DM3730 Display rotation

Thushara Jayakumar

Other Parts Discussed in Thread: DM3730

Hi,

Im working on DM3730. I am displaying using ioctl calls to v4l2 display driver. But there is a resolution setting problem that some portion of my video is not able to see in the lcd display. I tried to do rotate by adding the following code snippet in my application

ctrl.id = V4L2_CID_ROTATE;
ctrl.value = 90;
if (ioctl(v4l2fd, VIDIOC_S_CTRL, &ctrl) < 0)
{
printf("set ctrl rotate failed\n");
exit(0);
}"

With this setting my query buffer API VIDIOC_REQBUFS is failing. Im getting page allocation error.

Please suggest me some method by which I can resolve this issue.

Thanks in advance

Thushara Jayakumar.

over 9 years ago

0 Cvetolin Shulev-XID over 9 years ago

TI__Guru 65405 points

Hi Thushara,

The posted code fragment for display rotation seems correct but according the Linux TV documentation it is necessary to set the new height and width of the picture using the VIDIOC_S_FMT ioctl according to the rotation angle selected. In your case (rotation on 90 degrees) will be necessary to reverse the height and width of the display window.

I suggest you to check the setting of resolution and image format negotiation. For some details you can refer to the documentation of the Linux media infrastructure API at the link:

http://linuxtv.org/downloads/v4l-dvb-apis/index.html

Also you can check whether the following patch presents in your sources:

https://patchwork.linuxtv.org/patch/15193/

Tsvetolin Shulev

0 Thushara Jayakumar over 9 years ago in reply to Cvetolin Shulev-XID

Intellectual 585 points

Hi Shulev,

I am doing the setting as u suggested for width and height after swapping. But the page allocation error is still there.

It would be helpful also to know how we can change the lcd display resolution.

Thanks

Thushara.

0 Cvetolin Shulev-XID over 9 years ago in reply to Thushara Jayakumar

TI__Guru 65405 points

Hi Thushara,

Resolution change is possible after stopping all V4L2 display and fbdev nodes connected to a particular display where you want resolution change. You can view the PSP VPSS Video Driver User Guide for some additional details at the link:

http://processors.wiki.ti.com/index.php/TI81XX_PSP_VPSS_Video_Driver_User_Guide

Tsvetolin Shulev

0 Thushara Jayakumar over 9 years ago in reply to Cvetolin Shulev-XID

Intellectual 585 points

Hi Shulev,

I was able to set the resolution as 1280x720

I am using bootargs:

setenv bootargs 'console=ttyO0,115200n8 root=/dev/mmcblk0p2 rw ip=off mem=68M@0x80000000 rootwait omapfb.mode=dvi:1280x720@60'

for changing resolution.It seems to have set the value as "cat /sys/devices/platform/omapdss/display2/timings" gives me "72434,1280/120/190/32,720/3/13/5".

But still my 800x480 video is out of bound. Some portion s still not visible.

Im not able to get the exact problem. Please guide me to sort out this issue.

Regards

Thushara.

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DM3730 Display rotation