fix for hdac0: Command timeout on address, with the i915 driver and intel

Is there a way to trigger that timeout error intentionally? I see it sometimes in dmesg (Dell Latitude 5591, Intel UHD 630 with HDMI screen, FreeBSD 14.1)

I'm also curious about the power well connection; how was that figured out, and what exactly is Intel's definition of what power well does and controls? I saw a kernel option on Linux about it but couldn't figure out what it did, but it sounds like something I'd either want all-on or off no dynamics. i915_disable_power_well=0 looks like it's telling i915 to not disable power well(s), but it sounds like that/those would be on by-default?

Edit: sysctl -d is nice, and 0 sounds good to me!

Code: 
compat.linuxkpi.i915_disable_power_well: Disable display power wells when possible (-1=auto [default], 0=power wells always on, 1=power wells disabled when possible)

Although, what one is better to use between hw.i915kms.disable_power_well and compat.linuxkpi.i915_disable_power_well?

Edit: Seems hw.i915kms is preferred! https://wiki.freebsd.org/Graphics#Debugging_tips

Starting with FreeBSD 13 you can use the direct driver sysctls, the compat.linuxkpi will be removed at one point.

% sysctl -d hw.i915kms
Click to expand...
 
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