalho Chehab wrote:
>>
>>>> + for (i = 0; i<= x; i++) {
>>>> + ret = adap->props.frontend_attach(adap);
>>>> + if (ret || adap->fe[i] == NULL) {
>>>> + /* only print error when there is no FE at all */
>>>> + if (i == 0)
>>>> + err("no frontend was attached by '%s'",
>>>> + adap->dev->desc->name);
>>>
>>> This doesn't seem right. One thing is to accept adap->fe[1] to be
>>> NULL. Another thing is to accept an error at the attach. IMO, the
>>> logic should be something like:
>>>
>>> if (ret< 0)
>>> return ret;
>>>
>>> if (!i&& !adap->fe[0]) {
>>> err("no adapter!");
>>> return -ENODEV;
>>> }
>>
>> Heh, I tried to keep it functioning as earlier not to break anything! Only
>> thing it does now differently is that it keeps silent when 2nd FE attach
>> fails since we don't know always before fe attach if there is fe or not.
>>
>> So since it *does not change old behaviour* it must be OK. Let fix old
>> problems later. There is millions of DVB USB callbacks failing silently -
>> like tuner_attach etc.
>>
>> Surely I want also fix many old issues but it is always too risky.
>
> Added support for DRX-K way at dvb-usb:
>
> http://git.linuxtv.org/mchehab/experimental.git/commitdiff/765b3db218f1e9af6432251c2ebe59bc9660cd42
> http://git.linuxtv.org/mchehab/experimental.git/commitdiff/37fa5797c58068cc60cca6829bd662cd4f883cfa
>
> One bad thing I noticed with the API is that it calls
> adap->props.frontend_attach(adap)
> several times, instead of just one, without even passing an argument for the
> driver to
> know that it was called twice.
>
> IMO, there are two ways of doing the attach:
>
> 1) call it only once, and, inside the driver, it will loop to add the other
> FE's;
> 2) add a parameter, at the call, to say what FE needs to be initialized.
>
> I think (1) is preferred, as it is more flexible, allowing the driver to test
> for
> several types of frontends.
For more you add configuration parameters more it goes complex. Now it
calls attach as many times as .num_frontends is set in adapter
configuration. It is currently only DRX-K frontend which does not behave
like other FEs. You have added similar hacks to em28xx and now DVB USB.
Maybe it could be easier to change DRX-K driver to attach and register
as others. Also I see it very easy at least in theory to register as one
DRX-K FE normally and then hack 2nd FE in device driver (which is I
think done other drivers using that chip too).
regards
Antti
--
http://palosaari.fi/
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