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About linux : Issue-with-binding-platform-driver-to-the-platform-device

Question Detail

I want to make work mt7622 soc’s ethernet controller and faced with this issue. I’ve compiled mtk_soc_eth driver as mkt_eth module and I have an entry in mt7622-bananapi-bpi-r64.dts device tree for device, compatible with driver.

During boot this module is loaded into system automatically (I think after mounting rootfs):

[root@nixos:~]# lsmod | grep mtk_eth
mtk_eth                69632  0
dsa_core               98304  1 mtk_eth

And it seems registered as platform driver:

[root@nixos:~]# ls /sys/bus/platform/drivers/mtk_soc_eth
bind  module  uevent  unbind

Also after boot I have an platform device:

[root@nixos:~]# ls /sys/bus/platform/devices/1b100000.ethernet

However they are not binded for some reason. Moreover, when I try to bind them manually, I get an error:

[root@nixos:~]# echo '1b100000.ethernet' > /sys/bus/platform/drivers/mtk_soc_eth/bind
-bash: echo: write error: Resource temporarily unavailable

How can I understand why ethernet device doesn’t bind with driver?

Question Answer

Well, it seems that I figured out where is the problem. It seems that linux kernel have rich debug options) I’ve enabled dynamic debug to track which happens inside __driver_probe_device https://github.com/torvalds/linux/blob/master/drivers/base/dd.c#L730 function:

[root@nixos:~]# echo 'file dd.c +p'>/sys/kernel/debug/dynamic_debug/control
[root@nixos:~]# echo 'file core.c +p'>/sys/kernel/debug/dynamic_debug/control

And then tried to bind device driver and device:

[root@nixos:~]# echo '1b100000.ethernet' >/sys/bus/platform/drivers/mtk_soc_eth/bind
-bash: echo: write error: Resource temporarily unavailable
[root@nixos:~]# dmesg -T | tail
[Sat Jan  1 00:03:27 2000] bus: 'platform': __driver_probe_device: matched device 1b100000.ethernet with driver mtk_soc_eth
[Sat Jan  1 00:03:27 2000] platform 1b100000.ethernet: error -EPROBE_DEFER: supplier 1b000000.syscon not ready

It seems that one of the dependent devices (1b000000.syscon) is not ready (at the same time /sys/bus/platform/devices/1b100000.ethernet/waiting_for_supplier was still 0 for some reason). I need to load clk-mt7622-eth driver as well.

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