LCD Shield with upstream kernel?

[fvolk]

I currently run the LCD shield with an old Odroid image on a C2.

Almost all of my other C2s and C4s run 5.7.7 currently, so thinking of an upgrade,
before I try it myself, maybe someone can comment whether an upgrade to
a C2 or even C4 with a current kernel will work?

Or alternatively, what patches/how many patches I have to apply to get a text console with framebuffer for a status display, X support is not needed.

Thank you for an estimate

[odroid]

I don't think upstream kernel support the 3.5inch LCD shield.
You might need to port the flexfb driver with hktft35 configuration.
https://wiki.odroid.com/accessory/displ ... uch_driver

[fvolk]

There's now a bunch of "tiny lcd" drivers in 5.8 - does this help in any way?

linux58.png (56.47 KiB) Viewed 2133 times

[mad_ady]

My c2 with 3.5" is still on 18.04. Haven't had the courage to try to upgrade it yet. Would love to see it supported on mainline

[brad]

I'm going to try viewtopic.php?p=309332#p309332 and report back

[brad]

I have taken a good look at the LCD schematics and the proposed kernel driver for the display ili9488 https://patchwork.kernel.org/project/dr ... gmail.com/

As the driver is for 4 wire spi but I think the 3.5" shield is hardwired for MIPI DBI only we will need a different driver or add MIPI DBI support to the linked patch above. I was hoping to be able to communicate to the Shield via SPI but it appears this is not possible unless some of the unused pins on the shield link to the ili9488 spi interface pins.

When I have some more time will see if I can try to port hardkernel driver to mainline for MIPI-DBI interface integration.

[fvolk]

When I have some more time will see if I can try to port hardkernel driver to mainline for MIPI-DBI interface integration.

ping? :-)

[odroid]

fbtft/flexfb stuff were removed since Kernel 5.4 introduced.
https://github.com/notro/fbtft/wiki#fbt ... gone-in-54

Therefore, this tiny-DRM project seems to be worth to try.
If it can be adopted to @tobetter's upstream kernel 5.10 branch for C4/N2, we can probably use the Panfrost GPU drivers on the 3.5inch DBI and 3.2inch SPI LCD display.
https://github.com/notro/tinydrm

[rooted]

That would be awesome.

[fvolk]

If it can be adopted to @tobetter's upstream kernel 5.10 branch for C4/N2

tobetter's 5.10 kernel also boots/works on C2, so there is hope.... :-)

[tobetter]

The latest kernel (5.10.16) from my Github branch is able to support 3.2" / 3.5" LCD shield from Hardkernel. In order to enable them respectively, device tree overlay trick must be supported by editing /boot/config.ini and this file will be generated once latest package odroid-base is installed.

Code: Select all

$ sudo apt update
$ sudo apt intall odroid-base
$ ls /boot/config.ini

From the default /boot/config.ini, change the line 3 with hktft35 for 3.5" LCD Shield or hktft32 for 3.2" LCD Shield. This change will make new framebuffer device on the next boot.

Code: Select all

  1 [generic]
  2 overlay_resize=16384
  3 overlay_profile="hktft35"
  4 overlays="spi0 i2c0 i2c1"
  5 
  6 [overlay_custom]
  7 overlays="i2c0 i2c1"
  8 
  9 [overlay_hktft32]
 10 overlays="hktft32"
 11 
 12 [overlay_hktft35]
 13 overlays="hktft35 sx865x-i2c1"

Currently, ARM Mali Bifrost can play on the LCD screen but Panfrost cannot. Not figure yet why.

[odroid]

The framerate seems to be 10fps or something like that.
But, I'm very happy to see the nice OpenGL-ES2 3D rendering show on the small display.

[brad]

To celebrate this great news with C4 users, we are selling the LCD shield at $8 only.
https://www.hardkernel.com/shop/3-5inch ... en-shield/

[mad_ady]

Tempting!

[rooted]

Tempting!

You already have one don't you?

[mad_ady]

Yes. And pleased with it! Though I prefer it to the vu7 for its case availability. That's why it's a pity the case doesn't fit the c4

[rooted]

Yes. And pleased with it! Though I prefer it to the vu7 for its case availability. That's why it's a pity the case doesn't fit the c4

Perhaps @hominoid may add one to his already excellent OpenSCAD library of cases.