Re: amdgpu driver fails to initialize on ppc64le in 7.0-rc1 and newer

[Gaurav Batra <gbatra@linux.ibm.com>]

Thanks a lot Dan for testing Ritesh's patch.

@Ritesh, I need to test the 2 scenarios for which I sent the first patch,

Thanks,

Gaurav

On 3/26/26 5:38 AM, Ritesh Harjani (IBM) wrote:
> Dan Horák <dan@danny.cz> writes:
>
>> Hi Ritesh,
>>
>> On Wed, 25 Mar 2026 23:12:16 +0530
>> Ritesh Harjani (IBM) <ritesh.list@gmail.com> wrote:
>>
>>> Gaurav Batra <gbatra@linux.ibm.com> writes:
>>>
>>>> Hello Ritesh
>>>>
>>>> I think, what you are proposing to add dev->bus_dma_limit in the check
>>>> might work. In the case of PowerNV, this is not set, but
>>>> dev->dma_ops_bypass is set. So, for PowerNV, it will fall back to how it
>>>> was before.
>>>>
>>>> Also, since these both are set in LPAR mode, the current patch as-is
>>>> will work.
>>>>
>>>> Dan, can you please try Ritesh proposed fix on your PowerNV box? I am
>>>> not able to lay my hands on a PowerNV box yet.
>>>>
>>> It would be this diff then. Note, I have only compile tested it.
>>>
>>> diff --git a/arch/powerpc/kernel/dma-iommu.c b/arch/powerpc/kernel/dma-iommu.c
>>> index 73e10bd4d56d..8b4de508d2eb 100644
>>> --- a/arch/powerpc/kernel/dma-iommu.c
>>> +++ b/arch/powerpc/kernel/dma-iommu.c
>>> @@ -67,7 +67,7 @@ bool arch_dma_unmap_sg_direct(struct device *dev, struct scatterlist *sg,
>>>   }
>>>   bool arch_dma_alloc_direct(struct device *dev)
>>>   {
>>> -       if (dev->dma_ops_bypass)
>>> +       if (dev->dma_ops_bypass && dev->bus_dma_limit)
>>>                  return true;
>>>
>>>          return false;
>>> @@ -75,7 +75,7 @@ bool arch_dma_alloc_direct(struct device *dev)
>>>
>>>   bool arch_dma_free_direct(struct device *dev, dma_addr_t dma_handle)
>>>   {
>>> -       if (!dev->dma_ops_bypass)
>>> +       if (!dev->dma_ops_bypass || !dev->bus_dma_limit)
>>>                  return false;
>>>
>>>          return is_direct_handle(dev, dma_handle);
>> this seems to fix the amdgpu initialization, full kernel log available
>> as https://fedora.danny.cz/tmp/kernel-7.0-rc5.log
>>
>> Tested-by: Dan Horák <dan@danny.cz>
>>
> Thanks a lot Dan!
>
> @Gaurav,
> In that case, please feel free to take the diff and submit an official
> patch (if you think this looks good for all cases). You might want to
> test your previous usecase once, so that we don't see any new surprises
> there :)
>
> -ritesh