GeraltOfTrivia

The reason that the OPi1+ doesn't clock higher than 1,48 GHz with the recent kernel versions isnt (just) the cpu opp table itself,
the entries for 1,8 GHz (and even 1,6 GHz in 5.4.20) exist.
The problem is that in the DTB, the max microvolt value for dcdca or vdd-cpu is lower than what's needed for the cpu to switch to 1,6 GHz or higher.
 
dcdca { regulator-always-on; regulator-min-microvolt = <0xc5c10>; regulator-max-microvolt = <0x107ac0>; (1080 mV) regulator-name = "vdd-cpu"; phandle = <0x6>; } opp@1640000000 { opp-hz = <0x0 0x61c06a00>; opp-microvolt = <0x11b340 0x11b340 0x11b340>; (1160 mV) clock-latency-ns = <0x3b9b0>; }; opp@1800000000 { clock-latency-ns = <0x3b9b0>; opp-hz = <0x0 0x6b49d200>; opp-microvolt-speed0 = <0x11b340>; opp-microvolt-speed1 = <0x10c8e0>; (1100 mV) opp-microvolt-speed2 = <0x10c8e0>; }; I tried this myself with my OPi1+ with kernel 5.5.0 by raising regulator-max-microvolt to 0x11b340 (1160 mV) and it successfully clocked to 1,8 GHz. YMMV. Sorry if this has already been mentioned elsewhere.

Sorry to necro an old thread, but I didn't find a more suitable one and I didn't want to start a new one. 
Anyway, to the point.
When I install or build any of the Armbian dev/nightly images with kernel 5.x, the sdcard is practically unusable after the installation. 
hdparm shows read/write speeds of max. 5 MB/sec. The reason is that unless the bus-width for mmc@4020000 is explicitly set to 4 bits in 
sun50i-h6-orangepi-one-plus.dtb mmc@4020000 { compatible = "allwinner,sun50i-h6-mmc", "allwinner,sun50i-a64-mmc"; reg = <0x4020000 0x1000>; clocks = <0x2 0x43 0x2 0x40>; clock-names = "ahb", "mmc"; resets = <0x2 0x12>; reset-names = "ahb"; interrupts = <0x0 0x23 0x4>; status = "okay"; #address-cells = <0x1>; #size-cells = <0x0>; pinctrl-names = "default"; pinctrl-0 = <0xb>; vmmc-supply = <0xc>; bus-width = <0x4>; cd-gpios = <0xd 0x5 0x6 0x1>; phandle = <0x2f>; }; the bus width defaults to 1 bit as seen in 
root@orangepi:~# cat /sys/kernel/debug/mmc0/ios clock: 50000000 Hz actual clock: 50000000 Hz vdd: 21 (3.3 ~ 3.4 V) bus mode: 2 (push-pull) chip select: 0 (don't care) power mode: 2 (on) bus width: 0 (1 bits) timing spec: 2 (sd high-speed) signal voltage: 0 (3.30 V) driver type: 0 (driver type B) which practically cripples the SD card interface. By default there is no bus-width entry in sun50i-h6-orangepi-one-plus.dtb for mmc@4020000. I don't know if this is Armbian specific or not or if this has been mentioned again, I just thought I'd share my findings in case this helps someone.