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

Fri Feb 25 10:58:52 PST 2022

Hi Sander,

I don't have the GS1900-48 at hand or even my records. I am on vacation and I will only
be back in 10 days, we actually got stuck here in quarantine...
You can also test the GPIO access in U-Boot using md.l and mw.l using the the indirect
access register. I tested this once for the indirect table access registers and that
worked.
But I looked up when the GS1900-48 was released and it was around since at least 2013.
I would be surprised if there are _not_ different versions around. We know that there
_are_ actually different version with regards to the SoC. They use at least 3 different
processor generations including different work-arounds necessary. Have a look at the
forum on issues with reading non-existing PHYs and the port flooding table, which in SoC revisions
< D cannot be read and requires a shadow table (not implemented, since we always flood to
all ports, because port isolation overrides this anyway).
On the warning: At least the initial warning came from the lock debugging I compiled in,
which is based on Daniel's standard settings. IIRC, the lengthy warning was about
sleeping in the wrong context, maybe there was also something about an issue with lock
contention.

Cheers,
   Birger

On 24/02/2022 21:19, Sander Vanheule wrote:
> On Tue, 2022-02-22 at 23:39 +0100, Birger Koblitz wrote:
>> Hi,
>>
>> the information on the external GPIO resetting the board of
>> the Zyxel GS1900-48 comes from the hardware configuration
>> reported by the stock firmware. It says:
>> GS1900# show board
>> [...]
>> ====== Reset =================
>> Type: GPIO
>> GPIO: EXT_5
>> [...]
>> Using the rtk gpio commands in u-boot this can be confirmed.
> 
> Can you list the commands that you used to test this? My bootloader only supports "rtk
> network ..." and "cst pinSet ...".
> 
> 
>> On 22/02/2022 23:00, Sander Vanheule wrote:
>>> 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.
>>>
>>> [1] https://svanheule.net/switches/gs1900-48#board_details
>>> [2] https://svanheule.net/switches/gs1900-48#hard_reset_circuit
> 
> 
> Having another look at the source code of gpio-restart, the WARNING-s I reported in the
> patch's commit message occur at the following points of the GPIO output waveform:
> 
>       |< 100ms >|< 100 ms >|<   3000 ms   >|< Restart failed
> _____|_________|          |_______________|__ [ active ]
> _____X         \__________/                   [inactive]
>        |        |          |               |
>        |        |          |               ^ WARN @ drivers/power/reset/gpio-restart.c:46
>        |        |          |
>        |        |          ^ WARN @ drivers/gpio/gpiolib.c:3098
>        |        ^ WARN @ drivers/gpio/gpiolib.c:3098
>        |
>        ^ Restart should already occur here
> 
> 
> If everything is set up correctly, the system should restart before execution reaches the
> point where a warning can be emitted. If you say that you see a warning (any at all),
> AFAICT that means gpio-restart is not working.
> 
> As they say, the proof of the pudding is in the eating, so I soldered a jumper wire
> between the RTL8231's GPIO5 pin (U38:25) and the line driven by the hard reset button
> (U25:3) [https://svanheule.net/switches/gs1900-48#hard_reset_circuit].
> As expected from the analysis above, this results in a system rebooting without _any_
> warning (using an initramfs from yesterday's snapshot builds):
> 
> root at OpenWrt:/# reboot
> root at OpenWrt:/# [  185.092891] rtl83xx_fib_event: FIB_RULE ADD/DELL for IPv6 not supported
> [  185.101879] rtl83xx_fib_event: FIB_RULE ADD/DELL for IPv6 not supported
> [  185.111835] rtl83xx_fib_event: FIB_RULE ADD/DELL for IPv6 not supported
> [  185.120484] rtl83xx_fib4_del: found a route with id 1, nh-id 0
> [  185.127681] rtl83xx-switch switch at 1b000000: unknown nexthop, id 0
> [  185.149505] rtl83xx-switch switch at 1b000000: unknown nexthop, id 0
> [  185.157262] rtl83xx_fib4_del: found a route with id 2, nh-id 0
> [  185.164418] rtl83xx-switch switch at 1b000000: unknown nexthop, id 0
> [  185.173391] rtl83xx_fib4_del: no such gateway: 0.0.0.0
> [  185.225492] device lan01 left promiscuous mode
> [  185.230976] switch: port 1(lan01) entered disabled state
> ...
> [  187.735562] device lan50 left promiscuous mode
> [  187.741075] switch: port 50(lan50) entered disabled state
> [  187.794104] in rtl838x_eth_stop
> [  187.797945] rtl838x-eth 1b00a300.ethernet eth0: Link is Down
> [  188.329431] rtl83xx_fib_event: FIB_RULE ADD/DELL for IPv6 not supported
> [  188.337562] rtl83xx_fib_event: FIB_RULE ADD/DELL for IPv6 not supported
> [  188.345649] rtl83xx_fib_event: FIB_RULE ADD/DELL for IPv6 not supported
> [  188.353736] rtl83xx_fib_event: FIB_RULE ADD/DELL for IPv6 not supported
> [  188.543709] rtl83xx_fib4_del: no such gateway: 0.0.0.0
> [  188.549982] rtl83xx_fib4_del: no such gateway: 0.0.0.0
> [  188.559077] rtl83xx_fib_event: FIB_RULE ADD/DELL for IPv6 not supported
> [  188.567226] rtl83xx_fib_event: FIB_RULE ADD/DELL for IPv6 not supported
> [  188.576283] rtl83xx_fib4_del: no such gateway: 0.0.0.0
> [  188.582679] rtl83xx_fib4_del: no such gateway: 0.0.0.0
> [  192.871878] reboot: Restarting system
> 
> 
> U-Boot Version: 2.0.0.59413 (Jul 08 2015 - 10:01:28)
> 
> CPU:   750MHz
> DRAM:  128 MB
> FLASH: 16 MB
> Model: ZyXEL_GS1900_48
> SN:    S182L05000541
> 
> 
> Best,
> Sander
> 