disable edid (hdmi, rgb video output)

[epi kao]

Hello all

where can i disable the edid from hdmi?
and where can i setup my own edid on the bbb?

(i have several small TFT's which has no edid-possibility)

@raspberry i can simply change a config.txt file for this.

thanks

[William Hermans]

I'm pretty sure( as I've seen it demonstrated a few times ) that there is a kernel config option to change the video output resolution. So here . . .

$ cat /boot/uEnv.txt |grep cmdline
#cmdline=coherent_pool=1M quiet cape_universal=enable
cmdline=ipv6.disable=1
#cmdline=coherent_pool=1M quiet cape_universal=enable video=HDMI-A-1:1024x768@60e
#cmdline=init=/opt/scripts/tools/eMMC/init-eMMC-flasher-v3.sh

I'm afraid I do not know much more than that however.

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[epi kao]

thanks, unfortunately with this i can only adjust the resolution and frame rate. In contrast with the possibility at raspberrys config.txt is this not really much.

So i think about v-porch, h-porch, de-mode, frequency etc...?
Is there a easy way to config this? Or how can make my own Edid directly on the bbb... (not with eeprom)

[William Hermans]

> thanks, unfortunately with this i can only adjust the resolution and frame rate. In contrast with the possibility at raspberrys > config.txt is this not really much.

No, "60e" I'm 99% sure has to do with refresh rate( frequency ). Frames per second has nothing to do with setting up a monitor . . .

 
> So i think about v-porch, h-porch, de-mode, frequency etc...?
> Is there a easy way to config this? Or how can make my own Edid directly on the bbb... (not with eeprom)

You could always download the support files for a known working / well respected LCD screen, and pour over the information . . .  Either that or do a google search for "linux how to edid config"

To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/f53e6ff4-04d3-40ef-a54e-c937a62dab55%40googlegroups.com.

[epi kao]

how you mean download? My several TFT's (7", 5" etc.) does not support EDID, so i must configure this directly in the bbb. But i really don't know where and how all this configuration can be done? With google i have found only manuals for the raspberry.
thanks

[William Hermans]

http://elinux.org/Beagleboard:BeagleBoneBlack_HDMI

A lot of information on that link, maybe something there can help you out.

On Sat, Jun 18, 2016 at 11:27 AM, epi kao <epi...@gmail.com> wrote:

how you mean download? My several TFT's (7", 5" etc.) does not support EDID, so i must configure this directly in the bbb. But i really don't know where and how all this configuration can be done? With google i have found only manuals for the raspberry.

thanks

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[epi kao]

thanks, and yes i already knew this link.
But there is only explained how to read (for debug) the EDID infos. That is not really usefull. I need more functions as only resolution and refresh rate....

So it seems that with a raspberry i have more adjust functions to set the hdmi output-timings?

[Charles Steinkuehler]

The video parameters you can adjust via the video= kernel command line
parameter are discussed in the kernel documentation:

https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/tree/Documentation/fb/modedb.txt?id=v3.8.13

If your LCD is connected via HDMI, that should be enough to get it
working. If you are directly connecting to the LCD via the RGB and
sync signals and you need more exact control over the video timings,
you should not use the HDMI driver. Instead, you'll want to disable
the HDMI driver and use the tilcd driver via a custom device-tree
overlay, like this example for a 7" 1024x600 panel with a resistive
touch-screen:

https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/BB-BONE-LCD7-01-00A1.dts#L230

...there are several other example LCD overlays in the same repository.

--
Charles Steinkuehler
cha...@steinkuehler.net

[Robert Nelson]

On Sat, Jun 18, 2016 at 5:18 PM, epi kao <epi...@gmail.com> wrote:
> thanks, and yes i already knew this link.
> But there is only explained how to read (for debug) the EDID infos. That is not really usefull. I need more functions as only resolution and refresh rate....
>
> So it seems that with a raspberry i have more adjust functions to set the hdmi output-timings?

Are you connecting thru the hdmi or thru the lcd 16bit/24bit interface?

The hdmi, you are limited to the what the nxp framer chip can handle.

For the lcd interface, you can specfy all those random settings..

https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/BB-BONE-LCD7-01-00A3.dts#L252-L285

Regards,

--
Robert Nelson
https://rcn-ee.com/

[epi kao]

Ok. thanks for this three links @charles and robert.. i will study this, hope it helps. It seems a little bit more difficult as with raspberry.

i should try both interface, because i have special size Tft with integrated hdmi to her rgb but also Tft's with only rgb interfaces. I also have the possibility to set a hdmi to rgb converter (tfp401a)...

[TJF]

Am Sonntag, 19. Juni 2016 00:18:00 UTC+2 schrieb epi kao:

thanks, and yes i already knew this link.
But there is only explained how to read (for debug) the EDID infos. That is not really usefull. I need more functions as only resolution and refresh rate....

