I applied these commands:
fdtput --type s /boot/dtb-4.12.13-300.fc26.armv7hl/bcm2837-rpi-3-b.dtb /soc/spi@7e204000 status "okay"

fdtput --type s /boot/dtb-4.12.13-300.fc26.armv7hl/bcm2837-rpi-3-b.dtb /soc/spi@7e215080 status "okay"
fdtput --type s /boot/dtb-4.12.13-300.fc26.armv7hl/bcm2837-rpi-3-b.dtb  /soc/spi@7e2150c0 status "okay"

And now I see spi_bcm2835 and spi_bcm2835aux modules started, after the reboot. But I can't see my /dev/spi* devices. 

Do you have an idea of the missing step? 

[root@raspchr-fed26 device-tree]# dmesg | grep spi
[   93.646629] spi-bcm2835 3f204000.spi: no tx-dma configuration found - not using dma mode
[root@raspchr-fed26 device-tree]# 

I still see other devices: 

Do I need to activate them ? 

Thanks for your help. 

2017-09-16 22:53 GMT+02:00 christophe pages <pageschrist@gmail.com>:
Thanks for your answer, Yes I added these 2 lines in the config.txt file like for the raspbain . 
So What do I have to do with the dtb files. I see nothing regarding the spi. 
Do I still have to use the config.txt file ? 
Thanks for your help.

2017-09-16 14:57 GMT+02:00 Peter Robinson <pbrobinson@gmail.com>:
On Sat, Sep 16, 2017 at 1:33 PM, christophe pages <pageschrist@gmail.com> wrote:
> Hello,
> I try to activate the spi on my raspberry3 using a fedora 26.
> I tried these options:
> device_tree_param=spi=on
> dtoverlay=spi-bcm2708

Did you add that to config.txt? That way of doing it is specific to
Rasspian, the driver in Fedora is the upstream driver which is
spi-bcm2835aux and you'll need to either edit the dtb to enable it or
use a DT overlay as it's disabled by default.

> I use this kernel:
> 4.12.5-300.fc26.armv7hl
> I see that the support in kernel seems already inside:
> # CONFIG_SPI_DEBUG is not set
> But I never see the devices /dev/spi* appearing.
> I can't see any messages regarding spi in dmesg.
> I tested with a raspbian and I see them correctly.
> I think I miss somethiing.
> Could you help.
> Thanks.
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