how i can make enable the DVFS of L4T R28.2 ?

Autonomous Machines Jetson & Embedded Systems Jetson TX2
#1

hello nv team,

i found there are a few of tegra210 DVFS menus in the tegra18_defconfig of L4T R28.2. but i could not find any DVFS menu for tegra18 especially for tx2.

│ Symbol: TEGRA_DVFS [=n]                                                                                                                                    │  
  │ Type  : boolean                                                                                                                                            │  
  │   Defined at drivers/soc/tegra/Kconfig:35                                                                                                                  │  
  │   Depends on: ARCH_TEGRA [=y]                                                                                                                              │  
  │   Selects: PM_OPP [=n]                                                                                                                                     │  
  │   Selected by: TEGRA_210_DVFS [=n] && ARCH_TEGRA_210_SOC [=n]                                                                                              │  
  │
#2

Hi,

DVFS is moved to a ARM R5 processor, we call it BPMP and it takes care of cpu dvfs. We dont want customer to play with the dvfs settings as its Chip SKU specific. But if you have any specific requirement, let us know.
Like want to peg the max freq or dont want some freq.

regards
Bibek

#3

thanks bbasu

i found there are a few of definition about the BPMPs
tegra186-soc-base.dtsi

...
1320     bpmp {
1321         compatible = "nvidia,tegra186-bpmp";
1322         #stream-id-cells = <1>;
1323         reg = <0x0 0x0d000000 0x0 0x00800000>,
1324               <0x0 0x3004e000 0x0 0x00001000>,
1325               <0x0 0x3004f000 0x0 0x00001000>;
1326         status = "disabled";
1327 
1328         bpmpthermal: bpmpthermal {
1329             compatible = "nvidia,tegra186-bpmp-thermal";
1330             #thermal-sensor-cells = <1>;
1331             status = "disabled";
1332         };
1333     };
...

and its linux driver is bpmp.c

...
385 static const struct of_device_id bpmp_of_matches[] = {
386     { .compatible = "nvidia,tegra186-bpmp", .data = &t186_native_cfg },
387     { .compatible = "nvidia,tegra186-bpmp-hv", .data = &t186_hv_cfg },
388     { .compatible = "nvidia,tegra210-bpmp", .data = &t210_cfg },
389     {}
390 };
...

so i want to know how to set up if i want to make max freq for best performance ?
previously thanks ~

#4

Just set the cpufreq governor to performance in Linux kernel

#5

hi bbasu

thanks your reply,

i have two more questions,

first, as you mention above, the tx2 DVFS can be activated, with only two conditions are met, is it right ?

second, how could i verify whether the dvfs functionality is doing something with simple maner, for example, /sys or etc ??

#6

Hi,

Yeah, Max-min setting and removal of any freq from the list.
you can run tegrastats from /home/nvidia and see the freq changing based on dvfs when your usecase is running

./tegrastats

thanks
Bibek