18:17 <knuxify> ...anyways, i'm back to mainlining the Galaxy Tab 3 8.0 again, but am still stuck on the display. currently it just completely switches off when mainline boots (even with the backlight and panel drivers disabled...)

18:18 <knuxify> all of the gpio-related pinctrl seems fine, and all the init values for the backlight should be ok (not sure about the panel itself yet, but i'll figure it out eventually)

18:18 <knuxify> but i think if it was just a panel value configuration error, at least i'd see garbled output on the screen, not a blank screen with the backlight completely disabled...

18:19 <knuxify> (Viciouss - thanks for the hints you sent me via e-mail; unfortunately the display is connected via dsi, not fimd, so they weren't of much use... but at least it prompted me to clean up the pinctrl mess and try panel-simple instead of my own hacked-together panel driver :p)

18:21 <knuxify> there's some kind of resistor-capacitor-idk-i'm-not-an-electrical-engineeer on the board of the tablet that can be used as a test point - it connects to the 18v output on the lp8556 backlight chip, and *should* output 19.35v (like it does on downstream), but on mainline it outputs 14.35v instead

18:21 <knuxify> and trying to artificially boost it to 19v by changing the lp8556 config doesn't fix the issue

18:23 <knuxify> (...this is strange - 19-14=5v, and the only 5v thing in the service manual connected to the lp8556 chip is V_BATT which is an always-on 5v rail... probably just a coincidence)

18:23 <knuxify> not sure if i'm forgetting something, or tripping over some overvoltage protection by misconfiguring something, or if it's something related to the voltage regulator or charger ic... any ideas?

18:23 <knuxify> dtsi is https://github.com/knuxify/tab3-8.0-mainline/blob/d4dc9e9b6843a5ad3d2c3d3be853577cd38fb0f2/arch/arm/boot/dts/exynos4212-tab3.dtsi

18:24 <knuxify> i wish i could take more measurements from the other backlight chips, but sadly they're all under an rf shield and i don't have the tools to remove it :p

18:26 <knuxify> also, dmesg: https://gist.github.com/knuxify/308109eb2f653c88861be1bbd60d287f

18:28 <knuxify> ...to be fair, this might be more of a "linux-mainlining-general" question than a "linux-exynos" specific one... but it's worth a try :p