[PATCH] riscv: dts: spacemit: k3-pico-itx: Fix non-functional ethernet TX timing

[Yixun Lan]

Hi E Shattow,

On 00:29 Thu 11 Jun     , E Shattow wrote:
> Hi Andrew,
> 
> On 6/10/26 02:05, Andrew Rembrandt wrote:
> > On Wed, Jun 10, 2026 at 07:14:56 am Inochi Amaoto wrote:
> >> Do not do this, just leave the rx-internal-delay-ps untouched.
> > 
> > Sounds good, I'll leave v1 as-is. Many thanks for the review.
> > 
> > Regards,
> > 
> > Andrew
> > 
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv at lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
> 
> I do not notice any difference with or without this property present,
> tested Linux -next with U-Boot modification to devicetree:
> 
> load usb 0:1 $fdt_addr_r /dtb/spacemit/k3-pico-itx.dtb
> fdt addr $fdt_addr_r
> fdt resize
> fdt header get filesize totalsize
> fdt set /soc/ethernet at cac80000 tx-internal-delay-ps <400>
> load usb 0:1 $kernel_addr_r /EFI/BOOT/BOOTRISCV64.EFI
> # throwaway use of ping is workaround for broken vendor U-Boot
> ping 127.0.0.1; bootefi $kernel_addr_r $fdt_addr_r
> 
> Aside, there is still some problem with the driver which does cause it
> to fail. This can be reproduced by unloading the module and then loading
> the module; built from -next with 'olddefconfig' of debian Kconfig for
> kernel 7.1, no patches.
> 
> # modprobe -r dwmac_spacemit
> # modprobe dwmac_spacemit
> [   61.469745] spacemit-dwmac cac80000.ethernet end0: cannot attach to
> PHY (error: -ENODEV)
> 
> [   91.544646] spacemit-dwmac cac80000.ethernet end0: cannot attach to
> PHY (error: -ENODEV)
> 
The problem is unrelated to this patch itself, but I can actually confirm here

> If not reloading the module then I don't see any difference, traffic
> passes (ping 1.1.1.1) with or without your suggested
> tx-internal-delay-ps property. Is there a specific test to run to
> observe expected difference?
> 

Although I haven't narrowed down to the root cause, but it's kind of
something wrong with the reset procedure, remove it from phy node will fix
this issue..

+++ b/arch/riscv/boot/dts/spacemit/k3-pico-itx.dts
@@ -232,9 +232,6 @@ mdio {
                phy0: phy at 1 {
                        compatible = "ethernet-phy-ieee802.3-c22";
                        reg = <1>;
-                       reset-gpios = <&gpio 0 15 GPIO_ACTIVE_LOW>;
-                       reset-assert-us = <10000>;
-                       reset-deassert-us = <10000>;


-- 
Yixun Lan (dlan)