[PATCH] ath10k: fix system hang at qca99x0 probe on x86 platform

[Sebastian Gottschall]

from my point of view this patch is just shit. it trunkates the maximum 
allocated memory to a certain value.
so firmware requests 800 kb memory but just gets 256kb. so out of bound 
memory access is guaranteed at all.


Am 23.07.2016 um 00:43 schrieb Ben Greear:
> On 06/13/2016 11:17 PM, Rajkumar Manoharan wrote:
>> commit b057886524be ("ath10k: do not use coherent memory for allocated
>> device memory chunks") replaced coherent memory allocation for memory
>> chunks to fix low memory platforms. Unfortunately this is causing system
>> freeze on x86 platform while bringing up qca99x0 device. The system
>> hangs while DMA mapping bigger memory chunks (689816/865444 bytes). Fix
>> this by limiting maximum memory chunk size to 256 KiB per request.
>>
>> Cc: Felix Fietkau <nbd at nbd.name>
>> Fixes: b057886524be ("ath10k: do not use coherent memory for 
>> allocated device memory chunks")
>> Signed-off-by: Rajkumar Manoharan <rmanohar at qti.qualcomm.com>
>> ---
>>   drivers/net/wireless/ath/ath10k/wmi.c | 6 ++++++
>>   drivers/net/wireless/ath/ath10k/wmi.h | 1 +
>>   2 files changed, 7 insertions(+)
>>
>> diff --git a/drivers/net/wireless/ath/ath10k/wmi.c 
>> b/drivers/net/wireless/ath/ath10k/wmi.c
>> index 6279ab4a760e..7c15f65fe5ed 100644
>> --- a/drivers/net/wireless/ath/ath10k/wmi.c
>> +++ b/drivers/net/wireless/ath/ath10k/wmi.c
>> @@ -4411,6 +4411,12 @@ static int ath10k_wmi_alloc_chunk(struct 
>> ath10k *ar, u32 req_id,
>>           if (!pool_size)
>>               return -EINVAL;
>>
>> +        if (pool_size > WMI_MAX_MEM_CHUNK_SIZE) {
>> +            num_units = WMI_MAX_MEM_CHUNK_SIZE /
>> +                    round_up(unit_len, 4);
>> +            pool_size = num_units * round_up(unit_len, 4);
>> +        }
>
> I started testing my 9980 x86-64 system with VT/d enabled today.
> With this patch in my tree, it crashes on bootup (with my firmware).
> Works fine without this patch.
>
> I don't see the exact place it is crashing in the firmware, though I 
> could
> probably narrow it down with some effort.  It is in the early startup 
> code,
> at least, which makes debugging more difficult.
>
> This patch works fine with a slightly newer firmware compiled for 
> 9984.  That
> same firmware compiled for 9980 crashes, but I am not certain it is 
> the same issue
> as the older 9980.  It appears similar, at least.
>
> Looks to me like there are lots of variances in how firmware and chip 
> revisions
> deal with this particular code, so we are going to have to test on 
> lots of chips
> and platforms to know if a 'fix' is really a fix or not.
>
> Thanks,
> Ben
>
>


-- 
Mit freundlichen Grüssen / Regards

Sebastian Gottschall / CTO

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