Re: Wrongly identified easycap em28xx

["Frank Schäfer" <fschaefer.oss@googlemail.com>]

Am 19.02.2013 19:30, schrieb Mauro Carvalho Chehab:
> Em Tue, 19 Feb 2013 17:47:28 +0100
> Frank Schäfer <fschaefer.oss@googlemail.com> escreveu:
>
>> Am 18.02.2013 23:36, schrieb Mr Goldcove:
>>> I've only tried composite video input.
>>> The video/ audio output is good.
>>>  
>>> It has the following input:
>>> RCA stereo sound
>>> RCA video
>>> S-video
>>>
>>> It has no push button but has a green led which illuminates when the
>>> device is in use.
>>>
>>>
>>> On 18. feb. 2013 22:25, Frank Schäfer wrote:
>>>> Am 18.02.2013 21:53, schrieb Mr Goldcove:
>>>>> "Easy Cap DC-60++"
>>>>> Wrongly identified as card 19 "EM2860/SAA711X Reference Design",
>>>>> resulting in no audio.
>>>>> Works perfectly when using card 64 "Easy Cap Capture DC-60"
>>>> Video inputs work fine, right ?
>>>> Does this device has any buttons / LEDs ?
>>>>
>>>> The driver doesn't handle devices with generic IDs very well.
>>>> In this case we can conclude from the USB PID that the device has audio
>>>> support (which is actually the only difference to board
>>>> EM2860_BOARD_SAA711X_REFERENCE_DESIGN).
>>>> But I would like to think twice about it, because this kind of changes
>>>> has very a high potential to cause regressions for other boards...
>>>>
>>>> Regards,
>>>> Frank
>> After thinking about this for some minutes:
>> The easiest soulution would be, to add .amux = EM28XX_AMUX_LINE_IN lines
>> to input definitions of board EM2860_BOARD_SAA711X_REFERENCE_DESIGN.
>> No additional code lines (check for audio support etc.) would be needed
>> and (as side effect) board EM2860_BOARD_EASYCAP would become obsolete.
>>
>> The last modification of board EM2860_BOARD_SAA711X_REFERENCE_DESIGN was
>> commit 3ed58baf5db4eab553803916a990a3dbca4dc611 from Devin.
>> The commit message says
>>
>> "The device provides the audio through a pass-thru cable, so we don't need
>>  an actual audio capture profile (neither the K-World device nor the
>> Pointnix
>>  have an onboard audio decoder)"
>>
>> Changing the .amux settings doesn't cause any trouble for devices
>> without audio support
>> (there is actually no way to define _no_ amux, without this line in the
>> input definition .amux is 0 = EM28XX_AMUX_VIDEO).
>>
>> BUT: as we are talking about devices with generic USB IDs, we don't (and
>> will never) know about all other existing devices.
>> There _might_ be some unknown devices with audio support, which are
>> working silently with the current audio settings for board
>> EM2860_BOARD_SAA711X_REFERENCE_DESIGN.
>>
>> OTOH: if we keep the two separate boards and switch from board
>> EM2860_BOARD_SAA711X_REFERENCE_DESIGN to board EM2860_BOARD_EASYCAP when
>> the device has audio support,
>> the same shit can happen.
>>
>> Thoughts ?
>>
>> Does anyone know how the Empia-driver handles devices with generic IDs ?
>> Do you think we can assume their driver uses a single reference board
>> design for the detected combination of USB-ID and subdevices ?
>>
> I don't like the idea of merging those two entries. As far as I remember
> there are devices that works out of the box with
> EM2860_BOARD_SAA711X_REFERENCE_DESIGN. A change like that can break
> the driver for them.

As described above, there is a good chance to break devices with both
solutions.

What's your suggestion ? ;-)

Regards,
Frank


> Regards,
> Mauro