unstable HDMI configuration

[PaulBraspi]

Hi,

I'm running Arch Linux 3.6.11-17-ARCH+ from the Noobs SD and the problem I'm having is that the HDMI monitor isn't consistently displaying at the config.txt-specified resolution/screen size from one [re-]boot to the next. Sometimes it's OK and sometimes it isn't. These changes are also reflected by /opt/vc/bin/tvservice -s

The config.txt-specified overscans are also sometimes being implemented and sometimes not. Sometimes there's a black bar margin, sometimes the shell text messages are right on the edge, and sometimes they run off the screen. Similarly at the top and bottom of the screen.

All of the above issues are seen in both console mode and lxde/startx

I'm using an offbrand hdmi monitor (Monita mt-9558t) with a 800x480 display. I can get /opt/vc/bin/tvservice -d edid.dat to write a file, but edidparser can't understand it (it reports a bad header: ff ff ff ff ff ff ff ff and exits with a -1). I'm sure the monitor doesn't help but it's all I've got and I figure there should be a way to force it to at least be consistent!

If anyone has any ideas, please advise! Thanks!


Here's my config.txt --

(comment lines removed for clarity)


overscan_left=-10
overscan_right=-10
overscan_top=-20
overscan_bottom=12

overscan_scale=1

hdmi_ignore_edid=0xa5000080
hdmi_ignore_cec=1

setfont=Lat2-Terminus16

hdmi_group=1

#mode=17 = 576i 50hz =21 for 576p 50hz
hdmi_mode=17

hdmi_drive=2

gpu_mem_512=316
gpu_mem_256=128
cma_lwm=16
cma_hwm=32
cma_offline_start=16

[EOF]


[edited for clarity and factual corrections]

[Phill Rymer]

how did you get arch to run mine wont

[PaulBraspi]

Hey Phill,

I'm not sure I can help you. I just selected Arch Linux on the Noobs SD and it installed and worked no problem.

All I can suggest is maybe you could try downloading the Arch ARM img from here -- http://www.raspberrypi.org/downloads -- and then followed this beginner's installation guide -- https://wiki.archlinux.org/index.php/Beginners%27_Guide

As for my original problem, apparently tvservice has an '-e' option that can be used to change the HDMI group and mode after boot up, so I'm going to try that... More details in this thread -- http://www.raspberrypi.org/phpBB3/viewt ... 29&t=24679

[edited to make corrections]

[PaulBraspi]

UPDATE --

Well, I couldn't get the custom hdmi-cvt settings documented in the above thread to work for me. The problem doesn't necessarily seem to be with the settings themselves, it's just that all attempts to subsequently reset the monitor with /opt/vc/bin/tvservice -e "CEA/DMT nn" failed -- ('[E] Failed to power on HDMI with explicit settings') -- except for "DMT 87", which did one of two things: 1. when executed from a script, it either failed or else cleared the screen and permanently killed the signal; and 2. when it was executed from config.txt, it *always* cleared the screen and killed the signal. In fact this is the first and only completely consistent monitor response I've ever had! (I'm not exaggerating.)

fbset -depth 8 && fbset -depth 16 -- didn't do anything to revive the monitor. (fwiw I'm not sure how this is supposed to work anyway; it switches the pixel depth but otherwise it doesn't seem to change anything).

On the plus side, I have a sort of sort of workaround, I guess -- If I force VGA output with CEA=1 and Mode=1, I get --

tvservice -s
state 0x12001a [HDMI CEA (1) RGB full 4:3 640x480 @60Hz progressive

fbset -s
mode "596x436"
geometry 596 436 596 436 16
timings 0 0 0 0 0 0 0
rgba 5/11,6/5,5/0,0/16
endmode

Weirdly, my monitor is 800x480 ie 5:3 not 4:3, and yet everything looks fine! there's no visible aspect ratio distortion either in the shell console text or in LXDE

Also, I'm getting these same values consistently! The only thing that changes is the overscan that's specified in config.txt; sometimes it works, and sometimes it gets ignored. fbset and tvservice still report the same values either way (which I think is what they're supposed to do)

So, as long as this keeps working, I have a workaround that I can live with.


On the other hand, I still don't understand why CEA=1 and MODE =1 is the only setting that works consistently, or why there's no aspect ratio distortion, and I also don't know if there's anything I can do to force the overscan settings to always work as specified, so if anyone has any ideas, please let me know! Thanks.

All config.txt settings below. Everything else is commented out --

overscan_left=-10
overscan_right=-10
overscan_top=-20

hdmi_ignore_edid=0xa5000080

setfont=Lat2-Terminus16

hdmi_group=1
hdmi_mode=1

gpu_mem_512=316
gpu_mem_256=128
cma_lwm=16
cma_hwm=32
cma_offline_start=16

[EOF]