On Mon, Sep 9, 2019 at 1:11 PM H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> wrote: > > > > Am 09.09.2019 um 18:54 schrieb H. Nikolaus Schaller <hns@xxxxxxxxxxxxx>: > > > > Hi Tony, > > > >> Am 09.09.2019 um 18:32 schrieb Tony Lindgren <tony@xxxxxxxxxxx>: > >> > >> Hi, > >> > >> * H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> [190909 14:57]: > >>> Another question that came up by private mail from André was if we > >>> should better disable the turbo OPPs of omap34xx and 36xx by default > >>> (status = "disabled";) because there are concerns about overheating > >>> the chips and we have no thermal regulation like for omap4 & 5. > >>> > >>> But this would mean that every board DTS would have to set it explicitly > >>> to "enabled". > >> > >> Yes I started thinking about that too. I think there is a requirement > >> to do the scaling via the voltage processor for the higher modes. > > > > It depends on how you read the little footnotes... > > > > Table 4-18. Processor Voltages Without SmartReflex: > > > > • This table defines the safe VDD1 (vdd_mpu_iva) voltage ranges to be used before using the SmartReflex AVS feature for OPPs calibration. > > • Values are defined when SmartReflexTM feature is deactivated. They can be lower when SmartReflexTM is activated. > > • OPP130 and OPP1G are not available above TJ of 90C. > > • (6) OPP1G is a high performance operating point which has following requirements: > > • – ABB LDO must be set to FBB (Forward Body Bias) mode when switching to this OPP. It requires having a 1 F capacitor connected to cap_vdd_bb_mpu_iva. > > • – AVS (Adaptive Voltage Scaling) power technique must be used to achieve optimum operating voltage. > > > > So I read this as: > > > > * OPP130 and OPP1G should be guarded by 90°C thermal framework > > * OPP1G should also set the ABB LDO to FBB mode > > * AVS does only reduce voltage levels (to save energy = heat = problem) > > * only if we want "optimum operating voltage" (read as: "lowest possible voltage" = "highest energy saving") we must use AVS > > > > I.e. we do not necessarily need AVS or SmartReflex or help from the > > twl4030 (except for changing the voltage). > > > >> And there needs to be some way to automatically change to a lower > >> OPP in some cases. > > > > That should probably be done through the thermal framework like > > on omap4 & omap5? > > > >> > >> For normal OPPs, using the twl regulator directly should be OK. > > > > Maybe for the turbo OPPs as well. > > > >> For the higher modes, maybe we could pass the callback functions > >> from arch/arm/mach-omap2/voltage.c for the twl regulator so the > >> voltage processor hardware can handle them directly. Or add a > >> separate regulator driver operating the voltages like Nishanth > >> posted patches for earlier. > > > > So in my (limited) understanding it would suffice to set the ABB LDO > > to FBB mode for OPP1G. > > Ok, we have to check if the ti,abb-v2 "LDO" driver > drivers/regulator/ti-abb-regulator.c > can handle that with a DT entry similar to: > > https://elixir.bootlin.com/linux/latest/source/arch/arm/boot/dts/omap5.dtsi#L365 At least for the 3630, the ti-abb-regulator driver is the same driver, but different structures based on v1, v2, or v3 are used based on which compatible flag is used. I tried enabling the vbb-supply in the device tree, but the driver doesn't load it without .multi_regulator being true. cpus { /* OMAP3630/OMAP37xx variants OPP50 to OPP130 and OPP1G */ cpu: cpu@0 { operating-points-v2 = <&cpu0_opp_table>; vbb-supply = <&abb_mpu_iva>; clock-latency = <300000>; /* From omap-cpufreq driver */ }; }; I enabled that in the 3630 structure, but then the opp must list voltage points for both regulators. Looking at the entry for abb_mpu_iva, it appears to have voltages that directly match the OPP table, so I made a duplicate entry: opp-microvolt = <1012500 1012500 1012500>, <1012500 1012500 1012500>; and similar for 600, 800 and 1000 similar to the way dra7.dtsi does it, but then I got some nasty errors and crashes. I started undoing the stuff, and I wanted to see if the abb_mpu_iva regulator was even running, but I would get -22 errors when I went to read the voltage. # cat /sys/devices/platform/68000000.ocp/483072f0.regulator-abb-mpu/regulator/regulator.5/microvolts -22 If someone has any suggestions on how to test the abb_mpu_iva driver, let me know. > > Needs a little time to add to a new version of the patch set. > > > And make sure that the TJ does not exceed 90°C by reducing the cpufreq > > through the thermal framework. But: the thermal sensors of the omap3 > > are quite odd (they seem to jump up by 10° after first use). Can we just do a dummy read to get it out of the way? ;-) > > I'll leave this out for the moment for future study. Works for me, Baby steps. Thanks for all your work. adam > > BR and thanks, > Nikolaus >
