topic Re: dma_alloc_coherent error for mipi csi2 camera in i.MX Processors

dma_alloc_coherent error for mipi csi2 camera

srinivasaporam — Thu, 07 Jan 2016 10:03:53 GMT

Hi,

We have got imx6Q customized board designed based on reference board (Wandboard).

Custom board is having 512 MB RAM (LPDDR2) where as reference board has got 2GB DDR3 RAM.

We have connected MIPI CSI2 interface and when we are running the following command:

$ sudo avconv -f video4linux2 -s 640x480 -i /dev/video0 -ss 0:0:2 -frames 1 /tmp/out.jpg

we are getting the following error:

ERROR: v4l2 capture: VIDIOC_REQBUFS: not enough buffers
ERROR: v4l2 capture: mxc_allocate_frame_buf failed.

When i searched for the same in my kernel source got the place where this error will be coming

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

static int mxc_allocate_frame_buf(cam_data *cam, int count)

{

int i;

pr_debug("In MVC:mxc_allocate_frame_buf - size=%d\n",

cam->v2f.fmt.pix.sizeimage);

for (i = 0; i < count; i++) {

cam->frame[i].vaddress =

dma_alloc_coherent(0,

PAGE_ALIGN(cam->v2f.fmt.pix.sizeimage),

&cam->frame[i].paddress,

GFP_DMA | GFP_KERNEL);

if (cam->frame[i].vaddress == 0) {

pr_err("ERROR: v4l2 capture: "

"mxc_allocate_frame_buf failed.\n");

mxc_free_frame_buf(cam);

return -ENOBUFS;

}

cam->frame[i].buffer.index = i;

cam->frame[i].buffer.flags = V4L2_BUF_FLAG_MAPPED;

cam->frame[i].buffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

cam->frame[i].buffer.length =

PAGE_ALIGN(cam->v2f.fmt.pix.sizeimage);

cam->frame[i].buffer.memory = V4L2_MEMORY_MMAP;

cam->frame[i].buffer.m.offset = cam->frame[i].paddress;

cam->frame[i].index = i;

}

return 0;

}

so, why dma_alloc_coherent is returning 0 which is being assigned to cam->frame[i].vaddress.

How to resolve this issue???

Re: dma_alloc_coherent error for mipi csi2 camera

Yuri — Mon, 11 Jan 2016 09:12:30 GMT

Hello,

Perhaps the system has no enough memory for operations.

The following may be helpful

imx53 video DMA memory fragmentation

Have a great day,
Yuri

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Re: dma_alloc_coherent error for mipi csi2 camera

srinivasaporam — Tue, 12 Jan 2016 13:35:10 GMT

Hi,

I tried the instructions (echo 1 > /proc/sys/vm/lowmem_reserve_ratio) but , still the problem is there. may be iam not using instruction correctly.

Re: dma_alloc_coherent error for mipi csi2 camera

srinivasaporam — Tue, 12 Jan 2016 13:37:23 GMT

And also,

We think this is not the issue because of memory. Because there are the boards , with 512 MB RAM (like imx6sl evk, Wandboard solo etc)

are there any other mistakes that we are doing... outr board is imx6D, with LPDDR2 (512MB).

Re: dma_alloc_coherent error for mipi csi2 camera

Yuri — Tue, 02 Feb 2016 08:19:47 GMT

Hello,

strictly speaking i.MX6SL EVK has 1 GB LPDDR2.

Regards,

Yuri.