flipping frames bug and workaround

[zetabeta]

i forgot this link:

https://gitlab.com/postmarketOS/pmaports/-/issues/805

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how to reproduce powersaving bug:

this is more difficult to replicate. what i know all pinephones are affected.

default settings are applied for gpu pwersaving. some kind of visible script is run on screen, which uses gpu somewhat, but in a way that gpu goes to powersaving for awhile. on a background, maybe ssh, one runs something which consumes networking and cpu power. mobile data and ethernet is more likely to reproduce this bug, but wifi is less likely. this may take hours.

Code:

# udev rule. this prevents frequency part only
# example file location /lib/udev/rules.d/98-test.rules
# reboot required
# powersaving part
#KERNEL=="1c40000.gpu", SUBSYSTEM=="platform", DRIVER=="lima", ATTR{power/autosuspend_delay_ms}="-1"
#KERNEL=="1c40000.gpu", SUBSYSTEM=="platform", DRIVER=="lima", ATTR{power/control}="on"
# frequency part, may not be needed
KERNEL=="1c40000.gpu", SUBSYSTEM=="devfreq", ATTR{min_freq}="432000000"
KERNEL=="1c40000.gpu", SUBSYSTEM=="devfreq", ATTR{max_freq}="432000000"

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how to reproduce frequency bug:

only some pinephones are affected. fedora (dirty) kernel is/was not affected for frequency part).

isome settings for gpu needs to be initiated, because powersaving should be ruled out. something needs to be done a screen, maybe glxgears. on a background like ssh, frequency change script is run. crash probably happens in minutes.

Code:

# udev rule. this prevents powersaving part only
# example file location /lib/udev/rules.d/98-test.rules
# reboot required
# powersaving part
KERNEL=="1c40000.gpu", SUBSYSTEM=="platform", DRIVER=="lima", ATTR{power/autosuspend_delay_ms}="-1"
KERNEL=="1c40000.gpu", SUBSYSTEM=="platform", DRIVER=="lima", ATTR{power/control}="on"
# frequency part, may not be needed
#KERNEL=="1c40000.gpu", SUBSYSTEM=="devfreq", ATTR{min_freq}="432000000"
#KERNEL=="1c40000.gpu", SUBSYSTEM=="devfreq", ATTR{max_freq}="432000000"

Code:

# stupid bash script to forcibly change frequency at all time
# root or sudo required
# options are 432000000 312000000 120000000.
# you may need 432<>312 or 432<>120 or 312<>120

echo 432000000 > /sys/class/devfreq/1c40000.gpu/min_freq
echo 432000000 > /sys/class/devfreq/1c40000.gpu/max_freq

while true
do echo 432000000 > /sys/class/devfreq/1c40000.gpu/max_freq
echo 312000000 > /sys/class/devfreq/1c40000.gpu/max_freq
done

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frequency bug happens only in some pinephones, so i ask, can you test frequency part in your pinephone, and also report hardware version.

https://wiki.pine64.org/wiki/PinePhone#H..._revisions

i put this thread for wider discussion about mali gpu and a driver for it. does mali chip have some deficiencies? has anyone some knowledge what's going on in lima driver? why some devices are affected and others aren't? is frequency change reliable?

even related information could be helpful.