Re: [PATCH DNM RFC 13/16] arm64: dts: qcom: sm8650: Describe clock controller power rails

[Dmitry Baryshkov]

On Wed, Oct 14, 2026 at 04:20:08PM +0200, Konrad Dybcio wrote:
> On 10/14/26 4:19 PM, Dmitry Baryshkov wrote:
> > On Wed, Oct 14, 2026 at 02:19:13PM +0200, Konrad Dybcio wrote:
> >> From: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx>
> >>
> >> The SM8650 clock-controller nodes omit rails needed by their clocks and
> >> PLLs. Without those connections, the clock-owned DVFS implementation
> >> cannot attach its voters to all required domains and controller probe
> >> can fail before any clocks are registered.
> >>
> >> Fixes: d2350377997f ("arm64: dts: qcom: add initial SM8650 dtsi")
> >> Assisted-by: LLM
> >> Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx>
> >> ---
> >>  arch/arm64/boot/dts/qcom/sm8650.dtsi | 16 +++++++++++-----
> >>  1 file changed, 11 insertions(+), 5 deletions(-)
> >>
> >> @@ -6049,8 +6055,8 @@ dispcc: clock-controller@af00000 {
> >>  				 <0>, /* dp3 */
> >>  				 <0>;
> >>  
> >> -			power-domains = <&rpmhpd RPMHPD_MMCX>;
> >> -			required-opps = <&rpmhpd_opp_low_svs>;
> > 
> > I think this is neccessary (at least on some platforms) to keep MMCX out
> > of retention. Even if we can drop it here, I don't think we can drop it
> > for older platforms.
> 
> MMCX exists precisely to let you turn it off, the clock patches
> retain a way to keep the clock on during the runtime-resume of
> the clock controller driver

Turning off MMCX is possible together with suspending the dispcc. If
dispcc is resumed, MMCX should be at least low_svs. On some platforms
it's handled by the cmd-db, where MMCX has a minimal value of low_svs.
On other platforms MMCX lists 'RET' as a possible value, however it's
not enough for dispcc (or other CCs) to work. In theory, *I think*, it's
exactly what 'GCC_DISP_AHB_CLK' might need to vote, but we don't
represent it.

-- 
With best wishes
Dmitry