What methods are available to enable zero-copy support on smartphones with Qualcomm GPUs?

I have tried various methods. First, I confirmed the presence of Unified Memory through CL_DEVICE_HOST_UNIFIED_MEMORY and CL_DEVICE_GLOBAL_MEM_CACHE_TYPE. However, after testing the following example, I found that there is no automatic synchronization unless I actively call enqueueReadBuffer to update.The result is “Zero Copy Supported: No” This is the incomprehensible part. Shouldn’t the GPU on mobile phones all support zero-copy?

#include <CL/cl.hpp>
#include <vector>
#include <iostream>

int main() {
    const int dataSize = 1024;
    std::vector<int> data(dataSize, 1); 

    cl::Platform platform;
    cl::Device device;
    cl::Context context;
    cl::CommandQueue queue;
    cl::Buffer buffer;

    try {
        std::vector<cl::Platform> platforms;
        cl::Platform::get(&platforms);
        platform = platforms[0];
        std::vector<cl::Device> devices;
        platform.getDevices(CL_DEVICE_TYPE_GPU, &devices);
        device = devices[0];
        context = cl::Context({device});
        queue = cl::CommandQueue(context, device);

        buffer = cl::Buffer(context, CL_MEM_READ_WRITE | CL_MEM_USE_HOST_PTR, sizeof(int) * dataSize, data.data());

        const char* kernelSource = R"CLC(
        __kernel void modify_data(__global int* data) {
            int id = get_global_id(0);
            data[id] *= 2; 
        }
        )CLC";

        cl::Program::Sources sources;
        sources.push_back({kernelSource, strlen(kernelSource)});
        cl::Program program(context, sources);
        program.build({device});
        cl::Kernel kernel(program, "modify_data");

        kernel.setArg(0, buffer);
        queue.enqueueNDRangeKernel(kernel, cl::NullRange, cl::NDRange(dataSize), cl::NullRange);
        queue.finish();

        bool zeroCopy = true;
        for (int i = 0; i < dataSize; ++i) {
            if (data[i] != 2) {
                zeroCopy = false;
                break;
            }
        }

        std::cout << "Zero Copy Supported: " << (zeroCopy ? "Yes" : "No") << std::endl;

    } catch (cl::Error& err) {
        std::cerr << "OpenCL Error: " << err.what() << " (" << err.err() << ")" << std::endl;
        return -1;
    }

    return 0;
}