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

[Ben Greear]

On 06/02/2016 10:20 AM, Manoharan, Rajkumar wrote:
> 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

We have seen similar.  But, if we enable VT-d in our BIOS, then it works, at least in
our scenarios.  I have not tried putting more than one 99x0 NIC in a system to date, so possibly
more than one would cause more issues, and I guess systems without VT-d might
fail too...

Thanks,
Ben


>
> 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
> _______________________________________________
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>


-- 
Ben Greear <greearb at candelatech.com>
Candela Technologies Inc  http://www.candelatech.com