beaglebone black hdmi micro-HDMI video output)

[Carl Trachte]

Sorry, forgot reply-all.  CBT

---------- Forwarded message ---------
From: Carl Trachte <ctrachte at gmail.com>
Date: Thu, Apr 9, 2020 at 7:36 PM
Subject: Re: beaglebone black hdmi micro-HDMI video output
To: Robert Crowston <crowston at protonmail.com>


Thank you.  You got me on track.  It does have to do with the boot process.

I should have mentioned I am using armv7 FreeBSD-12.1-RELEASE.  I
downloaded the install image for the SD card from here:

https://www.freebsd.org/where.html

on the BEAGLEBONE link.

The fix is not HDMI specific, but, rather, deals with the dts/dtb file:

"To get this functionality back users
+ should force usage of FreeBSD-specific DTB files by setting fdt_file
+ variable in /boot/loader.conf, i.e.:
+  fdt_file="beaglebone-black.dtb""

Essentially, you are telling the board to boot with the former FreeBSD
hardware list rather than the new one that is more generic.  The dtb
file has this information.  My understanding from googling and reading
is that the dts/dtb system saves having to develop a separate kernel
source tree for each arm board (not an expert).

This link has the necessary change:

https://reviews.freebsd.org/file/data/4bu7vx5qojflaztzjkcs/PHID-FILE-s2ct3tkxptikqfrh6f6p/D9432.diff''

More detail:

" ****************************** SPECIAL WARNING: ******************************

+20170205:
+ AM335x-based boards switched from using DTB files that contained
+ FreeBSD-specific layer to using unmodified upstream DTS. This
+ change was made to accommodate automatic board type detection by
+ U-Boot. Current upstream DTS files do not support spi1, i2c1,
+ pruss, and pmic devices. To get this functionality back users
+ should force usage of FreeBSD-specific DTB files by setting fdt_file
+ variable in /boot/loader.conf, i.e.:
+  fdt_file="beaglebone-black.dtb"
+ This change affects users of Beaglebone and Beaglebone Black boards.
+
 20170127:
  The WITH_LLD_AS_LD / WITHOUT_LLD_AS_LD build knobs have been renamed
  WITH_LLD_IS_LD / WITHOUT_LLD_IS_LD, for consistency with CLANG_IS_CC.
Index: sys/boot/fdt/dts/arm/beaglebone-black.dts
==================================================================="

Sorry to be so wordy, but I would like to be able to refer to this
later, assuming the requirement remains for a release or several.

Thanks again.

Carl Trache

On Thu, Apr 9, 2020 at 3:54 AM Robert Crowston <crowston at protonmail.com> wrote:
>
> AFAIK micro-HDMI is no different from regular HDMI, just a smaller connector.
>
> HDMI may work on the other Beagleboard models, but that could be due to a different chip rather than the connector.
>
> If there's no output at all, that sounds like a problem with the bootloader.
>
> Have you tried booting without the serial connection -- it may be the bootloader will only attach to one output. That's a pure guess though.
>
> Do you get any feedback on the serial port describing the display configuration in the bootloader?
>
> You could also try forcing freebsd to use the console as well as the serial port with the -D option, but I suspect if the bootloader didn't detect and configure video out, neither will the kernel.
>
>
> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
> On Wednesday, 8 April 2020 23:01, Carl Trachte <ctrachte at gmail.com> wrote:
>
> > Good afternoon. First e-mail to list.
> >
> > I have successfully installed FreeBSD on a Beaglebone Black. I am
> > currently connecting to it via a serial to usb connection with a
> > laptop (non-FreeBSD). This works very well.
> >
> > I have a micro-HDMI to HDMI cable, but I could not get any signal on
> > my monitor when I booted the Beaglebone. I have not tried this with a
> > Linux distro like the one that shipped originally with the Beaglebone
> > Black. Unfortunately I have overwritten that micro-SD card with
> > another operating system.
> >
> > Is the micro-HDMI to HDMI monitor supported on the Beaglebone Black?
> > I have googled but could not find an account of this working, although
> > HDMI is reported as being supported. I may have misunderstood the
> > scope and nature of the HDMI support.
> >
> > If the micro-HDMI cable approach is not supported, are there other
> > HDMI or VGA options for FreeBSD on the Beaglebone Black?
> >
> > Thanks so much for your help.
> >
> > Carl Trachte
> >
> > freebsd-arm at freebsd.org mailing list
> > https://lists.freebsd.org/mailman/listinfo/freebsd-arm
> > To unsubscribe, send any mail to "freebsd-arm-unsubscribe at freebsd.org"
>
>