topic How to print the camera frame buffer? in i.MX Processors

How to print the camera frame buffer?

titusstalin — Wed, 30 Nov 2016 12:22:35 GMT

Dear All,

Can you please tell me how to print the content of camera frame buffer ?

Want to print the camera frame buffer in kernel driver for debugging purposes.

May be need to add some code in below code, don't know how to access.

drivers/media/platform/mxc/capture/mxc_v4l2_capture.c

Thanks for your support.

Regards,

Titus S.

Re: How to print the camera frame buffer?

rogerio_silva — Wed, 30 Nov 2016 12:56:31 GMT

Hi Titus,

You can check this user application example:

v4l2-examples/example2.c at master · rogeriorps/v4l2-examples · GitHub

It's based on /unit_tests/mxc_v4l2_tvin.out

On lines 397 and 399 it makes a memcopy to copy the image between input and output buffers. The camera buffer is available at "capture_buffers[capture_buf.index].start" in this example.

Best regards,

Rogerio

Re: How to print the camera frame buffer?

titusstalin — Wed, 30 Nov 2016 14:50:47 GMT

Thanks.

But I'm able to do this already in userspace.

I want to do it in kernel driver.

Can you please help me on this ?

Regards,

Titus S.

Re: How to print the camera frame buffer?

rogerio_silva — Wed, 30 Nov 2016 15:07:50 GMT

Supposing you're using an i.MX with IPU, in kernel drivers, the starting address of framebuffers are registered on EBA0 (and in case of double buffer also in EBA1) registers inside each IDMAC CPMEM Parameters. I think it will be easier to work on IPU drivers instead V4L2. They're located at linix/drivers/mxc/ipu3/.

Re: How to print the camera frame buffer?

titusstalin — Wed, 30 Nov 2016 17:40:37 GMT

Thanks Rogerio.

I'm able to print the contents of frame buffer.

char *pTmp = (char *) cam->frame[0].vaddress;
printk("\n ####################### Titus Start 0x%x 0x%x ####################\n",buf->m.offset,cam->frame[0].vaddress);
   for(i=0;i<100;i++)
   {
   printk(" i -> %d, 0x%x ",i,*pTmp++);
   }

Re: How to print the camera frame buffer?

rogerio_silva — Wed, 30 Nov 2016 18:14:57 GMT

Very good! Thanks for the feedback.

Rogerio