Document the Conv2D heuristic

- Add a new section in the documentation to describe how the conv2D
heuristic works on Arm® Cortex®-based CPUs and Arm® Mali™-based GPUs
- Add CKW_UNUSED in compute_kernel_writer/src/cl/CLTile.cpp to avoid
the compilation error due to an unused variable
- Remove FFT from the list of algorithms to be selected by the CPU Conv2d
heuristic.

Resolves COMPMID-6163

Signed-off-by: Gian Marco Iodice <gianmarco.iodice@arm.com>
Change-Id: I51384d7749451b2562642683e8b2429a355166bb
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/10065
Benchmark: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Jakub Sujak <jakub.sujak@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>

1 files changed, 1 insertions, 5 deletions

diff --git a/src/cpu/operators/CpuConv2d.cpp b/src/cpu/operators/CpuConv2d.cpp
index fa8a7a185c..447b740989 100644
--- a/src/cpu/operators/CpuConv2d.cpp
+++ b/src/cpu/operators/CpuConv2d.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2021 Arm Limited.
+ * Copyright (c) 2017-2021, 2023 Arm Limited.
  *
  * SPDX-License-Identifier: MIT
  *
@@ -178,10 +178,6 @@ ConvolutionMethod CpuConv2d::get_convolution_method(const ITensorInfo *input, co
         {
             return ConvolutionMethod::DIRECT;
         }
-        if((weights->dimension(idx_h) > 7) && (input->dimension(idx_c) > output->dimension(idx_c)) && (NEFFTConvolutionLayer::validate(input, weights, nullptr, output, conv_info, act_info)))
-        {
-            return ConvolutionMethod::FFT;
-        }
         if(input->dimension(idx_c) < 16)
         {
             return ConvolutionMethod::GEMM;