Thames [Radeon HD 7550M/7570M/7650M]: drm.ko in lieu of radeonkms, with xf86-video-ati (was: need some advice for video output)

At 
<https://lists.freebsd.org/pipermail/freebsd-questions/2020-November/292156.html> 
Antonio Olivares wrote:
> Restarting the machine fixed the problem.  I removed the line from rc.conf
> and installed xf86-video-ati
> pkg and now have a good working desktop.
> Sorry for the noise.
>
> Best Regards,
>
>
> Antonio

I don't mind the noise :-)

With Thames [Radeon HD 7550M/7570M/7650M] on -CURRENT, I benefit from 
/boot/modules/drm.ko (specifically _not_ radeonkms) specified in rc.conf:

root_at_mowa219-gjp4-8570p:~ # grep -v \# /etc/rc.conf | grep kld
kldxref_enable="NO"
kldxref_clobber="NO"
kld_list="fusefs"
kld_list="/boot/modules/drm.ko"
root_at_mowa219-gjp4-8570p:~ # pkg query '%o %v %R' drm-kmod 
drm-current-kmod xf86-video-ati xf86-video-amdgpu
graphics/drm-kmod g20190710 poudriere
graphics/drm-current-kmod 5.4.62.g20201109_1 poudriere
x11-drivers/xf86-video-ati 19.1.0_3,1 FreeBSD
root_at_mowa219-gjp4-8570p:~ # date ; uname -v
Sun Nov 29 09:07:34 GMT 2020
FreeBSD 13.0-CURRENT #72 r367936: Sun Nov 22 21:46:00 GMT 2020 
root_at_mowa219-gjp4-8570p:/usr/obj/usr/src/amd64.amd64/sys/GENERIC-NODEBUG
root_at_mowa219-gjp4-8570p:~ #

Peculiar.

Background:

<https://gitter.im/FreeBSDDesktop/Lobby/archives/2020/09/21?at=5f688e2fb468994d0d41ef44> 
a suggestion to try not having |xf86-video-| anything.

<https://gitter.im/FreeBSDDesktop/Lobby/archives/2020/10/02?at=5f76efb01b444b4eafb0af7a> 
success after ceasing use of kld_list="radeonkms" in rc.conf.

HW probe of HP EliteBook 8570p #1f3fa432dc
<https://bsd-hardware.info/index.php?probe=1f3fa432dc>