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firmware/raspberrypi: Add a get_throttled sysfs file #2397

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merged 1 commit into from Feb 27, 2018

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@notro
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commented Feb 24, 2018

This is a result of the discussion in #2367.

Kernel log:

[  530.474085] Under-voltage detected! (0x00050005)
[  534.634106] Voltage normalised (0x00000000)

A simple script that polls on the sysfs file and shows the changes:

import select
import datetime

epoll = select.epoll()

file = open("/sys/devices/platform/soc/soc:firmware/get_throttled")
epoll.register(file.fileno(), select.EPOLLPRI | select.EPOLLERR)
status = file.read()

while(True):
    epoll.poll()
    file.seek(0)
    status = file.read()
    get_throttled = int(status, 16)
    print("%s 0x%08x" % (datetime.datetime.now().strftime('%H:%M:%S'), get_throttled))

epoll.unregister(file.fileno())
file.close()

A simple proof of concept for desktop notification:

import dbus
import select
import datetime
import signal

msg = """Under-voltage is blah blah not good.
See: http://some-explanation.org
"""

def quit(signo, _frame):
    exit(0)

for sig in ('TERM', 'HUP', 'INT'):
    signal.signal(getattr(signal, 'SIG'+sig), quit);

bus = dbus.SessionBus()
notifier = bus.get_object('org.freedesktop.Notifications', '/org/freedesktop/Notifications')
iface = dbus.Interface(notifier, 'org.freedesktop.Notifications')
nid = None

epoll = select.epoll()
file = open("/sys/devices/platform/soc/soc:firmware/get_throttled")
epoll.register(file.fileno(), select.EPOLLPRI | select.EPOLLERR)
status = file.read()

while(True):
    epoll.poll()
    file.seek(0)
    status = file.read()
    get_throttled = int(status, 16)

    if get_throttled & (1 << 16):
        try:
            nid = iface.Notify('get_throttled', 0, 'dialog-warning', 'Under-voltage!', msg, [], {}, 0)
        except dbus.exceptions.DBusException as e:
            sys.stderr.write("Error sending notification: %s\n" % e); sys.stderr.flush()
    elif nid:
        try: # The user might have closed it
            iface.CloseNotification(nid)
        except dbus.exceptions.DBusException:
            pass
        nid = None

epoll.unregister(file.fileno())
file.close()

dbus notification daemon (supports cancelling notifications):

sudo apt install dunst
firmware/raspberrypi: Add a get_throttled sysfs file
Under-voltage due to inadequate power supplies is a recurring problem for
new Raspberry Pi users. There are visual indications that an
under-voltage situation is occuring like blinking power led and a
lightning icon on the desktop (not shown when using the vc4 driver), but
for new users it's not obvious that this signifies a critical situation.

This patch provides a twofold improvement to the situation:

Firstly it logs under-voltage events to the kernel log. This provides
information also for headless installations.

Secondly it provides a sysfs file to read the value. This improves on
'vcgencmd' by providing change notification. Userspace can poll on the
file and be notified of changes to the value.
A script can poll the file and use dbus notification to put a windows on
the desktop with information about the severity with a recommendation to
change the power supply. A link to more information can also be provided.
Only changes to the sticky bits are reported (cleared between readings).

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
pr_info("Voltage normalised (0x%08x)\n", *value);
}

sysfs_notify(&fw->cl.dev->kobj, NULL, "get_throttled");

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@pelwell

pelwell Feb 27, 2018

Contributor

I know the polling rate is very low so the answer is largely moot, but is there a reason for waking any waiters regardless of whether the state has changed?

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@notro

notro Feb 27, 2018

Author Contributor

We only reach this if there are changes, see a couple of lines up:

if (new_sticky == old_sticky)
	return 0;
@pelwell

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commented Feb 27, 2018

No objections.

@popcornmix popcornmix merged commit daa138d into raspberrypi:rpi-4.14.y Feb 27, 2018

popcornmix added a commit to raspberrypi/firmware that referenced this pull request Mar 5, 2018
kernel: Bump to 4.14.24
kernel: Fix GCC 6.4.0 and 7.3.0 warnings
See: raspberrypi/linux#2413

kernel: audioinjector-octo: Add continuous clock feature
See: raspberrypi/linux#2409

kernel: overlays: Add 'upstream' overlay
See: raspberrypi/linux#2393

kernel: overlays: Add overlay for PiBell soundcard
See: https://www.raspberrypi.org/forums/viewtopic.php?f=44&t=99784&p=1279490#p1278971

kernel: Removing (broken) RaspiDac3 support

kernel: i2c: bcm2835: Set up the rising/falling edge delays
See: raspberrypi/linux#2407

kernel: overlays: Add updated mmc1 alias to sdio overlays

kernel: config: Enable CONFIG_GPIO_MOCKUP module
See: raspberrypi/linux#2410

kernel: overlays: Rework sdio overlays to allow polling
See: raspberrypi/linux#2401

kernel: firmware/raspberrypi: Add a get_throttled sysfs file
See: raspberrypi/linux#2397

firmware: dtoverlay: Also allow fragment-<n> in overlays

firmware: i2c_gpio: Optimise and run clients faster
popcornmix added a commit to Hexxeh/rpi-firmware that referenced this pull request Mar 5, 2018
kernel: Bump to 4.14.24
kernel: Fix GCC 6.4.0 and 7.3.0 warnings
See: raspberrypi/linux#2413

kernel: audioinjector-octo: Add continuous clock feature
See: raspberrypi/linux#2409

kernel: overlays: Add 'upstream' overlay
See: raspberrypi/linux#2393

kernel: overlays: Add overlay for PiBell soundcard
See: https://www.raspberrypi.org/forums/viewtopic.php?f=44&t=99784&p=1279490#p1278971

kernel: Removing (broken) RaspiDac3 support

kernel: i2c: bcm2835: Set up the rising/falling edge delays
See: raspberrypi/linux#2407

kernel: overlays: Add updated mmc1 alias to sdio overlays

kernel: config: Enable CONFIG_GPIO_MOCKUP module
See: raspberrypi/linux#2410

kernel: overlays: Rework sdio overlays to allow polling
See: raspberrypi/linux#2401

kernel: firmware/raspberrypi: Add a get_throttled sysfs file
See: raspberrypi/linux#2397

firmware: dtoverlay: Also allow fragment-<n> in overlays

firmware: i2c_gpio: Optimise and run clients faster
@Cyr-ius

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commented Mar 17, 2018

I compiled the last kernel 4.14.27 and since then I have the following message in loop in the kern.log
raspberrypi-firmware soc:firmware: Request 0x00030046 returned status 0x80000001
and i have no problem of under voltage
Pi Zero W
vcgencmd measure_clock arm
frequency(45)=1000106000
vcgencmd measure_clock core
frequency(1)=400000000
vcgencmd measure_volts
volt=1.2000V

vcgencmd measure_temp; vcgencmd get_throttled; vcgencmd measure_temp
temp=37.9'C
throttled=0x0
temp=37.9'C

I have the problem on my Pi Zero and Pi 2

How to stop this message ?

@pelwell

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commented Mar 17, 2018

Answered elsewhere.

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