[PATCH] arm64: dts: rockchip: rock-3a: make ethernet work

[Jonas Karlman]

On 2023-07-17 19:11, Jonas Karlman wrote:
> On 2023-07-17 09:40, Michael Riesch wrote:
>> Hi all,
>>
>> In addition to what has been already said:
>>
>> On 7/16/23 15:50, Jonas Karlman wrote:
>>> On 2023-07-15 06:49, FUKAUMI Naoki wrote:
>>>> hi,
>>>>
>>>> On 7/15/23 01:24, Jonas Karlman wrote:
>>>>> On 2023-07-14 17:46, Heiko Stuebner wrote:
>>>>>> Am Freitag, 14. Juli 2023, 08:30:27 CEST schrieb FUKAUMI Naoki:
>>>>>>> ethernet on Radxa ROCK 3A is not working by following error:
>>>>>>>
>>>>>>>   rk_gmac-dwmac fe010000.ethernet eth0: no phy at addr -1
>>>>>>>   rk_gmac-dwmac fe010000.ethernet eth0: stmmac_open: Cannot attach to PHY (error: -19)
>>>>>>>
>>>>>>> to fix this problem, align related properties with vendor kernel
>>>>>>>   https://github.com/radxa/kernel/blob/linux-5.10-gen-rkr4.1/arch/arm64/boot/dts/rockchip/rk3568-rock-3a.dts
>>>>>>>
>>>>>>> Fixes: 22a442e6586c ("arm64: dts: rockchip: add basic dts for the radxa rock3 model a")
>>>>>>> Signed-off-by: FUKAUMI Naoki <naoki at radxa.com>
>>>>>>
>>>>>> There also is a second patch in the mix adding the gmac1_clkin
>>>>>> ef9f4b4a5020 ("arm64: dts: rockchip: Add support of external clock to ethernet node on Rock 3A SBC")
>>>>>>
>>>>>> And this patch does the exact opposite as the original nodes.
>>>>>> Can someone please mention board versions? Or did the gmac1 never
>>>>>> really work in the first place?
>>
>> As far as I know all schematics versions state that the PHY produces the
>> clock (see the most recent schematics here:
>> https://dl.radxa.com/rock3/docs/hw/3a/ROCK-3A-V1.3-SCH.pdf
>> 
>> Although using the internal MAC clock works as well, using the
>> gmac1_clkin is most probably the correct way.
>>
>>>>> Ethernet have worked and probably still works booting with vendor U-Boot.
>>>>>
>>>>> However, when booting using mainline U-Boot the ethernet PHY is never
>>>>> initialized or reset due to lack of a ethernet gmac driver for rk35xx.
>>>>
>>>> surely I'm using mainline u-boot.
>>
>> Ah, this might explain why I never experienced this issue: I am using
>> mainline barebox with GMAC support.
>>
>>>>> With an early work-in-progress gmac driver the ethernet PHY is working
>>>>> same as with vendor U-Boot, and the ethernet PHY is identified.
>>>>>
>>>>> This revert from using reset-gpios to using the deprecated
>>>>> snps,reset-gpio is probably the wrong way forward.
>>>>>
>>>>> I suspect there is a bug in net/phy/mdio_device.c on how reset-gpios
>>>>> is asserted/deasserted, it works differently than how I would expect it
>>>>> to work, and also differs in how U-Boot handles reset-gpios.
>>>>>
>>>>> Some earlier findings regarding this reset issue:
>>>>> https://github.com/Kwiboo/linux-rockchip/compare/rk3568-eth-phy-reset~2...rk3568-eth-phy-reset
>>>>>
>>>>> Will try to get a proper patch/rfc out later this weekend or early next
>>>>> week after re-testing that on latest kernel.
>>>>
>>>> thank you so much for your awesome work!
>>>
>>> Thanks, made some progress on tracking down the root cause.
>>> From what I have discovered so far there is a chicken-and-egg problem:
>>>
>>> - phy needs to be reset or phy_id read back as 0xffffffff on mdio bus
>>> - phy device is not created because a valid phy_id is not read back
>>> - phy device needs to be created before it can be reset
>>>
>>> Possible workarounds so far:
>>> - phy is reset in U-Boot
>>>   - very early work-in-progress at https://github.com/Kwiboo/u-boot-rockchip/commit/6ee80f9a895a32551cf30dd4252a4960ed80dfc9
>>> - phy is reset using mdio bus reset
>>>   - similar to old https://github.com/Kwiboo/linux-rockchip/commit/8597fcfa0c5c792dabb44a2db7b283c56c99ec6a
>>> - phy is reset using deprecated snps,reset-gpio
>>>   - similar to mdio bus reset
>>
>> There was a similar discussion here:
>> https://lore.kernel.org/all/CAMdYzYo_DGiO0UxJEb3xues7Um=X9AgPvz+Xp_YWb9pp9HaScg@mail.gmail.com/
>>
>> The approach that moves the reset to the MDIO bus has been mentioned
>> there as well. On the first glance this approach looks reasonable to me.
> 
> It does not look like U-Boot support mdio bus reset-gpios, so changing
> to that would require adding even more code into U-Boot to get ethernet
> working in U-Boot.
> 
> Moving to mdio bus would make it behave like with old snps,reset-gpio,
> however phy reset-gpios still describe the hw more accurately, a
> assert/deassert cycle of reset-gpios triggers a phy hard reset.
> 
> Do not know if it is possible to have both mdio bus reset and phy reset.
> 
> There also looks like there is a bug in dwmac-rk rk3568_set_to_rgmii,
> tx/rx delay is always enabled. It should be disabled in some phy modes.
> Can send a patch once I finish with the U-Boot ethernet driver.
> 
> Will try to complete a U-Boot driver that supports both phy reset-gpios
> and the deprecated snps,reset-gpio as a first step.

I have now created a small U-Boot dummy ethernet phy reset driver that
will assert/deassert reset-gpios to help make linux detect the PHY.

With this my ROCK 3 Model B detects the RTL8211F PHY again without any
changes to linux device tree.

See the U-Boot patch "HACK: net: Add dummy PHY reset-gpios driver"
at https://github.com/Kwiboo/u-boot-rockchip/commits/rk3568-2023.10-hacks

Will continue work on a fully working dwc_eth_qos_rockchip U-Boot driver,
currently having trouble getting TX working, at least RX is working.

Regards,
Jonas

> 
> Regards,
> Jonas
> 
>>
>> Best regards,
>> Michael
>>
>>> [...]