In fact, rk3328 and rk3399 both seem to have the same set of the SD/eMMC contollers. Namely, and it looks the first two instances are one IP, and the third is another. They are called SDMMC, SDIO and EMMC respectively. SDIO is specifically made to serve SDIO protocol, but both of these IPs look as capable of managing both SD memory cards and eMMC modules. The SDMMC looks a bit older design, it can do DDR50 but can't SDR104. EMMC does support all the UHS-I modes. I guess the SD card cage is routed to SDMMC, on both boards and eMMC module - to EMMC, right?
The question is does anybody really know here of why UHS-I doesn't work on rock64, and i guess the same goes to rockpro64? Nobody is interested in that? Of course, there is eMMC, USB3, and even frigging PCIe for NVMe SSDs, but does it validate screwing up the SD interface? It is already there, the SoC internals are ready for UHS-I speed modes, that could at least double the throughput on SD cards, that still play the special role of installation media so often on SBCs! Unfortunately I am too far away of trying it by myself. The voltage switch sequence requires supporting interrupts and timers. It's not working on my project for these boards yet.
I own rock64 but I don't have rockpro64. But Odroid N1 with the same rk3399 does UHS-I modes! Renegade as well. Maybe some of you own an rk3328 set top box, maybe there, UHS-I is implemented, do you have numbers for those? Share please. Rockchip for incomprehensible reasons doesn't want to release the full manual on rk3328. 
Please, whoever authoritative, explain clearly, is this lack of UHS-I on rock64, rockpro64 due to the software (linux) support or it hasn't been done properly on the board level?
I read the rk3399 manual. EMMC IP is crappily documented, SDMMC is much better. There is a lot of guidances, there is a chapter for voltage switching as well. so cool. But in the chapter, there is a funny thing, the problem is they decided to be funny in a wrong place. On the most interesting and serious moment, some mystery surfaces - when it comes to the real voltage switch, the manual says: "write Voltage Register", on the timing figure, it's called "register 74". Ok, but what is that? Of what module this register is? Does anybody know this?
PS. Even A64 of Pine64 is capable of UHS-I according to the Allwinner manual.
The question is does anybody really know here of why UHS-I doesn't work on rock64, and i guess the same goes to rockpro64? Nobody is interested in that? Of course, there is eMMC, USB3, and even frigging PCIe for NVMe SSDs, but does it validate screwing up the SD interface? It is already there, the SoC internals are ready for UHS-I speed modes, that could at least double the throughput on SD cards, that still play the special role of installation media so often on SBCs! Unfortunately I am too far away of trying it by myself. The voltage switch sequence requires supporting interrupts and timers. It's not working on my project for these boards yet.
I own rock64 but I don't have rockpro64. But Odroid N1 with the same rk3399 does UHS-I modes! Renegade as well. Maybe some of you own an rk3328 set top box, maybe there, UHS-I is implemented, do you have numbers for those? Share please. Rockchip for incomprehensible reasons doesn't want to release the full manual on rk3328. Please, whoever authoritative, explain clearly, is this lack of UHS-I on rock64, rockpro64 due to the software (linux) support or it hasn't been done properly on the board level?
I read the rk3399 manual. EMMC IP is crappily documented, SDMMC is much better. There is a lot of guidances, there is a chapter for voltage switching as well. so cool. But in the chapter, there is a funny thing, the problem is they decided to be funny in a wrong place. On the most interesting and serious moment, some mystery surfaces - when it comes to the real voltage switch, the manual says: "write Voltage Register", on the timing figure, it's called "register 74". Ok, but what is that? Of what module this register is? Does anybody know this?
PS. Even A64 of Pine64 is capable of UHS-I according to the Allwinner manual.
ANT - my hobby OS for x86 and ARM.
