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

[Rajkumar Manoharan]

On 2016-06-02 22:57, Ben Greear wrote:
> 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...
> 
Yeah.. But the code should work even on non-VT-d systems. ins't it?
> 
> 
>> 
>> 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>
>> 
>> 
Ben,

Can you help to confirm this issue by disabling VT-d and bring up 
qca99x0? If it freezes, try reverting the patch.

-Rajkumar