OpenWrt/LEDE Project

  • Status Unconfirmed
  • Percent Complete
    0%
  • Task Type Bug Report
  • Category Base system
  • Assigned To No-one
  • Operating System All
  • Severity Low
  • Priority Very Low
  • Reported Version openwrt-19.07
  • Due in Version Undecided
  • Due Date Undecided
  • Private
Attached to Project: OpenWrt/LEDE Project
Opened by George - 05.07.2021

FS#3914 - Failsafe button is inverted under TP-Link TL-WR842N/ND v2

My 2 routers (TL-WR842v1, TL-WR842v2) were modded to have 64MB of RAM.
I also have TL-WR842v3 for reference.

This is great time to move from 17.01 to 19.07 (”refs/heads/openwrt-19.07” branch).
My build configuration is very simple: stock .config + Luci.
Config files are differ only on this line:

CONFIG_TARGET_ath79_generic_DEVICE_tplink_tl-wr842n-v1=y
CONFIG_TARGET_ath79_generic_DEVICE_tplink_tl-wr842n-v2=y
CONFIG_TARGET_ath79_generic_DEVICE_tplink_tl-wr842n-v3=y

Builds were made on ec76c365c1d60bf6a4f69b1ab3ce132f97f34dbb checkout (2021-06-14 - Koen Vandeputte - gitignore: add .ccache folder).

Boxes with hardware revisions v1 and v3 are working just fine.
But v2 almost always boots into failsafe mode :(
If I hold “wifi on/off” button v2 boots normal.
My wild guess: GPIO configuration is broken.

After ‘git bisect’ session I’ve found that following commit makes big difference:
2021-02-26 - Koen Vandeputte - kernel: bump 4.14 to 4.14.222 (b4a4d04b919b4a18a03e52a9e6bc18ddd924f554)
I’m not skilled enough to dig into kernel bisecting territory.

Before above commit router almost always boots normal.
After it router almost always boots into failsafe mode. But if I reboot it using reboot@SSH command it will boot just fine. So, power cycle ⇒ failsafe, reboot command ⇒ boots normal.

Looks like some sort of hardware initialization is made “too late” in boot process and querying GPIO state gives wrong readings.
That explains proper behavior after soft reboot.

George commented on 11.07.2021 17:56

Hardware revision of above device: "Ver: 2.0".
Now I have another box. Same problem. This one is "Ver: 2.1".

George commented on 11.07.2021 19:21

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