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

[Alexey Kardashevskiy]

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/



-- 
Alexey