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* arm:xlnx,zynq-7000: missing CPU freq in /sys after 6.18.0-g8f7aa3d3c732 from 2025-12-04
@ 2025-12-08 16:58 Pavel Pisa
  2025-12-09  5:37 ` Viresh Kumar
  0 siblings, 1 reply; 8+ messages in thread
From: Pavel Pisa @ 2025-12-08 16:58 UTC (permalink / raw)
  To: Michal Simek, Rafael J. Wysocki, Viresh Kumar, linux-pm; +Cc: Pavel Hronek

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Dear maintainers and developers,

we are running CAN/CAN FD subsystem daily correct function
and latency evaluation on Zynq platform with our CAN FD IPs
on mainline and RT kernels for years already

  https://canbus.pages.fel.cvut.cz/#can-bus-channels-mutual-latency-testing

and we experience problem that attempt to set performance
scaling governor though

  /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
  /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor

started to fail on mainline kernels. The last day
when setting worked has been 2025-12-04 with
6.18.0-g8f7aa3d3c732 kernel. Then the cpufreq
/sys interface seems to be missing.

I have checked boot even with latest DTB and the
intreface is missing still. The driver seems to be
present

  /sys/bus/platform/drivers/cpufreq-dt

the code builds cpufreq-dt-platdev.o which contains
"xlnx,zynq-7000". The directory

  /sys/devices/system/cpu/cpufreq

is present, but it is empty. The module is present and
linked into kernel

  /sys/module/cpufreq

The next config options are set

  CONFIG_CPUFREQ_DT=y
  CONFIG_CPUFREQ_DT_PLATDEV=y

The whole kernel configuration is attached.

Please, have you some idea what could be a problem?
Is it necessary to update something or is something missing
in the device tree?

I can try to bisect to exact commit or add some debugging
printks into kernel to obtain more information,
but it would take some time. What else do you suggest?

Best wishes,

                Pavel

                Pavel Pisa
    phone:      +420 603531357
    e-mail:     pisa@cmp.felk.cvut.cz
    Department of Control Engineering FEE CVUT
    Karlovo namesti 13, 121 35, Prague 2
    university: http://control.fel.cvut.cz/
    personal:   http://cmp.felk.cvut.cz/~pisa
    social:     https://social.kernel.org/ppisa
    projects:   https://www.openhub.net/accounts/ppisa
    CAN related:http://canbus.pages.fel.cvut.cz/
    RISC-V education: https://comparch.edu.cvut.cz/
    Open Technologies Research Education and Exchange Services
    https://gitlab.fel.cvut.cz/otrees/org/-/wikis/home

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^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2025-12-10  4:58 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-12-08 16:58 arm:xlnx,zynq-7000: missing CPU freq in /sys after 6.18.0-g8f7aa3d3c732 from 2025-12-04 Pavel Pisa
2025-12-09  5:37 ` Viresh Kumar
2025-12-09  5:39   ` Viresh Kumar
2025-12-09 13:47   ` Pavel Pisa
2025-12-10  4:12     ` Viresh Kumar
2025-12-10  4:40       ` Krzysztof Kozlowski
2025-12-10  4:48         ` Viresh Kumar
2025-12-10  4:58           ` Krzysztof Kozlowski

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