[PATCH kernel v3 0/3] powerpc/ioda2: Yet another attempt to allow DMA masks between 32 and 59

[Alexey Kardashevskiy]

On 18/06/2019 14:26, Shawn Anastasio wrote:
> On 6/12/19 2:15 PM, Shawn Anastasio wrote:
>> On 6/12/19 2:07 AM, Alexey Kardashevskiy wrote:
>>>
>>>
>>> On 12/06/2019 15:05, Shawn Anastasio wrote:
>>>> On 6/5/19 11:11 PM, Shawn Anastasio wrote:
>>>>> On 5/30/19 2:03 AM, Alexey Kardashevskiy wrote:
>>>>>> This is an attempt to allow DMA masks between 32..59 which are not
>>>>>> large
>>>>>> enough to use either a PHB3 bypass mode or a sketchy bypass.
>>>>>> Depending
>>>>>> on the max order, up to 40 is usually available.
>>>>>>
>>>>>>
>>>>>> This is based on v5.2-rc2.
>>>>>>
>>>>>> Please comment. Thanks.
>>>>>
>>>>> I have tested this patch set with an AMD GPU that's limited to <64bit
>>>>> DMA (I believe it's 40 or 42 bit). It successfully allows the card to
>>>>> operate without falling back to 32-bit DMA mode as it does without
>>>>> the patches.
>>>>>
>>>>> Relevant kernel log message:
>>>>> ```
>>>>> [    0.311211] pci 0033:01     : [PE# 00] Enabling 64-bit DMA bypass
>>>>> ```
>>>>>
>>>>> Tested-by: Shawn Anastasio <shawn at anastas.io>
>>>>
>>>> After a few days of further testing, I've started to run into stability
>>>> issues with the patch applied and used with an AMD GPU. Specifically,
>>>> the system sometimes spontaneously crashes. Not just EEH errors either,
>>>> the whole system shuts down in what looks like a checkstop.
>>>>
>>>> Perhaps some subtle corruption is occurring?
>>>
>>> Have you tried this?
>>>
>>> https://patchwork.ozlabs.org/patch/1113506/
>>
>> I have not. I'll give it a shot and try it out for a few days to see
>> if I'm able to reproduce the crashes.
> 
> A few days later and I was able to reproduce the checkstop while
> watching a video in mpv. At this point the system had ~4 day
> uptime and this wasn't the first video I watched during that time.
> 
> This is with https://patchwork.ozlabs.org/patch/1113506/ applied, too.


Any logs left? What was the reason for the checkstop and what is the
hardware? "lscpu" and "lspci -vv" for the starter would help. Thanks,


-- 
Alexey