So it seems that with a raspberry i have more adjust functions to set the hdmi output-timings?

Why do you think you have to provide this additional information? Let the frame buffer driver compute them. Therefor, as William mentioned, specify the cmdline variable in file /boot/uEnv.txt like

 

  cmdline=coherent_pool=1M quiet video=HDMI-A-1:800x480M@60e cape_universal=disable init=/lib/systemd/systemd

Note the "M" after the resolution here. It requires individual calculation of the timings (in contrast to reading them from a pre-defined table, see framebuffer documentation for details). That way you can skip EDID and specify any resolution in a convenient way. I guess RPi provides a similar feature, and you need not manually handle them using the config.txt file.

BR

[William Hermans]

I guess RPi provides a similar feature, and you need not manually handle them using the config.txt file.

The rPI BSP is a mess compared to the beaglebone. As far as I can tell there is nothing standard about it. However, it does make some things easier. Just as an example, here is some of the file structure, on my rPI3 Rasbian Jessie.

william@rpi:~$ lsblk
NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda           8:0    0 931.5G  0 disk
└─sda1        8:1    0 931.5G  0 part
mmcblk0     179:0    0  14.7G  0 disk
├─mmcblk0p1 179:1    0    60M  0 part /boot
└─mmcblk0p2 179:2    0  14.6G  0 part /

william@rpi:~$ ls /boot/
bcm2708-rpi-b.dtb       bcm2710-rpi-3-b.dtb  COPYING.linux  fixup_x.dat  LICENCE.broadcom  start_db.elf
bcm2708-rpi-b-plus.dtb  bootcode.bin         fixup_cd.dat   issue.txt    LICENSE.oracle    start.elf
bcm2708-rpi-cm.dtb      cmdline.txt          fixup.dat      kernel7.img  overlays          start_x.elf
bcm2709-rpi-2-b.dtb     config.txt           fixup_db.dat   kernel.img   start_cd.elf

william@rpi:~$ cat /boot/cmdline.txt
dwc_otg.lpm_enable=0 console=serial0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait

william@rpi:~$ cat /boot/config.txt
# For more options and information see
# http://www.raspberrypi.org/documentation/configuration/config-txt.md
# Some settings may impact device functionality. See link above for details

# uncomment if you get no picture on HDMI for a default "safe" mode
#hdmi_safe=1

# uncomment this if your display has a black border of unused pixels visible
# and your display can output without overscan
#disable_overscan=1

# uncomment the following to adjust overscan. Use positive numbers if console
# goes off screen, and negative if there is too much border
#overscan_left=16
#overscan_right=16
#overscan_top=16
#overscan_bottom=16

# uncomment to force a console size. By default it will be display's size minus
# overscan.
#framebuffer_width=1280
#framebuffer_height=720

# uncomment if hdmi display is not detected and composite is being output
#hdmi_force_hotplug=1

# uncomment to force a specific HDMI mode (this will force VGA)
#hdmi_group=1
#hdmi_mode=1

# uncomment to force a HDMI mode rather than DVI. This can make audio work in
# DMT (computer monitor) modes
#hdmi_drive=2

# uncomment to increase signal to HDMI, if you have interference, blanking, or
# no display
#config_hdmi_boost=4

# uncomment for composite PAL
#sdtv_mode=2

#uncomment to overclock the arm. 700 MHz is the default.
#arm_freq=800

# Uncomment some or all of these to enable the optional hardware interfaces
#dtparam=i2c_arm=on
#dtparam=i2s=on
#dtparam=spi=on

# Uncomment this to enable the lirc-rpi module
#dtoverlay=lirc-rpi

# Additional overlays and parameters are documented /boot/overlays/README

# Enable audio (loads snd_bcm2835)
dtparam=audio=on

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[epi kao]

Hello, thanks again.

so today i have try now with a HDMI TFT 1280x800 (EDID compatible) to force the Resolution to 800x480.

For this, i have try to edit the uEnv.txt file:

root@beaglebone:/media/root/rootfs/boot# vi uEnv.txt

then i have edit the cmdline as follow, but unfortunately the resolution does not change after restart, so whats wrong?:

uname_r=3.8.13-bone70

#dtb=

cmdline=coherent_pool=1M quiet video=HDMI-A-1:800x480M@60e cape_universal=disable init=/lib/systemd/systemd

##Example

then i have

[Charles Steinkuehler]

On 6/20/2016 8:36 AM, epi kao wrote:
> Hello, thanks again.
>
> so today i have try now with a HDMI TFT 1280x800 (EDID compatible) to force the
> Resolution to 800x480.
>
> For this, i have try to edit the uEnv.txt file:
> root@beaglebone:/media/root/rootfs/boot# vi uEnv.txt
>

> *then i have edit the cmdline as follow, but unfortunately the resolution does
> not change after restart, so whats wrong?:*

After the system boots, verify your kernel command line switches are
actually making it to the kernel by running:

cat /proc/cmdline

...and look through the output of dmesg for hints as to what might be
going wrong.

