IMX8MP: OpenCL extension 'cl_khr_external_memory_dma_buf' missing?

[pete_sensoray]

I need to use the OpenCL extension 'cl_khr_external_memory_dma_buf' for processing a video buffer using zero-copy, but the extension isn't listed in the string returned from CL_DEVICE_EXTENSIONS:

CL_DEVICE_NAME: Vivante OpenCL Device GC7000UL.6204.0000
CL_DEVICE_VENDOR: Vivante Corporation
CL_DRIVER_VERSION: OpenCL 3.0 V6.4.11.p2.745085
CL_DEVICE_PROFILE: FULL_PROFILE
CL_DEVICE_VERSION: OpenCL 3.0 
CL_DEVICE_EXTENSIONS: cl_khr_byte_addressable_store cl_khr_fp16 cl_khr_il_program cl_khr_global_int32_base_atomics cl_khr_global_int32_extended_atomics cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics cl_khr_icd cl_khr_command_buffer 

UG10159 says should be supported with this SW version 6.4.11, which is what appears in the driver version.

Any suggestions?

[joanxie]

I checked the cl_ext.h under the /usr/include/CL, this extension already exists, I attached the header file 

/***************************************************************
* cl_khr_external_memory_dma_buf
***************************************************************/
#define cl_khr_external_memory_dma_buf 1

/* cl_external_memory_handle_type_khr */
#define CL_EXTERNAL_MEMORY_HANDLE_DMA_BUF_KHR 0x2067

[pete_sensoray]

Sorry, that's not how extension detection works. The presence of the extension in the driver is not indicated by the cl_ext.h header file -- all possible extensions are listed there and detection happens during program execution.  An extension is supported when it is returned in the string from the glGetDeviceInfo function call:

char extensions[1024];
clGetDeviceInfo(device, CL_DEVICE_EXTENSIONS, sizeof(extensions), extensions, NULL);
printf("CL_DEVICE_EXTENSIONS: %s\n", extensions);
if (strstr(extensions, "cl_khr_external_memory_dma_buf") == NULL) {
// Handle error: DMA-BUF extension not supported
}

Either the documentation is wrong, or the extensions list in the driver is wrong.

[joanxie · Accepted solution]

confirmed that imx8mp can support this, suggest customer to call the driver directly, to check if the return value is correct or not, don't need to check this print information

[pete_sensoray]

Thanks for following up.  It does appear to work.  For anyone else trying to do this, this is how the buffer is created:

cl_mem_properties extMemProperties[] =
{
	CL_EXTERNAL_MEMORY_HANDLE_DMA_BUF_KHR, (cl_mem_properties)buf->dma_fd,
	0
};
cl_mem buffer_YUYV = clCreateBufferWithProperties(
	/*context*/          context,
	/*properties*/       extMemProperties,
	/*flags*/            CL_MEM_READ_ONLY,
	/*size*/             buf->size,
	/*host_ptr*/         NULL,
	/*errcode_ret*/      &err);