Hi Sergio. First of all, thank you (and anyone else involved) for your time investigating in the issue.
> Could you please try to run the command several times, specifying the different chip I did not find how to specify a certain chip with the 'sensors' command after reading the man page. But I'm sure the problem happens when sensors tries to read the temperature from the AMD discrete graphics card, because when the console output of sensors reaches this section during the scan: amdgpu-pci-0100 Adapter: PCI adapter [ --> HERE IT HANGS FOR 2 SECS <-- ] vddgfx: 1.05 V edge: +42.0°C (crit = +94.0°C, hyst = -273.1°C) power1: 7.11 W (cap = 35.00 W) it hangs for a couple of seconds and two things happens: 1. the fans start spinning 2. I see an drm related warning appearing in the dmesg logs: [ 41.397707] [drm] PCIE GART of 256M enabled (table at 0x000000F400000000). [ 42.609649] [drm:dce110_edp_wait_for_hpd_ready [amdgpu]] *ERROR* dce110_edp_wait_for_hpd_ready: wait timed out! [ 43.213733] [drm:dce110_edp_wait_for_hpd_ready [amdgpu]] *ERROR* dce110_edp_wait_for_hpd_ready: wait timed out! [ 43.242390] [drm] UVD and UVD ENC initialized successfully. [ 43.352370] [drm] VCE initialized successfully. [ 43.358578] amdgpu 0000:01:00.0: [drm] Cannot find any crtc or sizes Could it be that scanning the amdgpu-pci-0100 causes the AMD card to reset and this is related to the fans starting ? > you were able to reproduce this problem not only in Ubuntu, but also in other distributions. Is that correct ? I was able to reproduce on Ubuntu 20.04 with all 5.8 kernels available and with a 5.10.0-14 kernel installed from Hirsute beta repositories. However today I made some tests again using my stable 20.04 and also the just released final Hirsute 21.04 from a live USB. Below the results of running the 'sensors' command in terminal, ordered by Ubuntu version and kernel: 1. 20.04, 5.4.0-59-generic #65-Ubuntu SMP - everything ok - no fans spinning - no dmesg warinings - no sensors hanging during scan: amdgpu-pci-0100 Adapter: PCI adapter vddgfx: N/A edge: N/A (crit = +94.0°C, hyst = -273.1°C) power1: N/A (cap = 35.00 W) 2. 20.04, 5.8.0-50-generic #56~20.04.1-Ubuntu SMP - problem present - fans spinning - sensors hangs during output when reaching amd section: amdgpu-pci-0100 Adapter: PCI adapter [ 2 SECS ] vddgfx: 1.05 V edge: +38.0°C (crit = +94.0°C, hyst = -273.1°C) power1: 7.12 W (cap = 35.00 W) - dmesg warnings appearing when fans start: [ 41.397707] [drm] PCIE GART of 256M enabled (table at 0x000000F400000000). [ 42.609649] [drm:dce110_edp_wait_for_hpd_ready [amdgpu]] *ERROR* dce110_edp_wait_for_hpd_ready: wait timed out! [ 43.213733] [drm:dce110_edp_wait_for_hpd_ready [amdgpu]] *ERROR* dce110_edp_wait_for_hpd_ready: wait timed out! [ 43.242390] [drm] UVD and UVD ENC initialized successfully. [ 43.352370] [drm] VCE initialized successfully. [ 43.358578] amdgpu 0000:01:00.0: [drm] Cannot find any crtc or sizes 3. USB/Live 21.04, 5.11.0-16-generic #17-Ubuntu SMP - problem present - fans spinning - sensors hangs during output when reaching amd section: amdgpu-pci-0100 Adapter: PCI adapter [ 2 SECS ] vddgfx: 1.05 V edge: +38.0°C (crit = +94.0°C, hyst = -273.1°C) power1: 7.12 W (cap = 35.00 W) - dmesg warnings appearing when fans start (slightly different from 5.8.0-50): [ 301.476682] [drm] PCIE GART of 256M enabled (table at 0x000000F400000000). [ 301.681312] [drm] UVD and UVD ENC initialized successfully. [ 301.791290] [drm] VCE initialized successfully. [ 301.797151] amdgpu 0000:01:00.0: [drm] Cannot find any crtc or sizes [ 302.099911] drm_dp_i2c_do_msg: 14 callbacks suppressed [ 302.196470] [drm:lspcon_init [i915]] *ERROR* Failed to probe lspcon [ 302.196534] [drm:lspcon_resume [i915]] *ERROR* LSPCON init failed on port D [ 303.115752] [drm:lspcon_init [i915]] *ERROR* Failed to probe lspcon [ 303.115829] [drm:lspcon_resume [i915]] *ERROR* LSPCON init failed on port D So the only kernel without this problem is the old 5.4, but I suspect that with that kernel the sensor real measurement is not happening because there are no voltage/temps readings but only N/A (maybe it was not yet implemented and this is only a stub/dummy output) > If it is, do you think you could test a pristine Linux kernel (from > https://kernel.org)? I'll try as soon as possible and report back the results. In the meantime, thanks again and please feel free to ask any more questions/tests. Regards, Gabriele. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1910562 Title: Fans switching on and off every 10 seconds after update to kernel 5.8.0-34 Status in linux package in Ubuntu: Incomplete Status in linux-signed-hwe-5.8 package in Ubuntu: Confirmed Status in lm-sensors package in Ubuntu: New Status in xserver-xorg-video-amdgpu package in Ubuntu: Invalid Bug description: After updating via apt dist-upgrade from kernel 5.4.0-59 to kernel 5.8.0-34 the fan on my machine started switching on (for an instant) and off every 10 seconds even when idle with CPU at 48/50°C. Switching back to previous kernel solves temporary the problem, i.e. fans are always off with light desktop work. The new behavior is really annoying and I guess not healthy for the fans. I'm on latest Dell bios, with every other package updated. Di something in the thermal policies change between those two kernels? Is it possible to go back to previous behavior ? Thanks in advance for help Machine: Dell Precison 7540, intel i7-9750 ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: linux-image-5.8.0-34-generic 5.8.0-34.37~20.04.2 ProcVersionSignature: Ubuntu 5.8.0-34.37~20.04.2-generic 5.8.18 Uname: Linux 5.8.0-34-generic x86_64 ApportVersion: 2.20.11-0ubuntu27.14 Architecture: amd64 CasperMD5CheckResult: skip CurrentDesktop: ubuntu:GNOME Date: Thu Jan 7 17:14:54 2021 InstallationDate: Installed on 2020-05-06 (246 days ago) InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423) SourcePackage: linux-signed-hwe-5.8 UpgradeStatus: No upgrade log present (probably fresh install) --- ProblemType: Bug ApportVersion: 2.20.11-0ubuntu27.16 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: gabriele 2370 F.... pulseaudio /dev/snd/controlC1: gabriele 2370 F.... pulseaudio CasperMD5CheckResult: skip CurrentDesktop: ubuntu:GNOME DistroRelease: Ubuntu 20.04 InstallationDate: Installed on 2020-05-06 (352 days ago) InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423) MachineType: Dell Inc. Precision 7540 Package: lm-sensors 1:3.6.0-2ubuntu1 PackageArchitecture: amd64 ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.8.0-50-generic root=UUID=c39f518b-f5c9-47c5-8e7f-42d970d2dedb ro quiet splash vt.handoff=7 ProcVersionSignature: Ubuntu 5.8.0-50.56~20.04.1-generic 5.8.18 RelatedPackageVersions: linux-restricted-modules-5.8.0-50-generic N/A linux-backports-modules-5.8.0-50-generic N/A linux-firmware 1.187.11 Tags: focal Uname: Linux 5.8.0-50-generic x86_64 UpgradeStatus: No upgrade log present (probably fresh install) UserGroups: adm audio cdrom dialout dip docker lpadmin lxd plugdev sambashare sudo vboxusers wireshark _MarkForUpload: True dmi.bios.date: 01/08/2021 dmi.bios.release: 1.11 dmi.bios.vendor: Dell Inc. dmi.bios.version: 1.11.2 dmi.board.name: 0XMC3F dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 10 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvr1.11.2:bd01/08/2021:br1.11:svnDellInc.:pnPrecision7540:pvr:rvnDellInc.:rn0XMC3F:rvrA00:cvnDellInc.:ct10:cvr: dmi.product.family: Precision dmi.product.name: Precision 7540 dmi.product.sku: 0926 dmi.sys.vendor: Dell Inc. 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