--
Charles Steinkuehler
cha...@steinkuehler.net

[epi kao]

so what i receive:

root@beaglebone:/# cat /proc/cmdline

console=tty0 console=ttyO0,115200n8 root=/dev/mmcblk0p1 rootfstype=ext4 rootwait fixrtc coherent_pool=1M quiet cape_universal=enable

BTW, i have read following code on a other side in the internet:

kms_force_mode=video=HDMI-A-1:800x480M@60

But unfortunately for me, it's not clear how to implement this correctly in the cmdline?

thanks

[Robert Nelson]

On Mon, Jun 20, 2016 at 9:00 AM, epi kao <epi...@gmail.com> wrote:
> so what i receive:
>
> root@beaglebone:/# cat /proc/cmdline
>
> console=tty0 console=ttyO0,115200n8 root=/dev/mmcblk0p1 rootfstype=ext4
> rootwait fixrtc coherent_pool=1M quiet cape_universal=enable
>
> BTW, i have read following code on a other side in the internet:
>
> kms_force_mode=video=HDMI-A-1:800x480M@60
>
>
> But unfortunately for me, it's not clear how to implement this correctly in
> the cmdline?

There's an example in /boot/uEnv.txt:

cmdline=coherent_pool=1M quiet video=HDMI-A-1:1024x768@60e

remove the "#" and set the video parameters you need.

[epi kao]

>remove the "#" and set the video parameters you need.

still not working...

[Charles Steinkuehler]

On 6/20/2016 9:25 AM, epi kao wrote:
> />remove the "#" and set the video parameters you need./
>
> still not working...

Provide your uEnv.txt, /etc/dogtag, and /proc/cmdline and we might be
able to make a suggestion for what to try next. Otherwise, we're just
guessing.

--
Charles Steinkuehler
cha...@steinkuehler.net

[Robert Nelson]

On Mon, Jun 20, 2016 at 9:25 AM, epi kao <epi...@gmail.com> wrote:
>>remove the "#" and set the video parameters you need.
>
> still not working...

okay, post your full, /boot/uEnv.txt

and what rootfs is this?

cat /etc/dogtag

[epi kao]

as requested (it seems that uEnv.txt has different directorys?, anyway I have changed uEnv.txt on the directory /media/root/rootfs/boot):

root@beaglebone:/# cat /etc/dogtag

BeagleBoard.org Debian Image 2016-01-24

root@beaglebone:/# cat /proc/cmdline

console=tty0 console=ttyO0,115200n8 root=/dev/mmcblk0p1 rootfstype=ext4 rootwait                      fixrtc coherent_pool=1M quiet cape_universal=enable

then the uEnv.txt file:

uname_r=3.8.13-bone70

dtb=

cmdline=coherent_pool=1M quiet video=HDMI-A-1:800x480M@60e cape_universal=disable init=/lib/systemd/systemd

##Example

#cape_disable=capemgr.disable_partno=

#cape_enable=capemgr.enable_partno=

##Disable HDMI/eMMC

#cape_disable=capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN,BB-BONE-EMMC-2G

##Disable HDMI

#cape_disable=capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN

##Disable eMMC

#cape_disable=capemgr.disable_partno=BB-BONE-EMMC-2G

##Audio Cape (needs HDMI Audio disabled)

#cape_disable=capemgr.disable_partno=BB-BONELT-HDMI

#cape_enable=capemgr.enable_partno=BB-BONE-AUDI-02

##enable BBB: eMMC Flasher:

##make sure, these tools are installed: dosfstools rsync

#cmdline=init=/opt/scripts/tools/eMMC/init-eMMC-flasher-v3.sh

uuid=682afa8f-f182-4b65-a144-91e06633914d

thanks

[Robert Nelson]

There's two uEnv.txt's for compatibility with old eMMC's..

/uEnv.txt -> /boot/uEnv.txt

HOWEVER, /uEnv.txt doesn't have the features of /boot/uEnv.txt

So make sure your uEnv.txt is found in /boot/uEnv.txt

Otherwise your /boot/uEnv.txt looks fine..

Regards

> --
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>
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[epi kao]

ok. now please find below the uEnv.txt directly from /boot (not from rootfs..)! but it don't  work although

#Docs: http://elinux.org/Beagleboard:U-boot_partitioning_layout_3.0

uname_r=4.1.15-ti-rt-r43

#uuid=

#dtb=

##BeagleBone Black/Green dtb's for v4.1.x (BeagleBone White just works..)

