CPU mis identified, need to force workaround

[Peter D.]

This is probably an upstream bug, but this looks like the first pont of contact.

I have a TV tuner card that works with old CPUs but fails with new CPUs that are "too fast". This is a known problem and there is a workaround for it. The workaround is automatically applied when a "fast" CPU is detected, but not mine.

The workaround can be forced by adding this file to /etc/modprobe.d

# /etc/modprobe.d/Hauppauge-WinTV-QuadHD.conf
# 0 means force workaround off
# 1 means auto detect troublsome CPUs
# 2 means force workaround on
options cx23885 dma_reset_workaround=2

My CPU is only a Ryzen 3 2200G. I will attach the output of cpuid, minus the serial number.

ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: linux-image-5.3.0-19-generic 5.3.0-19.20
ProcVersionSignature: Ubuntu 5.3.0-19.20-generic 5.3.1
Uname: Linux 5.3.0-19-generic x86_64
ApportVersion: 2.20.11-0ubuntu8.1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: psd 1263 F.... pulseaudio
 /dev/snd/controlC1: psd 1263 F.... pulseaudio
CurrentDesktop: XFCE
Date: Thu Oct 31 10:34:56 2019
InstallationDate: Installed on 2019-10-21 (9 days ago)
InstallationMedia: Xubuntu 19.10 "Eoan Ermine" - Release amd64 (20191017)
IwConfig:
 lo no wireless extensions.

 enp12s0 no wireless extensions.
MachineType: To Be Filled By O.E.M. To Be Filled By O.E.M.
ProcEnviron:
 LANGUAGE=en_AU:en
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_AU.UTF-8
 SHELL=/bin/bash
ProcFB: 0 nouveaudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.3.0-19-generic root=UUID=a506aa84-ff7a-48c6-8121-fae57b937f9c ro quiet splash
RelatedPackageVersions:
 linux-restricted-modules-5.3.0-19-generic N/A
 linux-backports-modules-5.3.0-19-generic N/A
 linux-firmware 1.183.1
RfKill:
 0: hci0: Bluetooth
  Soft blocked: no
  Hard blocked: no
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 07/02/2019
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: P3.40
dmi.board.name: B450 Pro4
dmi.board.vendor: ASRock
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: To Be Filled By O.E.M.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrP3.40:bd07/02/2019:svnToBeFilledByO.E.M.:pnToBeFilledByO.E.M.:pvrToBeFilledByO.E.M.:rvnASRock:rnB450Pro4:rvr:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.:
dmi.product.family: To Be Filled By O.E.M.
dmi.product.name: To Be Filled By O.E.M.
dmi.product.sku: To Be Filled By O.E.M.
dmi.product.version: To Be Filled By O.E.M.
dmi.sys.vendor: To Be Filled By O.E.M.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.

[Peter D. (0123peter)]

My guess is that
.../drivers/media/pci/cx23885/cx23885-core.c
is important and maybe my IOMMU, but I don't feel competent to patch the code myself. Nor am I certain that "15d1" is the magic number for Raven Ridge APUs.

psd@myth:~$ lspci -s 0:00.2
00:00.2 IOMMU: Advanced Micro Devices, Inc. [AMD] Device 15d1