Re: [PATCH v1 3/3] ARM: tegra: Add DFLL clock support on Tegra 4

[Mikko Perttunen <mperttunen@nvidia.com>]

On Monday, August 25, 2025 1:26 PM Svyatoslav wrote:
> 25 серпня 2025 р. 07:20:10 GMT+03:00, Mikko Perttunen 
<mperttunen@nvidia.com> пише:
> >On Friday, August 22, 2025 2:19 PM Svyatoslav Ryhel wrote:
> >> пт, 22 серп. 2025 р. о 06:05 Mikko Perttunen <mperttunen@nvidia.com> 
пише:
> >> > On Friday, March 21, 2025 6:55 PM Svyatoslav Ryhel wrote:
> >> > > Add DFLL clock node to common Tegra114 device tree along with clocks
> >> > > property to cpu node.
> >> > > 
> >> > > Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
> >> > > ---
> >> > > 
> >> > >  arch/arm/boot/dts/nvidia/tegra114.dtsi | 34
> >> > >  ++++++++++++++++++++++++++
> >> > >  1 file changed, 34 insertions(+)
> >> > > 
> >> > > diff --git a/arch/arm/boot/dts/nvidia/tegra114.dtsi
> >> > > b/arch/arm/boot/dts/nvidia/tegra114.dtsi index
> >> > > 341ec0962460..25d063a47ca5
> >> > > 100644
> >> > > --- a/arch/arm/boot/dts/nvidia/tegra114.dtsi
> >> > > +++ b/arch/arm/boot/dts/nvidia/tegra114.dtsi
> >> > > @@ -4,6 +4,7 @@
> >> > > 
> >> > >  #include <dt-bindings/memory/tegra114-mc.h>
> >> > >  #include <dt-bindings/pinctrl/pinctrl-tegra.h>
> >> > >  #include <dt-bindings/interrupt-controller/arm-gic.h>
> >> > > 
> >> > > +#include <dt-bindings/reset/tegra114-car.h>
> >> > > 
> >> > >  #include <dt-bindings/soc/tegra-pmc.h>
> >> > >  
> >> > >  #include "tegra114-peripherals-opp.dtsi"
> >> > > 
> >> > > @@ -710,6 +711,30 @@ mipi: mipi@700e3000 {
> >> > > 
> >> > >               #nvidia,mipi-calibrate-cells = <1>;
> >> > >       
> >> > >       };
> >> > > 
> >> > > +     dfll: clock@70110000 {
> >> > > +             compatible = "nvidia,tegra114-dfll";
> >> > > +             reg = <0x70110000 0x100>, /* DFLL control */
> >> > > +                   <0x70110000 0x100>, /* I2C output control */
> >> > > +                   <0x70110100 0x100>, /* Integrated I2C controller
> >> > > */
> >> > > +                   <0x70110200 0x100>; /* Look-up table RAM */
> >> > > +             interrupts = <GIC_SPI 62 IRQ_TYPE_LEVEL_HIGH>;
> >> > > +             clocks = <&tegra_car TEGRA114_CLK_DFLL_SOC>,
> >> > > +                      <&tegra_car TEGRA114_CLK_DFLL_REF>,
> >> > > +                      <&tegra_car TEGRA114_CLK_I2C5>;
> >> > > +             clock-names = "soc", "ref", "i2c";
> >> > > +             resets = <&tegra_car TEGRA114_RST_DFLL_DVCO>;
> >> > > +             reset-names = "dvco";
> >> > > +             #clock-cells = <0>;
> >> > > +             clock-output-names = "dfllCPU_out";
> >> > > +             nvidia,sample-rate = <11500>;
> >> > 
> >> > Should this be 12500? That would match Tegra124 and a downstream kernel
> >> > for
> >> > Tegra114 I have.
> >> 
> >> I referred to tegratab and macallan boards in 3.4 kernel which give
> >> 11500, maybe sample-rate was changed to 12500 later with tegra124
> >> addition?
> >
> >That's interesting. I was looking at the public roth (Shield Portable)
> >kernel, which does not support Tegra124. I checked the L4T r17 release
> >now, and it seems it's a newer version, where the sample rate has been
> >changed to 11500 on some boards due to a voltage undershoot issue with
> >vdd_cpu on macallan/ tegratab [1].
> >
> >So on macallan/tegratab, the vdd_cpu (smps123) ramp rate should be set to
> >2.5mV/us and sample-rate to 11500, while on other boards it can be 5mV/us
> >with 12500 for faster ramping.
> >
> >[1] https://nv-tegra.nvidia.com/r/plugins/gitiles/linux-2.6/+/
> >b92cab2d4cb6379aeded80adc4c5d0708c3f038e%5E%21/#F0
> >
> >Cheers,
> >Mikko
> 
> So should I stick with 11500 as a safer, acceptable for every t114 option?

I think it'd make sense to just put it in each board file separately. T124 DTs 
already seem to be doing that in addition to the main file.

> 
> >> > > +             nvidia,droop-ctrl = <0x00000f00>;
> >> > > +             nvidia,force-mode = <1>;
> >> > > +             nvidia,cf = <10>;
> >> > > +             nvidia,ci = <0>;
> >> > > +             nvidia,cg = <2>;
> >> > > +             status = "disabled";
> >> > > +     };
> >> > > +
> >> > > 
> >> > >       mmc@78000000 {
> >> > >       
> >> > >               compatible = "nvidia,tegra114-sdhci";
> >> > >               reg = <0x78000000 0x200>;
> >> > > 
> >> > > @@ -841,6 +866,15 @@ cpu@0 {
> >> > > 
> >> > >                       device_type = "cpu";
> >> > >                       compatible = "arm,cortex-a15";
> >> > >                       reg = <0>;
> >> > > 
> >> > > +
> >> > > +                     clocks = <&tegra_car TEGRA114_CLK_CCLK_G>,
> >> > > +                              <&tegra_car TEGRA114_CLK_CCLK_LP>,
> >> > > +                              <&tegra_car TEGRA114_CLK_PLL_X>,
> >> > > +                              <&tegra_car TEGRA114_CLK_PLL_P>,
> >> > > +                              <&dfll>;
> >> > > +                     clock-names = "cpu_g", "cpu_lp", "pll_x",
> >> > > "pll_p",
> >> > 
> >> > "dfll";
> >> > 
> >> > > +                     /* FIXME: what's the actual transition time? */
> >> > > +                     clock-latency = <300000>;
> >> > > 
> >> > >               };
> >> > >               
> >> > >               cpu@1 {