How to Use Sata port multiplier?

I recently got banana pi m2u and I wanted to make a small home nas server with the old hard drives lying around. So I brought Sata port multiplier too. I am using Raspbian Jiessie ( kernel version - 3.10.107 ) and I want know how to use sata port multiplier. I just plug it in and see it work but sadly it won’t work

I’m the same problem with bpi m2u

**pi@bpi-m2u ~]$ dmesg | grep sunxi-ahci**
**[    1.432717] sunxi-ahci sata: sata_regulator0 "vdd-sata-25"!**
**[    1.432795] sunxi-ahci sata: sata_regulator1 "vdd-sata-12"!**
**[    1.433810] sunxi-ahci sata: regulator "vdd-sata-25" voltage set: 2500000 to 2500000!**
**[    1.434749] sunxi-ahci sata: regulator "vdd-sata-12" voltage set: 1200000 to 1200000!**
**[    1.436946] sunxi-ahci sata: frequncy of module clk for AHCI: 100000000**
**[    1.436957] sunxi-ahci sata: frequncy of pll clk for AHCI: 100000000**
**[    1.500039] sunxi-ahci sata: SATA power enable do not exist!!**
**[    1.506473] sunxi-ahci sata: controller can't do PMP, turning off CAP_PMP**
**[    1.506484] sunxi-ahci sata: forcing PORTS_IMPL to 0x1**
**[    1.506538] sunxi-ahci sata: AHCI 0001.0100 32 slots 1 ports 3 Gbps 0x1 impl platform mode**
**[    1.506552] sunxi-ahci sata: flags: ncq sntf pm led clo only pio slum part ccc **
**[    1.508062] scsi0 : sunxi-ahci**

How to force PMP sata ?

I try “nano /etc/modprobe.d/ahci-sunxi.conf” with “options ahci-sunxi enable_pmp=1

I find this

I try to compile kernel PMP like module for trying…

Did it Work ? and how did you compile kernel PMP I am that not experienced with these things

Is broken, I don’t know why ? Impossible to enable PMP with old kernel. I wait for 4.9 kernel.

It’s neither broken nor you need a new kernel. You just bought a device that receives zero support.

I built the kernel with the boring simple fix, let a friend test and documented it in linux-sunxi wiki:

(just work you through the ‘R40/V40 also support port multipliers’ link there but you have to be fast since in this forum here for funny reasons posts get deleted)

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Note that after they tell you how to do it, they explain why its a bad idea.