[Intel-gfx] [PATCH] drm/i915/vlv: reset VLV media force wake request register

[Jani Nikula]

On Fri, 09 May 2014, Darren Hart <dvhart at linux.intel.com> wrote:
> On 5/9/14, 5:41, "Jani Nikula" <jani.nikula at intel.com> wrote:
>
>>Media force wake get hangs the machine when the system is booted without
>>displays attached. The assumption is that (at least some versions of)
>>the firmware has skipped some initialization in that case.
>>
>>Empirical evidence suggests we need to reset the media force wake
>>request register in addition to the render one to avoid hangs.
>>
>>Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=75895
>>Reported-by: Imre Deak <imre.deak at intel.com>
>>Reported-by: Darren Hart <dvhart at linux.intel.com>
>>Cc: stable at vger.kernel.org
>>Signed-off-by: Jani Nikula <jani.nikula at intel.com>
>
> Applied to 3.14.2 and tested on MinnowBoardMax A0 hardware (BayTrail-I,
> Atom E3825).
>
> * With no display connected, the boot no longer hangs and DRM prints
> sensible messages during boot:
> [    5.968837] [drm] GMBUS [i915 gmbus vga] timed out, falling back to bit
> banging on pin 2
> [    5.988037] i915 0000:00:02.0: No connectors reported connected with
> modes
> [    5.995744] [drm] Cannot find any crtc or sizes - going 1024x768
> [    6.004716] fbcon: inteldrmfb (fb0) is primary device
> [    6.013066] Console: switching to colour frame buffer device 128x48
> [    6.034147] i915 0000:00:02.0: fb0: inteldrmfb frame buffer device
> [    6.041168] i915 0000:00:02.0: registered panic notifier
> [    6.049820] ACPI: Video Device [GFX0] (multi-head: yes  rom: no  post:
> no)
> [    6.058788] acpi device:30: registered as cooling_device3
> [    6.065111] input: Video Bus as
> /devices/LNXSYSTM:00/device:00/PNP0A08:00/LNXVIDEO:00/input/input4
> [    6.075370] [drm] Initialized i915 1.6.0 20080730 for 0000:00:02.0 on
> minor 0
>
>
> * If a display is subsequently connected and X is restarted, it behaves as
> expected.
>
> * Booting with a display connected continue to work as expected.
>
> Tested-by: Darren Hart <dvhart at linux.intel.com>
>
> Thank you very much Jani!

Pushed to -fixes. Thanks for testing, Darren, and thanks for review,
Mika.

BR,
Jani.



>
> -- 
> Darren Hart					Open Source Technology Center
> darren.hart at intel.com				            Intel Corporation
>
>
>
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-- 
Jani Nikula, Intel Open Source Technology Center