Radxa Rock5 RK3588 SBC: PCIe lanes clarification

It is still true that big GPU cards don’t work ?
And is it possible to ask RockChip if they can fix it or if they can fix it in next silicon release?

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@mIIsko, Read what does PCIe BAR means and it’s size for ARM.

Also. You do understand, that’s there literally zero performance gain from big GPU since CPU will be bottleneck?

I bought this https://www.youtube.com/watch?v=EV_kIwmgVMM
And I can connect big GPU over M.2 and I don’t see any bottleneck on CPU side :slight_smile:
But I can use it for lots of fun stuff :slight_smile:

Just to clarify… you’re talking about native SATA here, right?

So this adapter board will go into the M.2 Key E slot to switch the Combo PIPE PHY from PCIe to SATA?


You really have no idea what is x86_64 and arm64 and what the difference between them?

We are talking about watermelon and that you cant fry it and you saying “hey guys i bought meat and can fry it”

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Yes, with a device tree overlay, we can change the combo PHY to SATA mode:


Is there a module that converts one M2 into 2 M2?

There’s either PCIe Gen2 x1 or SATA in this M.2 key E slot so such a ‘module’ can not be a mechanical converter but needs to be one of those:

  • a PCIe switch that can turn one PCIe lane into multiple (sharing bandwidth, higher latency)
  • a PCIe controller e.g. providing additional SATA ports (ASM1061 for example to name the cheapest possible)
  • a SATA port multiplier like JMB575 that could turn the single SATA lane into 5 upstream SATA ports (I forgot whether we have already data if Rockchip’s recent SoCs support SATA PM or not and whether FIS-based switching or CBS but at least the RK3588 TRM states ‘Port Multiplier with FIS-based switching’ so this should be fine and with the SATA converter and a JMB575 we should be able to attach 5 pieces of spinning rust or SSDs to Rock 5B)

But due to space constraints none of this works in the M.2 2230 form factor so without an extender cable you’re lost.

is it also possible through combophy to enable sata through the usb3 port ? that way you can still have a option for wifi and storage through the pcie lanes .

would be nice when a vendor replace the hdmi board in a portable monitor with a rk3588 would be a nice streamer setup :wink:

It would be really great if you could ASAP purchase a JMB575 SATA port multiplier like this one and test with 2 SATA devices whether they can be seen or not. If you do so please provide dmesg output here so we can see whether FIS-based switching or CBS happens.

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Do you want a couple of those as you can have em free if you send address?

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If you was asking me: no, thank you. I lack the M.2 SATA converter and those boards look like JMB321 which IIRC doesn’t support FIS-based switching so we could not check RK3588’s capabilities.

Asides that why not let the manufacturer do this since they’ve tested already with SATA for sure and all they lack is such a JMB575 board for a few bucks :slight_smile:

JMB321 I think is sata II (The boards say sata III) but hey, who cares it was just an offer, they are gathering dust though.

@jack investigation/discussion why we’re stuck on CBS already started: https://forum.odroid.com/viewtopic.php?p=352738#p352738

Would be great if you can join the efforts maybe asking Rockchip whether there’s a missing DT property or something that needs to be tweaked in the kernel to get from AHCI_HFLAG_NO_FBS to AHCI_HFLAG_YES_FBS :wink:

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I asked Rockchip about the issue and posted answer in ODROID forum (since there are people who actually could test). Still hoping you get such a JMB575 thingy to try out with ROCK 5B and the aforementioned patches.


@jack: now it’s time for Radxa to get their things done.

We as community showed how important FIS-based switching vs. CBS is now it’s your turn to fix DT/kernel. :slight_smile:


Sorry, confused a bit. Will M.2 M-key to SATA adapter work? Like this:

Should work as expected. At least JMB585 is confirmed to work with RK3568: https://forum.odroid.com/viewtopic.php?f=212&t=44318

But you should check this thread (it’s not about NVMe issues but PCIe link training which could affect every PCIe card in the M.2 key M slot).

Haven’t tried one but as TK says confirmed to work on RK3568 which is Pcie3.0 x2 lanes which also is the JMB585 from memory.
RK3588 is Pcie3.0 x4 lanes so has surplus.

Has anyone actually tried a bifurcation adapter? I bought an m2 to full size (x16) adapter then used this to try to bifurcate into two 2x lanes slots.

Didn’t work, only the first slot would work, tested with two cards that were known to work. Dmesg did show that it was operating at x2 speeds in the one slot that would detect. If you have an adapter works I’d love a link to it.