About s_stream in v4l2-subdev

About s_stream in v4l2-subdev

[Dongsoo, Nathaniel Kim]

Hello everyone,

I'm doing my driver job with kernel 2.6.30-rc6, trying to figure out
how to convert my old drivers to v4l2-subdev framework. Looking into
the v4l2-subdev.h file an interesting API popped up and can't find any
precise comment about that. It is "s_stream" in v4l2_subdev_video_ops.
I think I found this api in the very nick of time, if the purpose of
that api  is exactly what I need. Actually, I was trying to make my
sub device to get streamon and streamoff command from the device side,
and I wish the "s_stream" is that for. Because in case of camera
module with embedded JPEG encoder, it is necessary to make the camera
module be aware of the exact moment of streamon to pass the encoded
data to camera interface. (many of camera ISPs can't stream out
continuous frame of JPEG data, so we have only one chance  of shot).
Is the s_stream for streamon purpose in subdev? (I hope so...finger crossed)
Cheers,

Nate

-- 
=
DongSoo, Nathaniel Kim
Engineer
Mobile S/W Platform Lab.
Digital Media & Communications R&D Centre
Samsung Electronics CO., LTD.
e-mail : dongsoo.kim@gmail.com
          dongsoo45.kim@samsung.com

Re: About s_stream in v4l2-subdev

[Hans Verkuil]

On Thursday 28 May 2009 13:20:15 Dongsoo, Nathaniel Kim wrote:
> Hello everyone,
>
> I'm doing my driver job with kernel 2.6.30-rc6, trying to figure out
> how to convert my old drivers to v4l2-subdev framework. Looking into
> the v4l2-subdev.h file an interesting API popped up and can't find any
> precise comment about that. It is "s_stream" in v4l2_subdev_video_ops.
> I think I found this api in the very nick of time, if the purpose of
> that api  is exactly what I need. Actually, I was trying to make my
> sub device to get streamon and streamoff command from the device side,
> and I wish the "s_stream" is that for. Because in case of camera
> module with embedded JPEG encoder, it is necessary to make the camera
> module be aware of the exact moment of streamon to pass the encoded
> data to camera interface. (many of camera ISPs can't stream out
> continuous frame of JPEG data, so we have only one chance  of shot).
> Is the s_stream for streamon purpose in subdev? (I hope so...finger
> crossed) Cheers,

Yes it is. It is for subdevs that need to implement VIDIOC_STREAMON and 
VIDIOC_STREAMOFF.

Regards,

	Hans


-- 
Hans Verkuil - video4linux developer - sponsored by TANDBERG Telecom

Re: About s_stream in v4l2-subdev

[Dongsoo, Nathaniel Kim]

Thank you Hans,
Regards,

Nate

On Fri, May 29, 2009 at 6:21 AM, Hans Verkuil <hverkuil@xs4all.nl> wrote:
> On Thursday 28 May 2009 13:20:15 Dongsoo, Nathaniel Kim wrote:
>> Hello everyone,
>>
>> I'm doing my driver job with kernel 2.6.30-rc6, trying to figure out
>> how to convert my old drivers to v4l2-subdev framework. Looking into
>> the v4l2-subdev.h file an interesting API popped up and can't find any
>> precise comment about that. It is "s_stream" in v4l2_subdev_video_ops.
>> I think I found this api in the very nick of time, if the purpose of
>> that api  is exactly what I need. Actually, I was trying to make my
>> sub device to get streamon and streamoff command from the device side,
>> and I wish the "s_stream" is that for. Because in case of camera
>> module with embedded JPEG encoder, it is necessary to make the camera
>> module be aware of the exact moment of streamon to pass the encoded
>> data to camera interface. (many of camera ISPs can't stream out
>> continuous frame of JPEG data, so we have only one chance  of shot).
>> Is the s_stream for streamon purpose in subdev? (I hope so...finger
>> crossed) Cheers,
>
> Yes it is. It is for subdevs that need to implement VIDIOC_STREAMON and
> VIDIOC_STREAMOFF.
>
> Regards,
>
>        Hans
>
>
> --
> Hans Verkuil - video4linux developer - sponsored by TANDBERG Telecom
>



-- 
=
DongSoo, Nathaniel Kim
Engineer
Mobile S/W Platform Lab.
Digital Media & Communications R&D Centre
Samsung Electronics CO., LTD.
e-mail : dongsoo.kim@gmail.com
          dongsoo45.kim@samsung.com