"Jon Arne Jørgensen" <jona...@jonarne.no> wrote:

>On Mon, May 20, 2013 at 06:33:20AM -0400, Andy Walls wrote:
>> "Jon Arne Jørgensen" <jona...@jonarne.no> wrote:
>> 
>> >Hi,
>> >I've recently discovered that the smi2021 device have some pretty
>> >specific
>> >needs for the setup of the gm7113c chip.
>> >
>> >Both the smi2021 driver and the stk1160 driver needs registers
>> >0x14 -> 0x17 to be zeroed, this is what forced me to add the gm7113c
>> >chip to the saa7115 driver in the first place.
>> >
>> >Then Timo reported that the Terratec Grabby hwrev2 needs some of the
>> >initial register settings to be changed for the device to work.
>> >He posted a small list of required changes.
>> >One of these changes is a change to register 0x12 which sets
>> >up what to output on the RTS0 pin on the chip.
>> >
>> >Then I discovered that the smi2021 needs the V-Flag in the SAV/EAV
>> >to be generated by VREF - whatever that means :).
>> >That is, I need bit 7 to be clear and bit 6 to be set in register
>0x10.
>> >To have the device behave correctly.
>> >
>> >Both the change for the smi2021 driver and the changes for the
>Terratec
>> >device are pretty hardware specific.
>> >They should probably not be part of the generic gm7113c setup.
>> >
>> >I would also guess that if other devices with the gm7113c chip
>should
>> >surface, these devices might also have different needs for the setup
>of
>> >the chip.
>> >
>> >I'm not sure what would be the correct way to handle these
>> >differences.
>> >The only sollution I'we tried is to bypass the saa7115
>> >driver, and push the needed changes directly over usb to the device,
>> >after the initial setup is sent by the saa7115 driver.
>> >This is a major hack, and the changes should probably go through
>> >the saa7115 driver.
>> >
>> >Should the saa7115 driver be extended with an interface to change
>> >random
>> >register settings, or does the i2c subsystem already have a way to
>> >handle this?
>> >
>> >Any idea about what might could be a better sollution?
>> >
>> >Best regards
>> >Jon Arne Jørgensen
>> >
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>> 
>> For v4l2_subdev's there is a way to pass in platform/bridge device
>specific data so initialization can be different than the default,
>based on the needs of the bridge driver.
>
>Ok, can you give any pointers to any documentation/source files I can
>look at for this?
>
>> 
>> As for the meaning of the V (Vertical) flag in Start Active Video
>(SAV) / End Active Video (EAV) markers, the VESA VIP 1.x standard
>explains that.  Basically they are codes embedded in digitized video
>rasters horizontal blanking interval that describe the current video
>line and delimit their start and end.
>> 
>> The V flag probably means a line in the vertical blanking interval
>(VBI), but I can't recall.
>> 
>
>I'm sorry, I was a bit quick with that comment.
>I know what the SAV/EAV and V-flag is. I just don't know what it means
>that the V-flag is
>generated by VREF.
>
>> Regards,
>> Andy
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http://lxr.free-electrons.com/source/drivers/media/i2c/wm8775.c#L232

The bttv driver, IIRC, has the wm8775 driver initialize differently for the 
Nova S card.  FWIW, the defaults for the wm8775 driver are generally those 
needed by the ivtv driver.

Regards,
Andy
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