Hi, Viresh > On 04-07-19, 07:49, Leonard Crestez wrote: > > On 7/4/2019 9:23 AM, anson.hu...@nxp.com wrote: > > > From: Anson Huang <anson.hu...@nxp.com> > > > > > > Assign highest OPP as suspend OPP to reduce suspend/resume latency > > > on i.MX8MM. > > > > > > Signed-off-by: Anson Huang <anson.hu...@nxp.com> > > > --- > > > arch/arm64/boot/dts/freescale/imx8mm.dtsi | 1 + > > > 1 file changed, 1 insertion(+) > > > > > > diff --git a/arch/arm64/boot/dts/freescale/imx8mm.dtsi > > > b/arch/arm64/boot/dts/freescale/imx8mm.dtsi > > > index b11fc5e..3a62407 100644 > > > --- a/arch/arm64/boot/dts/freescale/imx8mm.dtsi > > > +++ b/arch/arm64/boot/dts/freescale/imx8mm.dtsi > > > @@ -136,6 +136,7 @@ > > > opp-microvolt = <1000000>; > > > opp-supported-hw = <0x8>, <0x3>; > > > clock-latency-ns = <150000>; > > > + opp-suspend; > > > }; > > > }; > > > > What if the highest OPP is unavailable due to speed grading? > > What does this exactly mean ? How is the OPP made unavailable in your > case ?
That is because in i.MX8M series SoCs, the speed grading and market segment fuses settings could affect the OPP defined in DT, in a word, all possible OPPs are defined in DT, but each parts could ONLY select some of them to be working OPPs, so if the "opp-suspend" is added for 1 OPP in DT, if the part's speed grading or market segment fuse settings make that OPP as unavailable, then that "opp-suspend" is NOT working at all. > > What will dev_pm_opp_get_suspend_opp_freq() return in this case ? If the OPP contains "opp-suspend" property is NOT supported by the HW, then there will be no suspend OPP defined, so it will return 0. The _opp_is_supported() parses the opp-supported-hw before opp-suspend. > > > Ideally we > > should find a way to suspend at the highest *supported* OPP. > > > > Maybe the opp-suspend marking could be assigned from imx-cpufreq-dt > > driver code? I ever tried that, go through the OPP table and check the fuse settings, then runtime add "opp-suspend" to the opp table, but unfortunately, the " struct opp_table " is NOT opened to be used, it is a private structure? > > Sorry for jumping in late, the latest patch from Anson drew my attention to > this topic :) That is OK😊 Thanks, Anson.
