[Intel-gfx] [PATCH] drm/i915/lvds: don't restore hw state in the lid notifier for pch platforms

Daniel Vetter daniel.vetter at ffwll.ch
Mon Oct 14 19:14:54 CEST 2013

On Mon, Oct 14, 2013 at 6:52 PM, Roland Dreier <roland at kernel.org> wrote:
> On Wed, Oct 9, 2013 at 1:47 AM, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
>> It's a pain for two reasons:
>> - The vga plane redisablign requires actual legacy vgao i/o to pull
>>   of. The hw engineers really botched this one here :(
>> - There seem to be some BIOS out there which send out lid events when
>>   unplugging. Together with our broken DP code, which disables the
>>   port when the cable is lost, this results in an immediate modeset
>>   call, which can hang on the wait for outstanding flips.
> Unfortunately this still leads to a (different-looking) hang.  I
> captured the following dmesg after undocking my laptop and leaving it
> sitting there for a while.
> BTW, this seems to be a regression ... I used to be able to undock
> without this hang at least until 3.10 or so.

It's not a crash, and it's been there since forever - we've simply
added tons more self-consistency checks to the driver in 3.10 (and
extended those checks even more in recent kernels). At least the
current patch will duct-tape over the hang, fixing these DP woes for
real will take a bit longer ...
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch

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