force_turbo sets incorrect vcore

[Fourdee]

As per: https://www.raspberrypi.org/forums/viewtopic.php?p=1045575#p1045575

Setting force_turbo=1 results in a lower/incorrect vcore, when measured with vcgencmd measure_volts

Confirmed with RPi Zero (possibly related to all RPi's: https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=160939&hilit=vcgencmd)

Test with RPi Zero:

• Zero 1.3
• 4.4.21+
• Performance CPU gov.
• Get core voltage with: vcgencmd measure_volts
• Default core voltage @ 1ghz =1.3500V

force_turbo=1
volt=1.2000V

[popcornmix]

I set force_turbo=1 in config.txt and I see:

pi@raspberrypi:~ $ vcgencmd measure_volts
volt=1.3500V

Report output of

vcgencmd version
vcgencmd get_config int
vcgencmd measure_clock arm
vcgencmd measure_clock core
vcgencmd measure_volts

[Fourdee]

@popcornmix

RPi Zero.

config.txt, enabled entries only:

disable_overscan=1
framebuffer_width=1280
framebuffer_height=720
start_x=0
disable_camera_led=0
gpu_mem_256=16
gpu_mem_512=16
gpu_mem_1024=16
max_usb_current=1
disable_pvt=1
disable_splash=1
avoid_pwm_pll=1
dtparam=audio=off
dtparam=i2c_arm=off
dtparam=i2c1=off
i2c_arm_baudrate=100000
dtparam=spi=off
temp_limit=65
initial_turbo=20
force_turbo=1

root@DietPi:~# vcgencmd version
Sep 21 2016 13:14:13
Copyright (c) 2012 Broadcom
version 2eaf52cc53435b5ce67253af1487f9a4f9f96e2d (clean) (release)
root@DietPi:~# vcgencmd get_config int
arm_freq=1000
audio_pwm_mode=1
config_hdmi_boost=5
core_freq=400
disable_auto_turbo=1
disable_commandline_tags=2
disable_splash=1
enable_uart=1
force_eeprom_read=1
force_pwm_open=1
force_turbo=1
framebuffer_depth=16
framebuffer_height=720
framebuffer_ignore_alpha=1
framebuffer_swap=1
framebuffer_width=1280
gpu_freq=300
hdmi_force_cec_address=65535
ignore_lcd=1
init_uart_clock=0x2dc6c00
initial_turbo=20
mask_gpu_interrupt1=0x10000
max_usb_current=1
over_voltage_avs=0x249f0
pause_burst_frames=1
program_serial_random=1
sdram_freq=450
temp_limit=65
root@DietPi:~# vcgencmd measure_clock arm
frequency(45)=700000000
root@DietPi:~# vcgencmd measure_clock core
frequency(1)=250000000
root@DietPi:~# vcgencmd measure_volts
volt=1.2000V

CPUfreq reports 1ghz:

root@DietPi:~# cat /sys/devices/system/cpu/cpufreq/policy0/scaling_cur_freq
1000000
root@DietPi:~# cat /sys/devices/system/cpu/cpufreq/policy0/scaling_governor
performance

[popcornmix]

What about:

vcgencmd measure_temp
vcgencmd get_throttled

[Fourdee]

@popcornmix

root@DietPi:~# vcgencmd measure_temp
temp=34.7'C
root@DietPi:~# vcgencmd get_throttled
throttled=0x0

[popcornmix]

Try removing initial_turbo=20

[Fourdee]

@popcornmix

Try removing initial_turbo=20

Yep, that did it 👍

root@DietPi:~# vcgencmd measure_clock arm
frequency(45)=1000104000

[popcornmix]

Okay, that is a bug.
force_turbo and initial_turbo don't make sense together, and the end of the initial_turbo time is disabling turbo mode. Should be easy to fix.

[popcornmix]

Test firmware you can try: https://www.dropbox.com/s/oo5f4ztfozgeg06/firmware_ip.zip?dl=0

[Ruffio]

@Fourdee has this issue been resolved with the above firmware?

[Fourdee]

@Ruffio
Unsure, will test and confirm results tomorrow.

[Fourdee]

@Ruffio
Yep, resolved with latest firmware/kernel 4.4.38+ from Raspbian repo 👍 :

root@DietPi:~# vcgencmd measure_volts
volt=1.3500V
root@DietPi:~# cat /DietPi/config.txt | grep force_turbo
force_turbo=1
root@DietPi:~# uname -a
Linux DietPi 4.4.38+ #938 Thu Dec 15 15:17:54 GMT 2016 armv6l GNU/Linux

Thanks @popcornmix. @Ruffio this is now resolved and can be closed.