I’ve spent a couple of days on this and can’t say I’ve made any progress. I have a custom LCD cape modeled after the 4D-Systems LCD7. It has the same LCD connections, just doesn’t have the touchscreen, leds or buttons (and no Enable line either).
If I enable BB-BONE-LCD7-01:00A3 I get a single screen worth of data, sometimes just the mouse pointer, sometimes the touch screen calibration but regardless of what it is, it fades away to either black or to a half-white / half-black screen. I was encouraged by this and figured I just had to change the timings in the device tree to make it work.
I downloaded the latest overlays from git (bb.org-overlays) but what I’ve found is that if I simply copy BB-BONE-LCD7-01-00A3.dts to BB-BONE-LCD7-01-00A7.dts, change the version string in it from A3 to A7, rebuild, install and activate at boot (changing uEnv.txt) it won’t load.
The error in dmesg is: of_resolve: Could not find symbol ‘gpio0’. This in and of itself is no big deal because the entry in question is for the ‘Enter’ button which I don’t need. In fact I’ve removed the device tree entries for the touchscreen and the button GPIOs but that just shows other issues. Significantly, I get complaints that the ‘display-timings’ node is missing, which it is not.
The bottom line is that the device tree sources in git bb.org-overlays are obviously not the ones compiled into the 7.9 distribution or I’m missing something. The notes at https://github.com/beagleboard/bb.org-overlays only mention the 4.1 kernel. Is there another source or branch for the 3.8 kernel?. I’d prefer the 3.8 kernel because this is just one component of a project that includes using other hardware and a driver that I don’t yet have working on 4.1 but if I need to update to 4.1 then so be it.
I’m just looking for a little guidance before I spend even more time going down the wrong path.
– Mike Fallavollita