These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 2.76 s (backtrack: 0/20).

[ebuild  N     ] sys-libs/mtdev-1.1.7::gentoo  295 KiB
[ebuild  N     ] gui-libs/display-manager-init-1.1.2-r3::gentoo  0 KiB
[ebuild  N     ] media-fonts/font-util-1.4.2::gentoo  150 KiB
[ebuild  N     ] x11-base/xorg-drivers-21.1-r2::gentoo  INPUT_DEVICES="evdev vmmouse -elographics -joystick -libinput -synaptics -void -wacom" VIDEO_CARDS="vesa -amdgpu -ast -dummy -fbdev (-freedreno) (-geode) -i915 -intel -mga -nouveau -nvidia -qxl -r128 -radeon -radeonsi -siliconmotion (-tegra) (-vc4)" 0 KiB
[ebuild  N     ] x11-libs/libXfont2-2.0.9::gentoo  USE="bzip2 truetype -doc" 468 KiB
[ebuild  N     ] x11-apps/xauth-1.1.5::gentoo  162 KiB
[ebuild  N     ] x11-libs/libpciaccess-0.19::gentoo  USE="zlib -static-libs" 64 KiB
[ebuild  N     ] x11-libs/libxkbfile-1.2.0::gentoo  57 KiB
[ebuild  N     ] x11-apps/iceauth-1.0.11::gentoo  138 KiB
[ebuild  N     ] x11-misc/xbitmaps-1.1.4::gentoo  112 KiB
[ebuild  N     ] x11-misc/xkeyboard-config-2.48::gentoo  USE="-test" 931 KiB
[ebuild  N     ] x11-libs/libxcvt-0.1.3::gentoo  10 KiB
[ebuild  N     ] media-libs/libepoxy-1.5.10-r3::gentoo  USE="X -test" 325 KiB
[ebuild  N     ] dev-libs/libevdev-1.13.7::gentoo  USE="-doc -test" 462 KiB
[ebuild     U  ] x11-libs/libdrm-2.4.134::gentoo [2.4.131::gentoo] USE="-doc -test -tools -udev -valgrind" VIDEO_CARDS="amdgpu* vmware (-exynos) (-freedreno) -intel -nouveau (-omap) -radeon (-tegra) (-vc4) (-vivante)" 427 KiB
[ebuild  N     ] x11-apps/xrdb-1.2.3-r2::gentoo  141 KiB
[ebuild  N     ] x11-apps/xinit-1.4.4::gentoo  USE="-twm" 159 KiB
[ebuild  N     ] x11-apps/xkbcomp-1.5.0-r2::gentoo  243 KiB
[ebuild  N     ] x11-base/xorg-server-21.1.25:0/21.1.25::gentoo  USE="udev xorg -debug -elogind -minimal (-selinux) -suid (-systemd) -test -unwind -xcsecurity -xephyr -xnest -xvfb" 4968 KiB
[ebuild  N     ] x11-drivers/xf86-input-vmmouse-13.2.0::gentoo  279 KiB
[ebuild  N     ] x11-drivers/xf86-video-vesa-2.6.0::gentoo  270 KiB
[ebuild  N     ] x11-drivers/xf86-input-evdev-2.11.0::gentoo  344 KiB
[ebuild  N     ] x11-drivers/xf86-video-amdgpu-25.0.0-r1::gentoo  USE="-udev" 74 KiB

Total: 23 packages (1 upgrade, 22 new), Size of downloads: 10069 KiB

The following USE changes are necessary to proceed:
 (see "package.use" in the portage(5) man page for more details)
# required by x11-drivers/xf86-video-amdgpu-25.0.0-r1::gentoo
# required by =x11-drivers/xf86-video-amdgpu-25.0.0-r1 (argument)
>=x11-libs/libdrm-2.4.134 video_cards_amdgpu