[Bug 38030] DPMS suspend fails to turn off monitor with my Radeon HD5750

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=38030

--- Comment #42 from Hans Nieser <hnsr at xs4all.nl> 2012-01-07 05:59:27 PST ---
Just wanted to chime in here as I'm having an identical issue with DPMS, the
exact sequence for me is:

  1) Invoke "sleep 5; xset dpms force off"
  2) Display goes fully black, with backlight off, 2-4 seconds pass
  3) Backlight turns on, OSD pops up and says "DVI", a second or so passes
  3) OSD says "No signal", a second or so passes
  4) Go to 2

One interesting thing is that I have two identical displays (2 x Iiyama ProLite
B2409HDS) where one is connected via DVI, the other is connected on the second
DVI port but using a DVI->VGA(D-SUB) adapter. However, the DPMS problem only
happens on the display connected on the DVI port, not the one that is connected
with an VGA cable. With both displays connected and enabled (mirror mode), the
VGA one turns off and stays off, the DVI one goes into the cycle described
above when DPMS 'off' activates.

Trying with only one display connected via either DVI or VGA does not change
anything; via DVI I get the DPMS cycle, via VGA it appears to work correctly.

Specs:

  Sapphire Radeon Vapor-X HD5850 1G GDDR5 Dual DVI-I/HDMI/DP
  libdrm from git master (adf1428915bfd0ee24758a3cbd56ce9b64f6eefb)
  xf86-video-ati from git master (eb6d769a087b2ed5952f477fc3f0b0625810a287)
  mesa from git master (1f125374e73d1718cd54c946826c76b09998c055)
  linux 3.1.6
  xorg-server 1.11.3
  gentoo

Turning off the display's 'Signal select: auto', explicitly setting it to
'DVI', doesn't seem to help in my case. I'll try the patch mentioned in
previous comments as well. Also, setting "drm_kms_helper.poll=0" on the kernel
commandline (something which chithead suggested on #radeon IRC) didn't help
either

I only installed this card today to replace an NVIDIA gpu that didn't perform
well under Gnome 3, so I'm not sure if this is some kind of regression. I do
remember having this problem before when I had this card installed in another
PC months ago, so I think this problem has been around for a while. I've not
had this problem with the nvidia GPU, and I might try fglrx later to see if it
happens there

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