• opencv 3.4.15
• centos 7.9, kernel 5.13.5-1 with i915.force_probe=4c8a
• gcc 7.3.1
• CPU: i5-11600
• intel-opencl-21.28.20343-1.el7.x86_64

At the runtime of an opencv application which use the ocl4dnn module, a lot of 'simd size' errors are generated, like these ones:

OpenCV(ocl4dnn): The OpenCL compiler chose a simd size (16) that does not equal the size (8) kernel source required.
Skip this kernel U_GEMM_LIKE_CONV_k3x3_cn3_g1_s2x2_d1x1_b1_in256x256_p1x1_num1_M32_activ1_eltwise0_FP32_5_1_8_32_SIMD8
OpenCV(ocl4dnn): The OpenCL compiler chose a simd size (32) that does not equal the size (16) kernel source required.
Skip this kernel IDLF_k3x3_cn3_g1_s2x2_d1x1_b1_in256x256_p1x1_num1_M32_activ1_eltwise0_FP32_2_7_3_1_SIMD16

If the CPU is replaced with an i5-10600, without changing anything else, the errors disappear and the GPU code runs without any issue at all.