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

[Shawn Anastasio]

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.