Captured communication between STC8 a d PoE board. Prococol looks really weird. The are two data lines, but no one can be interpolated as SCL for I2C communication. It have some data exchange every 2 sec.
Will attach collected sample tomorrow.
In case someone finds it useful, below is a firmware update for the RTL9303 based Hasivo F1100WP-4XS-4XGT. It contains an i2c-poe.ko kernel module that might be interesting to reverse engineer, for instance.
Do you really mean between STC8 and PoE board (with HS104PTI chips)?
or do you mean between Realtek SoC and STC8?
I donāt think weād care much about what communication occurs between STC8 and PoE board. Only what āour chipā (the Realtek SoC) needs to say to the STC8 to get the right PoE operations occuring.
What PoE chips are in use on this F1100WP-4XS-4XGT? We do already have the I2C Register Map for the HS104 chips, so thereās likely no benefit to reverse engineering that module if itās for the HS104 chips. Weād be better just writing our own driver against mainline linux PSE standards for it (which Iāve gotā¦ but untested currently).
Yeah. I mean exactly that. And you are right it is more important to captured communication between RTL and STC8.
Fwiw, I yolo installed the S1100W-8XGT-SE firmware on my S1100WP-8XGT-SE and PoE has been working fine for months without a proper driver.
I believe they use the same PoE board in all their switches. The specs are certainly the same from what I can tell. I just figured the kernel module might have some value in case their PoE board had some quirks or something that wasn't immediately obvious. 
It's also the first firmware update I've seen for this switch available in the wild, so I figured that might also make it interesting to some. 
Sorry if this is not for the right place to ask, but is it possible to flash S1100W-8XGT-SE into F1100W-4SX-4XGT? I think they shared the 9303 part, where 4 SFP+ is directed connected to 9303, and 4 RJ45 10G using RTL8264?
@bevanweiss Thx for your effort you put into this to make it work ...
I was wondering if you or some other folks have already a branch on git that has a commit with your latest tryouts?
I started to compile a image for S1100WP-8GT-SE ... with mdio and booted it via ymodem, which works. (rtk network on ...not) I was tinkering a little around with gpio and and different dts configs. But I am far away of bringing up an interface on any network speed.
best,
@bevanweiss ,Is that your latest tryout? https://github.com/bevanweiss/openwrt/commit/d195029a3e632b182e3f9b74d406f28bd8347c20
with that version the kernel detects no physical interfaces at all and no lan ports are shown up... hmm
Negative.
I just havenāt pushed to github lately.
Thereās still issues with the interfaces not actually passing traffic in my testing (at 1Gbps), which is likely because UBoot doesnāt correctly initialise them and OpenWRT doesnāt fully initialise them either (relying on the bootloader having mostly set them up).