RE: [RFC] Stand-alone Resizer/Previewer Driver support under V4L2 framework

From: Hiremath, Vaibhav <hidden>
Date: 2009-04-20 10:47:37
Also in: linux-omap


Thanks,
Vaibhav Hiremath

-----Original Message-----
From: Dongsoo, Nathaniel Kim [mailto:dongsoo.kim@gmail.com]
Sent: Monday, April 20, 2009 4:15 PM
To: Hiremath, Vaibhav
Cc: Hans Verkuil; linux-media@vger.kernel.org; Aguirre Rodriguez,
Sergio Alberto; Toivonen Tuukka.O (Nokia-D/Oulu); linux-
omap@vger.kernel.org; Nagalla, Hari; Sakari Ailus; Jadav, Brijesh R;
R, Sivaraj; Hadli, Manjunath; Shah, Hardik; Kumar, Purushotam
Subject: Re: [RFC] Stand-alone Resizer/Previewer Driver support
under V4L2 framework

Hello Vaibhav,

This is user manual of S3C6400 (not much different from S3C6410)
http://www.ebv.com/fileadmin/products/Products/Samsung/S3C6400/S3C64
00X_UserManual_rev1-0_2008-02_661558um.pdf

That SoC is from my company but not from the same division of mine.
Actually I'm doing this driver job without any request from chip
delivering division. I'm doing this because this is so challenging
and
want better generic driver :-)

Take a look at the user manual and please let me know your opinion.
In my understanding scaler and some camera interface feature in
S3C64XX are very similar to the features in Omap3.

[Hiremath, Vaibhav] Thanks for the link, I will go though it and get back to you.

Cheers,

Nate

On Mon, Apr 20, 2009 at 7:11 PM, Hiremath, Vaibhav [off-list ref]
wrote:

quoted


Thanks,
Vaibhav Hiremath

quoted

-----Original Message-----
From: linux-media-owner@vger.kernel.org [mailto:linux-media-
owner@vger.kernel.org] On Behalf Of Dongsoo Kim
Sent: Sunday, April 19, 2009 12:06 PM
To: Hans Verkuil
Cc: Hiremath, Vaibhav; linux-media@vger.kernel.org; Aguirre
Rodriguez, Sergio Alberto; Toivonen Tuukka.O (Nokia-D/Oulu);

linux-

quoted

omap@vger.kernel.org; Nagalla, Hari; Sakari Ailus; Jadav, Brijesh

R;

quoted

R, Sivaraj; Hadli, Manjunath; Shah, Hardik; Kumar, Purushotam
Subject: Re: [RFC] Stand-alone Resizer/Previewer Driver support
under V4L2 framework

Hello Hans and Hiremath,

One of my recent job is making S3C64XX camera interface driver

(even

quoted

though other jobs of mine are not finished yet...;-()
And, what a incident! S3C64XX has also similar H/W block in

camera

quoted

interface.
Resizer in S3C camera interface can be used in system wide like

the

quoted

one in Omap3.

[Hiremath, Vaibhav] Can you share the spec for the same; I wanted

to verify the configuration part of it? What all configuration is
exported to the user?

quoted

But in case of mine, I decided to make it as a TYPE_VIDEO_CAPTURE
and
TYPE_VIDEO_OUTPUT.
I thought that is was enough. Actually I took omap video out

(vout?)

quoted

for reference :-)

[Hiremath, Vaibhav] I have also implemented the driver is the same

way and also working with Hans to get it reviewed. But there are
some configuration like coeff., luma enhancement, etc... need to
export to the user, where we need to add mechanism in V4L2
framework.

quoted

Since we have one more device where we are demanding for M-to-M

operation, I think it is important to go through it. Can you share
some documents of your IP for better understanding.

quoted

Cheers,

Nate


2009. 04. 19, 오전 12:53, Hans Verkuil 작성:

quoted

On Tuesday 31 March 2009 10:53:02 Hiremath, Vaibhav wrote:

quoted

Thanks,
Vaibhav Hiremath

quoted

APPROACH 3 -
----------

.....

(Any other approach which I could not think of would be

appreciated)

quoted

I would prefer second approach, since this will provide

standard

quoted

interface to applications independent on underneath

hardware.

quoted

There may be many number of such configuration parameters

required

quoted

for

quoted

different such devices, we need to work on this and come up

with

quoted

some

quoted

standard capability fields covering most of available

devices.

quoted

Does anybody have some other opinions on this?
Any suggestions will be helpful here,

FYI: I have very little time to look at this for the next 2-3

weeks.

quoted

As you
know I'm working on the last pieces of the v4l2_subdev

conversion

quoted

for 2.6.30
that should be finished this week. After that I'm attending

the

quoted

Embedded
Linux Conference in San Francisco.

But I always thought that something like this would be just a
regular video
device that can do both 'output' and 'capture'. For a resizer

quoted

would
expect that you set the 'output' size (the size of your

source

quoted

image) and
the 'capture' size (the size of the resized image), then just

send

quoted

the
frames to the device (== resizer) and get them back on the

capture

quoted

side.

[Hiremath, Vaibhav] Yes, it is possible to do that.

Hans,

I went through the link referred by Sergio and I think we

should

quoted

inherit
some implementation for CODECs here for such devices.

V4L2_BUF_TYPE_CODECIN - To access the input format.
V4L2_BUF_TYPE_CODECOUT - To access the output format.

It makes sense, since such memory-to-memory devices will

mostly

quoted

being

quoted

used from codecs context. And this would be more clear from

user

quoted

application.

To be honest, I don't see the need for this. I think
TYPE_VIDEO_CAPTURE and
TYPE_VIDEO_OUTPUT are perfectly fine.

quoted

And as acknowledged by you, we can use VIDIOC_S_FMT for

setting

quoted

parameters.

One thing I am not able to convince myself is that, using

"priv"

quoted

field
for custom configuration.

I agree. Especially since you cannot use it as a pointer to

addition

quoted

information.

quoted

I would prefer and recommend capability based
interface, where application will query the capability of the
device for
luma enhancement, filter coefficients (number of coeff and

depth),

quoted

interpolation type, etc...

This way we can make sure that, any such future devices can be
adapted by
this framework.

The big question is how many of these capabilities are

'generic'

quoted

and

quoted

how
many are very much hardware specific. I am leaning towards

using

quoted

the

quoted

extended control API for this. It's a bit awkward to implement

in

quoted

drivers
at the moment, but that should improve in the future when a lot

of

quoted

the

quoted

control handling code will move into the new core framework.

I really need to know more about the sort of features that

omap/

quoted

davinci
offer (and preferably also for similar devices by other
manufacturers).

quoted


Hans,
Have you get a chance to look at Video-Buf layer issues I

mentioned

quoted

in
original draft?

I've asked Magnus Damm to take a look at this. I know he did

some

quoted

work in
this area and he may have fixed some of these issues already.

Very

quoted

useful,
that Embedded Linux conference...

Regards,

    Hans

--
Hans Verkuil - video4linux developer - sponsored by TANDBERG

=
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



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info.html

quoted



--
========================================================
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
========================================================

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