Re: [PATCH v2 2/7] media: iris: switch to hardware mode after firmware boot

[Vikash Garodia]

On 2/27/2026 10:19 PM, Konrad Dybcio wrote:
> On 2/27/26 3:11 PM, Vikash Garodia wrote:
> > Currently the driver switches the vcodec GDSC to hardware (HW) mode
> > before firmware load and boot sequence. GDSC can be powered off, keeping
> > in hw mode, thereby the vcodec registers programmed in TrustZone (TZ)
> > carry default (reset) values.
> > Move the transition to HW mode after firmware load and boot sequence.
> >
> > The bug was exposed with driver configuring different stream ids to
> > different devices via iommu-map. With registers carrying reset values,
> > VPU would not generate desired stream-id, thereby leading to SMMU fault.
> >
> > For vpu4, when GDSC is switched to HW mode, there is a need to perform
> > the reset operation. Without reset, there are occassional issues of
> > register corruption observed. Hence the vpu GDSC switch also involves
> > the reset.
>
> Is that a characteristic of the hardware (e.g. also seen downstream), or
> is that required with upstream iris only?

it was found lately with one of vpu4 variant SOC and applicable for all 
vpu4s.

> Konrad

Regards,
Vikash