Why is SDR104 disabled?

@Lili : https://gitlab.com/rk-vendor/rk/kernel/blob/develop-4.4/arch/arm64/boot/dts/rockchip/rk3399-rock960-model-c.dts#L335
(it is the same for all 3 boards)

Is there a reason why this is disabled?

The author of this thread apparently was successful (although his writing is very poor) at getting much higher transfer speed with SDR104 enabled;

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I don’t know. I need help from the driver engineer.

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Bumping up as this is very important.
I don’t know how this is set up, but if there is down-compatibility, the maximum value should be used.
Or at least selectable (at uboot installation?).

I have great microSD card and I can’t use it with full speed. Really annoying.

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As for microSD the speed is too low, the same is for USB 3.0 pendrive.

Guys, please sort it out.

What’s your sd card model? We disable the UHS for compatibility reason.

Again, if the USB3.0 pendrive is too slow, post the model number and the speed on PC. Which usb3 port do you connect it on ROCK Pi 4?

SD card is Samsung EVO Plus 64GB.
Pendrive is Wilk GoodRam 64GB Mimic. There were days when on Windows 10 this pendrive had great speeds (80-120 MB/s write), now I tested and max write is 35 MB/s. M$ must changed sth in driver or else for these pendrives.

USB 3.0 I’ve tested in Rock on both blue ports. Now pendrive is in the lower port, closer to the board and there are no changes to the speed - it is low.

Sorry for late response, I was in work.

EDIT: mounted pendrive gets 32.9 MB/s write ; mounted microSD card gets 16.9 MB/s - both ext4, writing from /dev/zero.

Jack, I’ve edited my previous post and adding some info here: this pendrive is UMM3, not Mimic.
Goodram has changed the pendrives some time ago and I have both Mimic and UMM3 which should be the same, but aren’t. They downgraded the speed of RW and UMM3 (newer) is limited, where Mimic (older) shouldn’t be.

I will test Mimic now for the speeds and if sth unusual occurs, I will let you know.

EDIT:
Seems like all Goodram pendrives have low speeds so they are not applicable here.
I’ve tested them on Windows and speeds are R45/W24 MB/s.

I’ve tested also SanDisk Extreme U100 USB 3.0 32GB and it is getting these write speeds:
87.7, 81.6 and 89.5 MB/s.
On Windows this pendrive gets R227/W115 MB/s.

So it is pendrives issue, not Rock Pi related hardware/software/kernel.

Still good microSD does not achieve nominal speeds (max 16.3 MB/s).

Crucial MX500 1 TB via LogiLink AU0012A: 230-260 MB/s linear read, 155-177 MB/s linear write (byte 0).

This drive on Windows gets: read 437.5 / write 436.9 MB/s (CrystalDiskMark 6.0.2 x64, 3 GB test file).