Created attachment 297443 [details] 5.13-rc6 dmesg log I notice the Broadcom genet fails to attach ethernet PHY on Raspberry Pi 4B sometimes (more then 50%) when I test kernel 5.13-rc6, also tested 5.11. It shows errors in the kernel message: [ 10.615778] bcmgenet fd580000.ethernet: GENET 5.0 EPHY: 0x0000 ... [ 11.585741] could not attach to PHY [ 11.585790] bcmgenet fd580000.ethernet eth0: failed to connect to PHY The full dmesg as the attachment.
Created attachment 297445 [details] The kernel 5.13-rc6 build config
Created attachment 297519 [details] Add debug messages based on 5.13-rc6 Now, the ethernet is not detected as usual and showing the log $ dmesg | grep -E "(net|phy|PHY|mdio)" [ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd083] [ 0.000000] arch_timer: cp15 timer(s) running at 54.00MHz (phys). [ 0.038269] audit: initializing netlink subsys (disabled) [ 0.072009] usb_phy_generic phy: supply vcc not found, using dummy regulator [ 0.223554] libphy: Fixed MDIO Bus: probed [ 0.226192] hns3: Hisilicon Ethernet Network Driver for Hip08 Family - version [ 0.226390] igb: Intel(R) Gigabit Ethernet Network Driver [ 0.240676] 9pnet: Installing 9P2000 support [ 10.353067] bcmgenet fd580000.ethernet: GENET 5.0 EPHY: 0x0000 [ 11.470402] libphy: bcmgenet MII bus: probed [ 11.509851] of_mdio_find_device: does not find ethernet-phy@1 on mdio bus [ 11.509867] of_phy_find_device: mdio does not find ethernet-phy@1 [ 11.509874] bcmgenet fd580000.ethernet eth0: of_phy_connect: dn full_name ethernet-phy@1 [ 11.509884] could not attach to PHY [ 11.509888] bcmgenet fd580000.ethernet eth0: failed to connect to PHY [ 11.657266] unimac-mdio unimac-mdio.-19: Broadcom UniMAC MDIO bus Tracing the code by following the debug message, I understand that genet tries to find out the MDIO device corresponding to genet on the MDIO bus. But, it fails at first time, because unimac-mdio from mdio-bcm-unimac module has not prepared it for genet, yet.
Created attachment 297521 [details] The full dmesg with the debug message of comment #2
Created attachment 297523 [details] The device tree decoded from bcm2711-rpi-4-b.dtb The dependency relationship can be found in bcm2711-rpi-4-b's device tree. ethernet@7d580000 { compatible = "brcm,bcm2711-genet-v5"; ... phy-mode = "rgmii-rxid"; mdio@e14 { compatible = "brcm,genet-mdio-v5"; reg = <0xe14 0x08>; reg-names = "mdio"; #address-cells = <0x00>; #size-cells = <0x01>; ethernet-phy@1 { reg = <0x01>; phandle = <0x27>; }; }; }; $ git grep "brcm,genet-mdio-v5" Documentation/devicetree/bindings/net/brcm,bcmgenet.txt: "brcm,genet-mdio-v3", "brcm,genet-mdio-v4", "brcm,genet-mdio-v5", the version Documentation/devicetree/bindings/net/brcm,unimac-mdio.txt: "brcm,genet-mdio-v3", "brcm,genet-mdio-v4", "brcm,genet-mdio-v5" or arch/arm/boot/dts/bcm2711.dtsi: compatible = "brcm,genet-mdio-v5"; drivers/net/mdio/mdio-bcm-unimac.c: { .compatible = "brcm,genet-mdio-v5", },
According to comment #2 ~ #4, the unimac-mdio comes too late for genet, or system is too late to load mdio-bcm-unimac module. So, I re-probe genet module manually again. The ethernet is detected as following log and works correctly. [ 116.210987] bcmgenet fd580000.ethernet: GENET 5.0 EPHY: 0x0000 [ 116.226345] libphy: bcmgenet MII bus: probed [ 116.298480] unimac-mdio unimac-mdio.-19: Broadcom UniMAC MDIO bus [ 116.350126] of_mdio_find_device: going to get ethernet-phy@1's mdio device [ 116.350146] of_phy_find_device: going to get ethernet-phy@1's phy_device [ 116.350154] bcmgenet fd580000.ethernet eth0: of_phy_connect: dn full_name ethernet-phy@1 [ 116.350164] bcmgenet fd580000.ethernet eth0: of_phy_connect: going to connect ethernet-phy@1 directly [ 116.352460] bcmgenet fd580000.ethernet: configuring instance for external RGMII (RX delay) [ 116.355594] bcmgenet fd580000.ethernet eth0: Link is Down [ 118.402544] bcmgenet fd580000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx The full dmesg is the same as comment #3
Could you try one of these two approaches: diff --git a/drivers/net/mdio/mdio-bcm-unimac.c b/drivers/net/mdio/mdio-bcm-unimac.c index bfc9be23c973..53fecb53cd65 100644 --- a/drivers/net/mdio/mdio-bcm-unimac.c +++ b/drivers/net/mdio/mdio-bcm-unimac.c @@ -349,6 +349,7 @@ static struct platform_driver unimac_mdio_driver = { .name = UNIMAC_MDIO_DRV_NAME, .of_match_table = unimac_mdio_ids, .pm = &unimac_mdio_pm_ops, + .probe_type = PROBE_FORCE_SYNCHRONOUS, }, .probe = unimac_mdio_probe, .remove = unimac_mdio_remove, or preferably: diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c b/drivers/net/ethernet/broadcom/genet/bcmgenet.c index fcca023f22e5..41f7f078cd27 100644 --- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c @@ -4296,3 +4296,4 @@ MODULE_AUTHOR("Broadcom Corporation"); MODULE_DESCRIPTION("Broadcom GENET Ethernet controller driver"); MODULE_ALIAS("platform:bcmgenet"); MODULE_LICENSE("GPL"); +MODULE_SOFTDEP("pre: mdio-bcm-unimac"); and let me know if either work?
