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

[Heiko Stuebner <heiko@sntech.de>]

Am Montag, 24. Juli 2023, 07:09:48 CEST schrieb FUKAUMI Naoki:
> hi,
> 
> On 7/24/23 07:54, Jonas Karlman wrote:
> > 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@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
> 
> your hack works fine on my ROCK 3A with mainline kernel.

very nice. Jonas, thanks for working on that.

So I'll disregard this dt patch.


Heiko



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