On Mon 25 Oct 13:17 PDT 2021, Stephen Boyd wrote: > Quoting Bjorn Andersson (2021-10-25 12:10:35) > > On Mon 25 Oct 02:07 PDT 2021, Sandeep Maheswaram wrote: > > > > > Add multi pd bindings to set performance state for cx domain > > > to maintain minimum corner voltage for USB clocks. > > > > > > Signed-off-by: Sandeep Maheswaram <quic_c_sanm@xxxxxxxxxxx> > > > --- > > > v2: > > > Make cx domain mandatory. > > > > > > Documentation/devicetree/bindings/usb/qcom,dwc3.yaml | 8 +++++++- > > > 1 file changed, 7 insertions(+), 1 deletion(-) > > > > > > diff --git a/Documentation/devicetree/bindings/usb/qcom,dwc3.yaml b/Documentation/devicetree/bindings/usb/qcom,dwc3.yaml > > > index 2bdaba0..fd595a8 100644 > > > --- a/Documentation/devicetree/bindings/usb/qcom,dwc3.yaml > > > +++ b/Documentation/devicetree/bindings/usb/qcom,dwc3.yaml > > > @@ -42,7 +42,13 @@ properties: > > > > > > power-domains: > > > description: specifies a phandle to PM domain provider node > > > - maxItems: 1 > > > + minItems: 2 > > > + items: > > > + - description: cx power domain > > > + - description: USB gdsc power domain > > > + > > > + required-opps: > > > + description: specifies the performance state to power domain > > > > I'm still worried about the fact that we can't just rely on the USB GDSC > > being a subdomin of CX in order to just "turn on" CX. > > > > Afaict accepting this path forward means that for any device that sits > > in a GDSC power domain we will have to replicate this series for the > > related driver. > > > > I suspect the problem is that it's not just "turn on" but wanting to > turn it on and then set the performance state to some value based on the > clk frequency. I don't see an opp-table involved, just the required-opps for the purpose of turning CX on a little bit more. Perhaps I'm missing something here though. > Maybe the simplest version of that could be supported > somehow by having dev_pm_opp_set_rate() figure out that the 'level' > applies to the parent power domain instead of the child one? Having the performance_state request cascade up through the GDSC sounds like a nice solution; I've not looked at the code to see if this is feasible though. > Or we may need to make another part of the OPP binding to indicate the > relationship between the power domain and the OPP and the parent of > the power domain. I suspect this would be useful if a power-domain provider needs to translate a performance_state into a different supply-performance_state. Not sure if we have such case currently; these examples are all an adjustable power-domain with "gating" subdomains. PS. I think we have the same problem in the display subsystem, the sub-blocks are powered by MDSS_GDSC, which is a subdomain of MMCX. We trust the parent mdss node to keep the GDSC powered and specify MMCX as the power-domain for the children, so that we can affect their levels by respective opp-table. Regards, Bjorn
