[Bug 105725] WARNING: CPU: 0 PID: 487 at drivers/gpu/drm/amd/amdgpu/../display /dc/gpio/gpio_base.c:64 dal_gpio_open_ex+0xc/0x30 [amdgpu]

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=105725

--- Comment #8 from Marc Thomas <marc at dragonfly.plus.com> ---
After some testing/experimentation/and scouring the internet, I've found that
blacklisting modules gpio_amdpt (gpio-amdpt.ko) & pinctrl_amd (pinctrl-amd.ko)
greatly reduce the likelihood of the gpio_base.c:64 & gpio_service.c:488 dmesg
warnings. I suspect some kind of race condition during boot as the modules may
load in any order.

In Slackware-current I think pinctrl_amd was compiled in, so I had to change
the Kernel config and re-compile:

-CONFIG_PINCTRL_AMD=y
+CONFIG_PINCTRL_AMD=m

The blacklist was achieved by creating this file:
root at deepthought:~# cat /etc/modprobe.d/gpio_amdpt.conf 
blacklist gpio_amdpt
blacklist pinctrl_amd


NB: I found that once I'd had these kernel warnings I needed to reset the
hardware (front panel reset button or power cycle) to clear them, even with the
blacklist in place. A reboot didn't seem to be enough.

Finally, I do still get this warning (in 4.18-rc6 & 4.17.10), but I think the
cause is something else:

root at deepthought:~# dmesg | grep WARNING
[    9.260098] WARNING: CPU: 15 PID: 1138 at
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm_mst_types.c:88
dm_dp_aux_transfer+0xa5/0xb0 [amdgpu]
[    9.260163] WARNING: CPU: 4 PID: 1142 at
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm_mst_types.c:88
dm_dp_aux_transfer+0xa5/0xb0 [amdgpu]

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