Re: [PATCH 11/14] drm/amdgpu/ih6.0: Use MMIO ACK for retry CAM on IH 6.0

["Lazar, Lijo" <lijo.lazar@amd.com>]

On 16-Jul-26 4:25 AM, Timur Kristóf wrote:
> On Tuesday, July 7, 2026 10:25:09 AM Central European Summer Time Lazar, Lijo
> wrote:
>> On 04-Jul-26 12:20 AM, Timur Kristóf wrote:
>>> On 2026. július 3., péntek 20:11:59 közép-európai nyári idő Joshi, Mukul
>>>
>>> wrote:
>>>>> I still haven't found any explanation why we use a doorbell for the CAM
>>>>> in
>>>>> the first
>>>>
>>>> place? Lijo, Alex, Felix does anybody know that?
>>>>
>>>>
>>>> If I remember correctly, we weren't sure if the IH_RETRY_CAM_ACK register
>>>> would be available under
>>>> virtualization. And we were sure doorbells would
>>>> work for both bare-metal and virtualization.
>>>
>>> Hi Mukul,
>>>
>>> Can you clarify that please?
>>>
>>> How are retry faults supposed to work under virtualization? Is the
>>> interrupt processed by the guest or the host? Why is the IH_RETRY_CAM_ACK
>>> register not available under virtualization?
>>
>> For clarification - CAM entries are separate for PF/VF. ACK register
>> also has PF/VF copies. However, in general host driver imposes MMIO
>> register access restrictions to VF, possibly that's the reason.
>>
>> Please note that IH_RETRY_INT_CAM_CNTL is PF only. With new versions,
>> please make sure to add a VF check for programming.
> 
> Hi Lijo,
> 
> Can you please clarify what PF and VF means here?

PF = physical function.  VF = virtual function. On virtualization 
environments amdgpu is a guest driver.

Translates to below check for cam_cntl register programming.
	if (!amdgpu_sriov_vf(adev))

Thanks,
Lijo

> I'm not familiar with those abbreviations.
> 
> Thanks,
> Timur
> 
>