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Subject: Re: [PATCH,v4] Revert "ath10k: fix DMA related firmware crashes on
 multiple devices"
To:     Zhi Chen <zhichen@codeaurora.org>
Cc:     ath10k@lists.infradead.org, linux-wireless@vger.kernel.org
References: <1578976521-6104-1-git-send-email-zhichen@codeaurora.org>
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From:   Ben Greear <greearb@candelatech.com>
Organization: Candela Technologies
Message-ID: <9389929a-cd65-6ed8-3a17-2826ef7b0a2f@candelatech.com>
Date:   Tue, 8 Sep 2020 21:02:25 -0700
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Please see this bug report, and feel free to ask the reporter for more details if you
don't find everything you need there.  Seems a basic ping test reproduces packet loss
in their case...

  https://github.com/greearb/ath10k-ct/issues/153

I don't actually have the platform in question.

Thanks,
Ben

On 9/8/20 7:04 PM, Zhi Chen wrote:
> Hi Ben,
>    Thanks for your information. The DMA issue is host related. We never hit this issue with X86 platform. And it was only seen in stress cases with 50+ 
> STAs(association and disassociation repeatedly). What's the host platform you are using? And how was the issue reproduced?
> 
> Thanks,
> Zhi
> 
> On 2020-09-09 01:48, Ben Greear wrote:
>> Hello,
>>
>> Just FYI:  I added this patch to my ath10k-ct driver, and a user
>> reported it causes
>> regressions on his particular 9888 system when using ath10k-ct wave-2 firmware:
>>
>> [   21.204868] ath10k_pci 0000:00:00.0: qca9888 hw2.0 target
>> 0x01000000 chip_id 0x00000000 sub 0000:0000
>> [   21.214437] ath10k_pci 0000:00:00.0: kconfig debug 0 debugfs 1
>> tracing 0 dfs 1 testmode 0
>> [   21.233298] ath10k_pci 0000:00:00.0: firmware ver
>> 10.4b-ct-9888-tH-13-8c5b2baa2 api 5 features
>> mfp,peer-flow-ctrl,txstatus-noack,wmi-10.x-CT,ratemask-CT,regdump-CT,txrate-CT,flush-all-CT,pingpong-CT,ch-regs-CT,nop-CT,htt-mgt-CT,set-special-CT,no-bmiss-CT,tx-rc-CT,cust-stats-CT,txrate2-CT,beacon-cb-CT,wmi-block-ack-CT,wmi-bcn-rc-CT 
>>
>> crc32 a00b5f36
>> [   21.596684] ath10k_pci 0000:00:00.0: board_file api 2 bmi_id 0:20
>> crc32 5bb32c02[   23.546156] ath10k_pci 0000:00:00.0: unsupported HTC
>> service id: 1536
>>
>> I'll revert this for the 9888 chipset (at least) in my driver,
>> possibly you need to do similar.
>>
>> https://github.com/greearb/ath10k-ct/issues/153
>>
>> Thanks,
>> Ben
>>
>> On 1/13/20 8:35 PM, Zhi Chen wrote:
>>> This reverts commit 76d164f582150fd0259ec0fcbc485470bcd8033e.
>>> PCIe hung issue was observed on multiple platforms. The issue was reproduced
>>> when DUT was configured as AP and associated with 50+ STAs.
>>>
>>> For QCA9984/QCA9888, the DMA_BURST_SIZE register controls the AXI burst size
>>> of the RD/WR access to the HOST MEM.
>>> 0 - No split , RAW read/write transfer size from MAC is put out on bus
>>>      as burst length
>>> 1 - Split at 256 byte boundary
>>> 2,3 - Reserved
>>>
>>> With PCIe protocol analyzer, we can see DMA Read crossing 4KB boundary when
>>> issue happened. It broke PCIe spec and caused PCIe stuck. So revert
>>> the default value from 0 to 1.
>>>
>>> Tested:  IPQ8064 + QCA9984 with firmware 10.4-3.10-00047
>>>           QCS404 + QCA9984 with firmware 10.4-3.9.0.2--00044
>>>           Synaptics AS370 + QCA9888  with firmware 10.4-3.9.0.2--00040
>>>
>>> Signed-off-by: Zhi Chen <zhichen@codeaurora.org>
>>> ---
>>> v2: restored 10.2 register configuration
>>> v3: modified commit message
>>> v4: resolved conflicts
>>> ---
>>>   drivers/net/wireless/ath/ath10k/hw.h | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/net/wireless/ath/ath10k/hw.h b/drivers/net/wireless/ath/ath10k/hw.h
>>> index 21b7a2a..775fd62 100644
>>> --- a/drivers/net/wireless/ath/ath10k/hw.h
>>> +++ b/drivers/net/wireless/ath/ath10k/hw.h
>>> @@ -816,7 +816,7 @@ ath10k_is_rssi_enable(struct ath10k_hw_params *hw,
>>>     #define TARGET_10_4_TX_DBG_LOG_SIZE        1024
>>>   #define TARGET_10_4_NUM_WDS_ENTRIES        32
>>> -#define TARGET_10_4_DMA_BURST_SIZE        0
>>> +#define TARGET_10_4_DMA_BURST_SIZE        1
>>>   #define TARGET_10_4_MAC_AGGR_DELIM        0
>>>   #define TARGET_10_4_RX_SKIP_DEFRAG_TIMEOUT_DUP_DETECTION_CHECK 1
>>>   #define TARGET_10_4_VOW_CONFIG            0
>>>
> 


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