##BeagleBone Black: HDMI (Audio/Video) disabled:

#dtb=am335x-boneblack-emmc-overlay.dtb

##BeagleBone Black: eMMC disabled:

#dtb=am335x-boneblack-hdmi-overlay.dtb

##BeagleBone Black: HDMI Audio/eMMC disabled:

#dtb=am335x-boneblack-nhdmi-overlay.dtb

##BeagleBone Black: HDMI (Audio/Video)/eMMC disabled:

#dtb=am335x-boneblack-overlay.dtb

##BeagleBone Black: wl1835

#dtb=am335x-boneblack-wl1835mod.dtb

##BeagleBone Green: eMMC disabled

#dtb=am335x-bonegreen-overlay.dtb

cmdline=coherent_pool=1M quiet cape_universal=enable

#In the event of edid real failures, uncomment this next line:

cmdline=coherent_pool=1M quiet cape_universal=enable video=HDMI-A-1:x800@400e

##Example v3.8.x

#cape_disable=capemgr.disable_partno=

#cape_enable=capemgr.enable_partno=

##Example v4.1.x

#cape_disable=bone_capemgr.disable_partno=

#cape_enable=bone_capemgr.enable_partno=

##Disable HDMI/eMMC (v3.8.x)

#cape_disable=capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN,BB-BONE-EMMC-2G

##Disable HDMI (v3.8.x)

#cape_disable=capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN

##Disable eMMC (v3.8.x)

#cape_disable=capemgr.disable_partno=BB-BONE-EMMC-2G

##Audio Cape (needs HDMI Audio disabled) (v3.8.x)

#cape_disable=capemgr.disable_partno=BB-BONELT-HDMI

#cape_enable=capemgr.enable_partno=BB-BONE-AUDI-02

##enable Generic eMMC Flasher:

[Robert Nelson]

On Mon, Jun 20, 2016 at 9:57 AM, epi kao <epi...@gmail.com> wrote:
> ok. now please find below the uEnv.txt directly from /boot (not from
> rootfs..)! but it don't work although
>
> #Docs: http://elinux.org/Beagleboard:U-boot_partitioning_layout_3.0
>
> uname_r=4.1.15-ti-rt-r43
> #uuid=
> #dtb=
>
> ##BeagleBone Black/Green dtb's for v4.1.x (BeagleBone White just works..)
>
> ##BeagleBone Black: HDMI (Audio/Video) disabled:
> #dtb=am335x-boneblack-emmc-overlay.dtb
>
> ##BeagleBone Black: eMMC disabled:
> #dtb=am335x-boneblack-hdmi-overlay.dtb
>
> ##BeagleBone Black: HDMI Audio/eMMC disabled:
> #dtb=am335x-boneblack-nhdmi-overlay.dtb
>
> ##BeagleBone Black: HDMI (Audio/Video)/eMMC disabled:
> #dtb=am335x-boneblack-overlay.dtb
>
> ##BeagleBone Black: wl1835
> #dtb=am335x-boneblack-wl1835mod.dtb
>
> ##BeagleBone Green: eMMC disabled
> #dtb=am335x-bonegreen-overlay.dtb
>
> cmdline=coherent_pool=1M quiet cape_universal=enable
>
> #In the event of edid real failures, uncomment this next line:
> cmdline=coherent_pool=1M quiet cape_universal=enable
> video=HDMI-A-1:x800@400e

^ only have one "cmdline=" u-boot doesn't always pick the one you want
when you have two variables..

[epi kao]

ok. thank, it works :-)  failure was two command line, and the cmdline from the uEnv.txt at /boot was still wrong, below the correct:

#In the event of edid real failures, uncomment this next line:

cmdline=coherent_pool=1M quiet video=HDMI-A-1:800x480M@60e cape_universal=disable init=/lib/systemd/systemd

so now i am really interested if resolution like 1920x720 or 320x240 also works... maybe anyone still know this?

[Charles Steinkuehler]

On 6/20/2016 10:17 AM, epi kao wrote:
>
> so now i am really interested if resolution like 1920x720 or 320x240 also
> works... maybe anyone still know this?

You should be able to craft any resolution within the frequency range
of the AM335x LCD pixel clock. Very low resolutions (like 320x240)
may encounter problems since they require pixel doubling in the HDMI
framer to keep the HDMI clock within it's legal range. The driver
should handle this properly, but the code path is probably not tested
a bunch for HDMI (you'd typically connect a low-resolution LCD like
that directly rather than via HDMI).

Just try it and see.

--
Charles Steinkuehler
cha...@steinkuehler.net

[epi kao]

it seems that 320x240 is not working? what is the reason? it's to low? and how can i access now this resolution? thanks

[ramona...@gmail.com]

so because cmdline does not work with qvga i must study the variant with following link:

https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/BB-BONE-LCD7-01-00A1.dts#L230

does anyone know, if I can see also a result on the hdmi-output with that, or does I disable the hdmi-output with that?

thanks