amdisplay,
nxphdmi
—
Texas Instruments AM335x LCD display
driver
The
amdisplay driver supports the LCD controller
integrated in Texas Instruments' line of AM335x SoCs. The LCDC reads a
framebuffer from memory via DMA and scans it out at the proper frequency to
suit a display (along with the neccesary hsync/vsync/etc. signals) to a PHY
transmitter. The BeagleBone Black uses NXP/Freescale's TDA19988 HDMI
transmitter, which is additionally supported by the
nxphdmi driver.
intro(4),
wsdisplay(4),
wsfb(4)
The
amdisplay driver first appeared in
OpenBSD 6.2.
The
amdisplay driver was written by
Ian Sutton
<
ians@openbsd.org>. The
nxphdmi driver was written by
Oleksandr Tymoshenko
<
gonzo@freebsd.org>
and later ported to
OpenBSD.
On the BeagleBone Black, the LCDC and onboard eMMC NAND chip share the same set
of pads such that only one can be wired and used at a time. To boot from or
use the onboard storage, disable
amdisplay via
config(8)
in the kernel.
A display must be attached at boot time, otherwise
amdisplay will fail to configure.
Hotplugging is not supported.
Only 16-bit color depth is supported due to a silicon bug.