Black screen with nouveau in 3.8.x (regression)

[Nick Bowler <nbowler@elliptictech.com>]

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Hi folks,

Yesterday I upgraded one of my machines to 3.8.2 from 3.6.6.  This
machine has an old NV36 AGP board.  With the new kernel, as soon as
nouveau takes over the console the display connected via DVI goes dark
(the monitor goes into standby mode).  The display connected via VGA
continues to work fine.

Starting Xorg does not correct the problem.  Nouveau seems to know
that the display is connected:

  % cat /sys/class/drm/card0-DVI-I-1/status
  connected

I don't see anything unusual in the log either (full log attached):

  % dmesg -t | grep -iE 'drm|nouveau'
  [drm] Initialized drm 1.1.0 20060810
  nouveau  [  DEVICE][0000:01:00.0] BOOT0  : 0x436200a1
  nouveau  [  DEVICE][0000:01:00.0] Chipset: NV36 (NV36)
  nouveau  [  DEVICE][0000:01:00.0] Family : NV30
  nouveau  [   VBIOS][0000:01:00.0] checking PRAMIN for image...
  nouveau  [   VBIOS][0000:01:00.0] ... appears to be valid
  nouveau  [   VBIOS][0000:01:00.0] using image from PRAMIN
  nouveau  [   VBIOS][0000:01:00.0] BMP version 5.28
  nouveau  [   VBIOS][0000:01:00.0] version 04.36.20.21
  nouveau W[  PTIMER][0000:01:00.0] unknown input clock freq
  nouveau  [     PFB][0000:01:00.0] RAM type: DDR1
  nouveau  [     PFB][0000:01:00.0] RAM size: 256 MiB
  nouveau 0000:01:00.0: putting AGP V3 device into 8x mode
  nouveau  [     DRM] VRAM: 255 MiB
  nouveau  [     DRM] GART: 64 MiB
  nouveau  [     DRM] BMP BIOS found
  nouveau  [     DRM] BMP version 5.40
  nouveau  [     DRM] Bios version 04.36.20.21
  nouveau  [     DRM] DCB version 2.2
  nouveau  [     DRM] DCB outp 00: 01000300 00009c40
  nouveau  [     DRM] DCB outp 01: 02010310 00009c40
  nouveau  [     DRM] DCB outp 02: 04000302 00000000
  nouveau  [     DRM] DCB outp 03: 02020321 00000303
  nouveau  [     DRM] Loading NV17 power sequencing microcode
  nouveau  [     DRM] Saving VGA fonts
  [drm] Supports vblank timestamp caching Rev 1 (10.10.2010).
  [drm] No driver support for vblank timestamp query.
  nouveau  [     DRM] 0xE51A: Parsing digital output script table
  nouveau  [     DRM] 0 available performance level(s)
  nouveau  [     DRM] c: core 425MHz memory 501MHz voltage 1350mV
  nouveau  [     DRM] MM: using M2MF for buffer copies
  nouveau  [     DRM] Setting dpms mode 3 on vga encoder (output 0)
  nouveau  [     DRM] Setting dpms mode 3 on vga encoder (output 1)
  nouveau  [     DRM] Setting dpms mode 3 on tmds encoder (output 2)
  nouveau  [     DRM] Setting dpms mode 3 on TV encoder (output 3)
  nouveau  [     DRM] allocated 1280x1024 fb: 0x9000, bo ffff88007b6ae000
  fbcon: nouveaufb (fb0) is primary device
  nouveau  [     DRM] 0xE51A: Parsing digital output script table
  nouveau  [     DRM] Setting dpms mode 0 on tmds encoder (output 2)
  nouveau  [     DRM] Output DVI-I-1 is running on CRTC 0 using output C
  nouveau  [     DRM] Setting dpms mode 0 on vga encoder (output 1)
  nouveau  [     DRM] Output VGA-1 is running on CRTC 1 using output B
  fb0: nouveaufb frame buffer device
  drm: registered panic notifier
  [drm] Initialized nouveau 1.1.0 20120801 for 0000:01:00.0 on minor 0

I started a bisection... here's the first steps so far.  I will try to
finish the procedure over the next couple days but I'm reporting this
now in case someone needs me to get some other info.

  git bisect start 'drivers/gpu/drm'
  # good: [3820288942d1c1524c3ee85cbf503fee1533cfc3] Linux 3.6.6
  git bisect good 3820288942d1c1524c3ee85cbf503fee1533cfc3
  # bad: [19b00d2dc9bedf0856e366cb7b9c7733ded659e4] Linux 3.8.2
  git bisect bad 19b00d2dc9bedf0856e366cb7b9c7733ded659e4
  # good: [a0d271cbfed1dd50278c6b06bead3d00ba0a88f9] Linux 3.6
  git bisect good a0d271cbfed1dd50278c6b06bead3d00ba0a88f9
  # bad: [daed2dbb7ea4d179e472396ce46377fe758d5faf] drm/i915: use the CPU and PCH transcoders on lpt_pch_enable
  git bisect bad daed2dbb7ea4d179e472396ce46377fe758d5faf
  # good: [df86b5765a48d5f557489577652bd6df145b0e1b] drm/savage: re-add busmaster enable, regression fix
  git bisect good df86b5765a48d5f557489577652bd6df145b0e1b
  # bad: [39df01cd6ce9f6dd755ace0030e2bebe75da7727] Merge branch 'drm-fixes-3.7' of git://people.freedesktop.org/~agd5f/linux into drm-fixes
  git bisect bad 39df01cd6ce9f6dd755ace0030e2bebe75da7727

Thanks,
-- 
Nick Bowler, Elliptic Technologies (http://www.elliptictech.com/)

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