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

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?
I'm not familiar with those abbreviations.

Thanks,
Timur