Kernel 5.4 support

[autr]

Hello, I tested a 3.2 LCD with kernel 5.4 on Raspberry Pi OS, but isn't working yet - would be great to get this up and running as 5.4 adds libcamera and IMX477 support! Thank you

[FinlandApollo]

I'm eager to know as my 3.5" LCD with 5.4. kernel is just blank screen.

[autr]

Check the latest waveshare-dtoverlays;

https://github.com/swkim01/waveshare-dtoverlays

Where you can compile the latest device tree:

dtc -O dtb -o <output_filename>.dtb <input_filename>.dts

So for for 3.5" (version 3);

git clone https://github.com/swkim01/waveshare-dtoverlays
cd waveshare-dtoverlays
dtc -O dtb -o waveshare35c.dtb waveshare35c.dts
cp waveshare35c.dtb ../location/of/LCD-show/waveshare35c.dtb
# now follow LCD-show instructions...

It would make sense that this repo contains the dts as a submodule, and compiles the binary during the install script, but then, this repo is pretty sketchy.

[FinlandApollo]

Check the latest waveshare-dtoverlays;

https://github.com/swkim01/waveshare-dtoverlays

Where you can compile the latest device tree:

dtc -O dtb -o <output_filename>.dtb <input_filename>.dts

So for for 3.5" (version 3);

git clone https://github.com/swkim01/waveshare-dtoverlays
cd waveshare-dtoverlays
dtc -O dtb -o waveshare35c.dtb waveshare35c.dts
cp waveshare35c.dtb ../location/of/LCD-show/waveshare35c.dtb
# not follow LCD-show instructions...

It would make sense that this repo contains the dts as a submodule, and compiles the binary during the install script, but then, this repo is pretty sketchy.

Does this work with 35b-v2 if I just replace that waveshare35c.dtb and .dts files with those waveshare35b-v2.dts file?

The waveshare35a works but it makes colors inverted.

Also: "not follow LCD-show instructions". So am I just able to throw the dtb file to /boot/overlay -folder or how should I do this?

[autr]

Sorry, typo, meant to say: now follow LCD-show instructions

It might be better if I explain how I got there. While using a 3.2" V3 (ie. 32C) I found this commit and issue:

https://github.com/swkim01/waveshare-dtoverlays/commit/f0bdf7200c5822d73d2e013712c98903bfd96ca8 https://github.com/swkim01/waveshare-dtoverlays/issues/24

This is for 35A (ie. 3.5" V1), so I just replicated the change onto 32C dtoverlay:

https://github.com/swkim01/waveshare-dtoverlays/commit/0f2e3aca3e015c61a08229a0598eee717da73fa7

So for your LCD, you should either be able to use the 35A dtoverlay, or make the same change to 35B / C (and recompile).

[autr]

From what I can glean from the discussions here, the fbtft driver switched to using "gpio descriptors", so its an off-by-one error:

https://github.com/torvalds/linux/commit/c440eee1a7a1d0f2d5fc2ee6049e4a05da540f01 https://github.com/notro/fbtft/issues/546

[Zaryob]

I'm also living same issue. Whenever raspberrians publish 64bit OS without that support we wont be able to use it.

[Apteryks]

That's long been merged into this repo and the waveshare35b display (and others) work by simply adding dtoverlay=waveshare35b to your config.txt (tested using kernel8.img, the official 64-bit kernel used on raspbian bullseye 11). Could someone please close this?

[JimJ92120]

got it running on Pi 4B with kernel 6.1 on bullseye and bookworm (Raspberry PI OS 64-bit version) following [waveshare wiki instructions] (https://www.waveshare.com/wiki/3.5inch_RPi_LCD_(C)#Install_the_touch_driver)
(example for C version)

also assuming x-org is used (and not wayland on bookworm)

following must be run with root privilege:

./LCD35C-show

# now
sudo  ./LCD35C-show

then updating (or creating) /usr/share/X11/xorg.conf.d/99-fbdev.conf as mentioned here:
https://forums.raspberrypi.com/viewtopic.php?t=161512#p1048180

...
  # output to LCD screen
  Option "fbdev" "/dev/fb1"

  # or replace with this to output to HDMI instead
  Option "fbdev" "/dev/fb0"
...