Hi There,
My first post on this forum...
Idea there is to help others to onboard/migrate to LibreElec 11.0.3.
I have been a long time user of LibreElec (and used OpenElec before the fork).
And GeeXboX long before that for the older ones.
I thought i would share my experience and journey while upgrading from 9.2.8 to 11.0.3
First let me state that i have been a happy user on 9.2.8 since late 2020 : rock stable, not a single issue.
Back then, setup had been a 5 mns plug and play experience : burn your image file, start your rpi, enjoy...
Lately I got more and more 4k/hdr10 medias and I felt i was not getting the full experience for these medias on LibreElec 9.2.8.
4k medias were great but not really greater compared to 1080p.
hdr10 medias where a bit too dark, a bit to lavish.
So, based on my "plug and play" experience, i thought i would just burn the latest 11.0.3 and enjoy as before.
not quite 
First attempt up : no image.
Some quick googling, played with hdim_group and hdmi_mode : fail.
Some more googling, played with dtoverlay=vc4-fkms-v3d : fail (image ok but not cec).
Some extra googling, plugged/unplugged my hdmi wire during and/or after boot : fail (and a broken hdmi cable...).
At this stage (day 1), I decided to take a deep breath and attempted to deal with my frustration...
My original setup was : rpi4->avr (yamaha rx-v371)->tv (XR55X90J).
Maybe my avr, good but old, was the issue so i rewired it all to : rpi4 (with a new hdmi 2.0 cable)->tv->avr.
Second attempt : image ok in 4k desktop resolution.
I felt smart and victorious at this stage.
I did my quick config, rebooted and... back to original settings.
Confused, i did my config again and always the same issue.
Burned the image a few times onto a few different (hanging around) sd cards : same issue.
Again (day 2), took a deep breath and dealt with my impatience...
I quickly found out that the /storage partition was not resized !
Burned again the image several times on different sd cards (gparted), resized the partition: still no luck.
Ultimately lost for good one my 32gb sd cards in the process 
Finally bought a brand new one : and, at last, success!
Them come the evening where i could finally enjoy my 4k/hdr10 movie.
Except that it was slightly running behind and some scenes was laggy.
Still, 150 mns of Paul Atreides fighting the nasty Sardaukars and getting high on spice, all that on 4k/hdr10 was great
Again (day 3), breathed deeply and dealt with my eager to get it solved for good...
I was about to agressively overclock my rpi (and possibly cause some more troubles) when i read this page : https://wiki.libreelec.tv/configuration/4k-hdr .
I applied all recommendations and all of sudden, i was finally getting a super smooth experience.
120 minutes of Carol Danvers beating the Krees ass, all that on lag free 4k/hdr10, was super cool
My learning points :
-All answers are on this forum, carefully search, read it smartly and try with caution.
-Use the LibreElec wiki (rtfm guys).
-Use decent/new hardware (i replaced my power charger, my hdmi cable and my sd card).
-Be patient (by far not my first quality).
Bonus point :
Initially, sound from avr to tv was going thru hdmi, and sound from tv to avr (netflix tv app, disney tv app) was going thru an optic cable.
In the process of reviewing it all, i dropped the optic cable and went for an hdmi cable via the arc tv plug.
Sound is so much better : no need to play anymore with the remote to adjust sound during a movie, everything is perfectly balanced.
Not sure what is making the difference except may be that now this is the tv processing the sound?
So again, every experience is unique (i guess) : hopefully, this thread may help others...
Cheers to this community, open source, raspberry pi and linux and enjoy your movie evenings !
Regards,
Erwan
