Re: About Rcar Du

Re: About Rcar Du

[Laurent Pinchart]

Hello Stuvart,

On Thursday 19 Jan 2017 08:24:38 Stuvart S wrote:
> Hi Laurent and all,
>     I would like to ask a very basic question here .. I have an Rcar E2
> board with me..Linux 4.8 version kernel is running perfectly on this
> board.. Now I am getting videos on HDMI output.. I would like to modify
> this video by tapping from du unit and rescale that video .. I found that
> many du output source code are there in driver/gpu/drm/rcar-du ..I dont
> know which of these that I have to edit.. Am I able to take video/ image
> data from du? I am a newbi in this field ..

The DU doesn't have any scaler, you will need to use an external scaler, such 
as the one included in the VSP (using OpenGL for scaling is also an option if 
you have support for the GPU). No kernel modification is needed for this, the 
DU and VSP are both supported in mainline with a DRM/KMS and V4L2 driver 
respectively.

-- 
Regards,

Laurent Pinchart

Re: About Rcar Du

[Laurent Pinchart]

Hello Stuvart,

On Thursday 19 Jan 2017 09:43:16 Stuvart S wrote:
> On Thu, Jan 19, 2017 at 2:44 PM Laurent Pinchart wrote:
> > On Thursday 19 Jan 2017 08:24:38 Stuvart S wrote:
> >> Hi Laurent and all,
> >> 
> >> I would like to ask a very basic question here .. I have an Rcar E2
> >> board with me..Linux 4.8 version kernel is running perfectly on this
> >> board.. Now I am getting videos on HDMI output.. I would like to modify
> >> this video by tapping from du unit and rescale that video .. I found
> >> that many du output source code are there in driver/gpu/drm/rcar-du ..I
> >> dont know which of these that I have to edit.. Am I able to take video/
> >> image data from du? I am a newbi in this field ..
> > 
> > The DU doesn't have any scaler, you will need to use an external scaler,
> > such as the one included in the VSP (using OpenGL for scaling is also an
> > option if you have support for the GPU). No kernel modification is needed
> > for this, the DU and VSP are both supported in mainline with a DRM/KMS and
> > V4L2 driver respectively.
> 
> Thank you so much . I understand.. But here I am trying to ask about data
> tapping from DU .. I cant see any data flow through DU source code ..which
> area that I have to focus to do so.. Normally many DU outputs are there
> like lvds,hdmi etc.. Here I would like to try to take the data at just
> before output port

Do you mean capturing the frames to memory ? The DU supports write-back, but 
there's no software support for it on R-Car Gen2 at the moment.

> I dont know wether it is a meaningless question ..

-- 
Regards,

Laurent Pinchart

Re: About Rcar Du

[Stuvart S]

Hi Laurent,

     Thank you for that information. I am not meaning to capture the
frames to memory but, I have my own C code snippet to alter image to
some other forms which reads from a frame buffer ..here I am going to
do the tapping of image data from DU and modify according to my code
and write back to same location so that I expect the DU output will
alter..Actually there should be the image data which is get transfered
through DU unit to various DU outputs right?

or should I Concentrate on framebuffer?...I Could see a file named
framebuffer.c in /driver/gpu/drm/ in the stable kernel release which I
Could not in older versions..I don't know what is the reason of that..

Regards,
Stuvart

On 19 January 2017 at 18:12, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
> Hello Stuvart,
>
> On Thursday 19 Jan 2017 09:43:16 Stuvart S wrote:
>> On Thu, Jan 19, 2017 at 2:44 PM Laurent Pinchart wrote:
>> > On Thursday 19 Jan 2017 08:24:38 Stuvart S wrote:
>> >> Hi Laurent and all,
>> >>
>> >> I would like to ask a very basic question here .. I have an Rcar E2
>> >> board with me..Linux 4.8 version kernel is running perfectly on this
>> >> board.. Now I am getting videos on HDMI output.. I would like to modify
>> >> this video by tapping from du unit and rescale that video .. I found
>> >> that many du output source code are there in driver/gpu/drm/rcar-du ..I
>> >> dont know which of these that I have to edit.. Am I able to take video/
>> >> image data from du? I am a newbi in this field ..
>> >
>> > The DU doesn't have any scaler, you will need to use an external scaler,
>> > such as the one included in the VSP (using OpenGL for scaling is also an
>> > option if you have support for the GPU). No kernel modification is needed
>> > for this, the DU and VSP are both supported in mainline with a DRM/KMS and
>> > V4L2 driver respectively.
>>
>> Thank you so much . I understand.. But here I am trying to ask about data
>> tapping from DU .. I cant see any data flow through DU source code ..which
>> area that I have to focus to do so.. Normally many DU outputs are there
>> like lvds,hdmi etc.. Here I would like to try to take the data at just
>> before output port
>
> Do you mean capturing the frames to memory ? The DU supports write-back, but
> there's no software support for it on R-Car Gen2 at the moment.
>
>> I dont know wether it is a meaningless question ..
>
> --
> Regards,
>
> Laurent Pinchart
>



-- 
                        --- Come    Let's enjoy the world of Open Source  ---


Best regards,
Stuvart

Re: About Rcar Du

[Laurent Pinchart]

Hellu Stuvart,

On Thursday 19 Jan 2017 23:06:08 Stuvart S wrote:
> Hi Laurent,
> 
> Thank you for that information. I am not meaning to capture the
> frames to memory but, I have my own C code snippet to alter image to
> some other forms which reads from a frame buffer ..here I am going to
> do the tapping of image data from DU and modify according to my code
> and write back to same location so that I expect the DU output will
> alter..Actually there should be the image data which is get transfered
> through DU unit to various DU outputs right?
> 
> or should I Concentrate on framebuffer?...I Could see a file named
> framebuffer.c in /driver/gpu/drm/ in the stable kernel release which I
> Could not in older versions..I don't know what is the reason of that..

I think you need to learn more about the DRM/KMS API. At this point this isn't 
a DU-specific issue, and what you want to do isn't how the display APIs in 
Linux operate.

-- 
Regards,

Laurent Pinchart