[PATCH v2] drm/i915: gen4: work around hang during hibernation

[Bjørn Mork]

Jani Nikula <jani.nikula at intel.com> writes:

> On Mon, 02 Mar 2015, Imre Deak <imre.deak at intel.com> wrote:
>> Bjørn reported that his machine hang during hibernation and eventually
>> bisected the problem to the following commit:
>>
>> commit da2bc1b9db3351addd293e5b82757efe1f77ed1d
>> Author: Imre Deak <imre.deak at intel.com>
>> Date:   Thu Oct 23 19:23:26 2014 +0300
>>
>>     drm/i915: add poweroff_late handler
>>
>> The problem seems to be that after the kernel puts the device into D3
>> the BIOS still tries to access it, or otherwise assumes that it's in D0.
>> This is clearly bogus, since ACPI mandates that devices are put into D3
>> by the OSPM if they are not wake-up sources. In the future we want to
>> unify more of the driver's runtime and system suspend paths, for example
>> by skipping all the system suspend/hibernation hooks if the device is
>> runtime suspended already. Accordingly for all other platforms the goal
>> is still to properly power down the device during hibernation.
>>
>> v2:
>> - Another GEN4 Lenovo laptop had the same issue, while platforms from
>>   other vendors (including mobile and desktop, GEN4 and non-GEN4) seem
>>   to work fine. Based on this apply the workaround on all GEN4 Lenovo
>>   platforms.
>> - add code comment about failing platforms (Ville)
>>
>> Reference: http://lists.freedesktop.org/archives/intel-gfx/2015-February/060633.html
>> Reported-and-bisected-by: Bjørn Mork <bjorn at mork.no>
>> Signed-off-by: Imre Deak <imre.deak at intel.com>
>
> Bjørn, I would really appreciate your Tested-by on this patch before I
> queue it for v4.0 and cc: stable for v3.19.

No problem. This version still works fine for me.  Feel free to add

Tested-by: Bjørn Mork <bjorn at mork.no>



Bjørn