(In reply to Florian Fainelli from comment #6) > Could you try one of these two approaches: > > diff --git a/drivers/net/mdio/mdio-bcm-unimac.c > b/drivers/net/mdio/mdio-bcm-unimac.c > index bfc9be23c973..53fecb53cd65 100644 > --- a/drivers/net/mdio/mdio-bcm-unimac.c > +++ b/drivers/net/mdio/mdio-bcm-unimac.c > @@ -349,6 +349,7 @@ static struct platform_driver unimac_mdio_driver = { > .name = UNIMAC_MDIO_DRV_NAME, > .of_match_table = unimac_mdio_ids, > .pm = &unimac_mdio_pm_ops, > + .probe_type = PROBE_FORCE_SYNCHRONOUS, > }, > .probe = unimac_mdio_probe, > .remove = unimac_mdio_remove, The bug still can be reproduced with this approach.
(In reply to Florian Fainelli from comment #6) > Could you try one of these two approaches: > > diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c > b/drivers/net/ethernet/broadcom/genet/bcmgenet.c > index fcca023f22e5..41f7f078cd27 100644 > --- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c > +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c > @@ -4296,3 +4296,4 @@ MODULE_AUTHOR("Broadcom Corporation"); > MODULE_DESCRIPTION("Broadcom GENET Ethernet controller driver"); > MODULE_ALIAS("platform:bcmgenet"); > MODULE_LICENSE("GPL"); > +MODULE_SOFTDEP("pre: mdio-bcm-unimac"); MODULE_SOFTDEP("pre: mdio-bcm-unimac") solves this issue. Tracing the code by following the debug message in comment #2, I learned the path bcmgenet_mii_probe()'s of_phy_connect() -> of_phy_find_device() -> of_mdio_find_device() -> bus_find_device_by_of_node(). And, bus_find_device_by_of_node() cannot find the device on the mdio bus. So, I traced bcm2711-rpi-4-b's device tree to find out which one is the mdio device and why it has not been prepared ready on the mdio bus for genet. Then, I found out it is mdio-bcm-unimac module as mentioned in comment #4. Also, noticed "unimac-mdio unimac-mdio.-19: Broadcom UniMAC MDIO bus" comes after "bcmgenet fd580000.ethernet eth0: failed to connect to PHY" in the log. With these findings, I try to re-modprobe genet module again. The ethernet on RPi 4B works correctly! Also, noticed mdio-bcm-unimac module is loaded before I re-modprobe genet module. Therefore, I try to make mdio-bcm-unimac built in kernel image, instead of a module. Then, genet always can find the mdio device on the bus and the ethernet works as well. Consequently, the idea, loading mdio-bcm-unimac module earlier than genet module comes in my head! But, I don't know the key word "MODULE_SOFTDEP" until Florian's guide. I think this is like the module dependency situation mentioned in commit 11287b693d03 ("r8169: load Realtek PHY driver module before r8169") [1]. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=11287b693d03830010356339e4ceddf47dee34fa
Place some reference here: * MODULE_SOFTDEP is defined in include/linux/module.h [1] * modprobe.d has an example: [2] Assume "softdep c pre: a b post: d e" is provided in the configuration. Running "modprobe c" is now equivalent to "modprobe a b c d e" without the softdep. [1] https://elixir.bootlin.com/linux/v5.13-rc7/source/include/linux/module.h#L170 [2] https://man7.org/linux/man-pages/man5/modprobe.d.5.html
I can make a new patch with the approach MODULE_SOFTDEP("pre: mdio-bcm-unimac"). Florian, may I have your singed-off-by in the commit message? Or, you prefer tag the SoB by yourself?
Fixed by the commit 19938bafa7ae ("net: bcmgenet: Add mdio-bcm-unimac soft dependency"). https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=19938bafa7ae8fc0a4a2c1c1430abb1a04668da1
(In reply to Jian-Hong Pan from comment #11) > Fixed by the commit 19938bafa7ae ("net: bcmgenet: Add mdio-bcm-unimac soft > dependency"). > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/ > ?id=19938bafa7ae8fc0a4a2c1c1430abb1a04668da1 Hello ! I have the same problem on my raspberry pi 400 but I'm new to this and I don't understand how to clean it. How git diff works ? What is it doing ? It's downloading something ? Thx for your answer and sorry ton up this topic !