[PATCH] realtek: ZyXEL GS1900-48: drop gpio-restart

Sander Vanheule sander at svanheule.net
Tue Feb 22 14:00:49 PST 2022

On Mon, 2022-02-21 at 21:23 +0100, Birger Koblitz wrote:
> Hi,
> > 
> > I just checked with my multimeter, and while the GPIO5 on the RTL8231 does go high/low
> > when I set the output high/low from Linux, my device certainly doesn't reset. The
> > other
> > GPIO lines on the chip do work, since SFP modules are correctly detected.
> > 
> > Birger, just to be sure, can you confirm that your device does reset with GPIO5 on the
> > RTL8231?
> Yes, it does.There is a warning, but then it reliably resets. That was why I left it
> in as is.

I had another hard look at my board, to check if something may be wrong physically, but I
cannot find anything. My device's board looks identical to the pictures on the switch wiki
[1], which I think you uploaded earlier.

There is some reset logic on the board [2], but I cannot figure out how GPIO5 would be
connected to it electrically. Unless I missed a via connecting to that pin on the RTL8231,
GPIO5 only appears to lead to TP2. GPIO5/TP2 does not appear to be connected electrically
to any part of the circuit next to SW1. I could add a bodge wire to connect TP2 to pad
U25:3, but gpio-restart should really work on unmodified hardware.

Does my description of the hard reset circuit on the wiki match your board?

FWIW, the GPIO description reported by the stock firmware on the XGS1250-12 claims that
internal GPIO21 can be used to reset the board, but you noted in the DTS it actually only
resets the phy-s. So it wouldn't be the first time the reported board config is partially


[1] https://svanheule.net/switches/gs1900-48#board_details
[2] https://svanheule.net/switches/gs1900-48#hard_reset_circuit

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