msync with MS_SYNC option failure

Autonomous Machines Jetson & Embedded Systems Jetson TX1
#1

Does Linux on TX1 not support MS_SYNC option for msync?

I mmaped hardware buffer to memory and modified the contents of the memory.
I had to use sleep for about two seconds before the change is written back.
To avoid using sleep, I thought using msync with MS_SYNC is the desired effect I was looking for

But when I try to do so, msync returns EINVAL.

I’d appreciate any comments or advices.
Thanks.

#2

Hi devnglee, I’ll take a look and then get back to you.

#3

Hi devnglee, Could you share your sample code?

#4

Hi vickyy,

I’m trying to capture an image via libargus and process the captured data.

int dmabuf_fd = iImageNativeBuffer->createNvBuffer(
        Size {WIDTH, HEIGHT}, NvBufferColorFormat_YUV420, NvBufferLayout_Pitch);
NvBufferParams params;
NvBufferGetParams(dmabuf_fd, &params);

size_t fsize = params.pitch[0] * params.height[0];

uint8_t* data_mem = (uint8_t*)mmap(
        0, fsize, PROT_READ | PROT_WRITE, MAP_SHARED, dmabuf_fd, params.offset[0]);

/*               ...                */
/* Read and modify data at data_mem */
/*               ...                */

msync(data_mem, fsize, MS_SYNC);            /* EINVAL */
#5

The next BSP release will have below functions in nvbuf_utils.h for this.

NvBufferMemMap
NvBufferMemSyncForCpu
NvBufferMemSyncForDevice
NvBufferMemUnMap

If still have any question, please let me know.

#6

Are there any samples demonstrating use of these functions?

#7

Looks like you have found it :p https://devtalk.nvidia.com/default/topic/1026106/jetson-tx1/usage-of-nvbuffer-apis/post/5224382/#5224382