Regression in qca99x0 on x86 platform (kernel: 4.7.0-rc1-wt-ath

[Manoharan, Rajkumar]

Found a regression in ath.git TOT that system hangs while probing qca99x0 device on x86_64 platform.
It seems the system hangs while DMA mapping of bigger memory chunks. Below are the list of memory
chucks requested by target for qca99x0 during service ready event. This issue is seen only on x86 platform.
No issues are observed on ARM platform (AP148). After reverting below commit able to bring up device on x86.

Jun  2 17:24:37 rmanohar-arch kernel: idx 0 pool_size 689816 num_units 529 unit_len 1304
Jun  2 17:24:37 rmanohar-arch kernel: idx 1 pool_size 17152 num_units 67 unit_len 256
Jun  2 17:24:37 rmanohar-arch kernel: idx 2 pool_size 68608 num_units 67 unit_len 1024
Jun  2 17:24:37 rmanohar-arch kernel: idx 3 pool_size 274432 num_units 67 unit_len 4096
Jun  2 17:24:37 rmanohar-arch kernel: idx 4 pool_size 107520 num_units 35 unit_len 3072
Jun  2 17:24:37 rmanohar-arch kernel: idx 5 pool_size 6144 num_units 1 unit_len 6144
Jun  2 17:24:37 rmanohar-arch kernel: idx 6 pool_size 865444 num_units 529 unit_len 1636

commit b057886524be060021e3cfad0ba8458c850330cd
Author: Felix Fietkau <nbd at openwrt.org>
Date:   Mon Nov 30 19:32:01 2015 +0100

    ath10k: do not use coherent memory for allocated device memory chunks
    
    Coherent memory is more expensive to allocate (and constrained on some
    architectures where it has to be pre-allocated). It is also completely
    unnecessary, since the host has no reason to even access these allocated
    memory spaces
    
    Signed-off-by: Felix Fietkau <nbd at openwrt.org>
    Signed-off-by: Kalle Valo <kvalo at qca.qualcomm.com>

-Rajkumar