Re: [PATCH 2/2] arm64: dts: qcom: sm8550: Additionally manage MXC power domain in camcc

Dmitry Baryshkov
2025-03-13T07:26:15Z

On Thu, Mar 13, 2025 at 10:09:05AM +0530, Taniya Das wrote:
>
>
> On 3/4/2025 2:10 PM, Dmitry Baryshkov wrote:
> > On Tue, 4 Mar 2025 at 09:37, Vladimir Zapolskiy
> > <vladimir.zapolskiy@linaro.org> wrote:
> >>
> >> On 3/4/25 01:53, Dmitry Baryshkov wrote:
> >>> On Tue, Mar 04, 2025 at 12:55:21AM +0200, Vladimir Zapolskiy wrote:
> >>>> SM8550 Camera Clock Controller shall enable both MXC and MMCX power
> >>>> domains.
> >>>
> >>> Are those really required to access the registers of the cammcc? Or is
> >>> one of those (MXC?) required to setup PLLs? Also, is this applicable
> >>> only to sm8550 or to other similar clock controllers?
> >>
> >> Due to the described problem I experience a fatal CPU stall on SM8550-QRD,
> >> not on any SM8450 or SM8650 powered board for instance, however it does
> >> not exclude an option that the problem has to be fixed for other clock
> >> controllers, but it's Qualcomm to confirm any other touched platforms,
> >
> > Please work with Taniya to identify used power domains.
> >
>
> CAMCC requires both MMCX and MXC to be functional.
>
> >> for instance x1e80100-camcc has it resolved right at the beginning.
> >>
> >> To my understanding here 'required-opps' shall also be generalized, so
> >> the done copy from x1e80100-camcc was improper, and the latter dt-binding
> >> should be fixed.
> >
> > Yes
> >
>
> required-opps is not mandatory for MXC as we ensure that MxC would never
> hit retention.
>
> https://lore.kernel.org/r/20240625-avoid_mxc_retention-v2-1-af9c2f549a5f@quicinc.com

Yes. And the code in genpd_set_required_opp() tolerates not seting the
extra opps. However I'd certainly suggest not doing that (I think
passing <0> should work). Having different number of items in
power-domains and required-opps makes it harder to read the DT.

--
With best wishes
Dmitry