[Bug 2859] Flickering or blanking on DVI output of Radeon 9200/9250

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https://bugs.freedesktop.org/show_bug.cgi?id=2859          
     




------- Additional Comments From sroland at tungstengraphics.com  2007-01-18 05:27 -------
Created an attachment (id=8437)
 --> (https://bugs.freedesktop.org/attachment.cgi?id=8437&action=view)
print out the tmds table

(In reply to comment #70)
> Sorry to reply to myself in response to comment #67 (my last post):
> 
> In git-commit 2b0cdd9448a24ea067b0d78f319b99c1041df2e0 of module
> xf86-video-ati a change was committed which enabled the retrieving
> the tmds-pll-config-values from the BIOS. The same commit also changed
> the default tmds-pll-init-values.
> 
> When disabling the BIOS-sequence, our blanking problem disappeared
> (mostly) and we got the former (better) behaviour back. So it seems,
> getting the info from the BIOS is not fully reliable (at least for our
> cards). I left the changed default tmds-pll-init-values as defined in
> the commit mentioned above.
> 
> I am more than willing to help in debugging this problem (we have
> a rather big "testbed") but need some hints what the tmds-init-values
> mean and how the BIOS sequence is expected to work.
Could you print out the table (the values as retrieved from the bios) using the
attached patch?
Basically, the tmds init values are "magic numbers" used to program the tmds
pll, it seems different values are optimal for different pixel clocks.
Actually, I had a problem with those values too, though the bios-supplied ones
and the default ones were identical for me, but the monitor would switch off in
a very short time if some 3d activity was on. Turns out it works just well if I
used the values intended for a very slightly higher pixel clock (155Mhz and
higher, whereas the actual pixel clock was 154Mhz). In any case, fglrx had the
same problem. I suspect the values need to differ depending on the external
components of a card, if someone wouldn't use reference layout, but that's just
a guess.          
     
     
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