[REGRESSION] i915: No HDMI output with 4.4

[Daniel Vetter]

On Mon, Feb 08, 2016 at 12:17:07PM +0200, Oleksandr Natalenko wrote:
> Hi.
> 
> With Linux 4.4 external HDMI-attached monitor in not discovered by i915
> driver. Here is boot log related to drm and i915 for Linux 4.4/4.4.1 kernel:
> 
> ===
> kernel: [drm] Initialized drm 1.1.0 20060810
> kernel: [drm] Memory usable by graphics device = 2048M
> kernel: [drm] Replacing VGA console driver
> kernel: [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
> kernel: [drm] Driver supports precise vblank timestamp query.
> kernel: [drm] Initialized i915 1.6.0 20151010 for 0000:00:02.0 on minor 0
> kernel: i915 0000:00:02.0: No connectors reported connected with modes
> kernel: [drm] Cannot find any crtc or sizes - going 1024x768
> kernel: i915 0000:00:02.0: fb0: inteldrmfb frame buffer device
> ===
> 
> i915 is unable to find any connectors. Reattaching HDMI cable does not help.
> Note, we are talking about in-kernel i915 drm with no X involved (launching
> X does not change anything, though).
> 
> Linux 4.3 worked OK. Here is boot log for 4.3 kernel:
> 
> ===
> kernel: [drm] Initialized drm 1.1.0 20060810
> kernel: [drm] Memory usable by graphics device = 2048M
> kernel: [drm] Replacing VGA console driver
> kernel: [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
> kernel: [drm] Driver supports precise vblank timestamp query.
> kernel: [drm] Initialized i915 1.6.0 20150731 for 0000:00:02.0 on minor 0
> kernel: [drm:intel_set_pch_fifo_underrun_reporting [i915]] *ERROR* uncleared
> pch fifo underrun on pch transcoder A
> kernel: [drm:intel_pch_fifo_underrun_irq_handler [i915]] *ERROR* PCH
> transcoder A FIFO underrun
> kernel: i915 0000:00:02.0: fb0: inteldrmfb frame buffer device
> ===
> 
> Hardware:
> 
> ===
> [~]$ lscpu | grep "Model name"
> Model name:            Intel(R) Pentium(R) CPU G2020 @ 2.90GHz
> 
> [~]$ lspci | grep VGA
> 00:02.0 VGA compatible controller: Intel Corporation Xeon E3-1200 v2/3rd Gen
> Core processor Graphics Controller (rev 09)
> ===
> 
> and xrandr output (with 4.3 kernel):
> 
> ===
> [~]$ xrandr --listproviders
> Providers: number : 1
> Provider 0: id: 0x47 cap: 0xb, Source Output, Sink Output, Sink Offload
> crtcs: 4 outputs: 4 associated providers: 0 name:Intel
> 
> [~]$ xrandr
> Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
> DP1 disconnected (normal left inverted right x axis y axis)
> HDMI1 connected primary 1920x1080+0+0 (normal left inverted right x axis y
> axis) 510mm x 290mm
>    1920x1080     60.00*+  50.00    59.94
>    1920x1080i    60.00    50.00    59.94
>    1680x1050     59.88
>    1400x1050     59.95
>    1600x900      60.00
>    1280x1024     60.02
>    1440x900      59.90
>    1280x800      59.91
>    1152x864      59.97
>    1280x720      60.00    50.00    59.94
>    1024x768      60.00
>    800x600       60.32
>    720x576       50.00
>    720x480       60.00    59.94
>    640x480       60.00    59.94
> VGA1 disconnected (normal left inverted right x axis y axis)
> VIRTUAL1 disconnected (normal left inverted right x axis y axis)
> ===
> 
> Ideas?

Can you please retest with latest -rc? There's been some bugs in the HDMI
detection changes, which should be fixed now.

If that doesn't help please try to bisect which exact change caused the
regression.

Thanks, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch