[Intel-gfx] [PATCH v5 1/4] drm/i915: Fix modeset handling during gpu reset, v5.

[Maarten Lankhorst]

Op 08-08-16 om 10:05 schreef Ville Syrjälä:
> On Mon, Aug 08, 2016 at 09:52:49AM +0200, Maarten Lankhorst wrote:
>> Hey,
>>
>> Op 05-08-16 om 22:28 schreef ville.syrjala at linux.intel.com:
>>> From: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>>>
>>> This function would call drm_modeset_lock_all, while the suspend/resume
>>> functions already have their own locking. Fix this by factoring out
>>> __intel_display_resume, and calling the atomic helpers for duplicating
>>> atomic state and disabling all crtc's during suspend.
>>>
>>> Changes since v1:
>>> - Deal with -EDEADLK right after lock_all and clean up calls
>>>   to hw readout.
>>> - Always take all modeset locks so updates during gpu reset are blocked.
>>> Changes since v2:
>>> - Fix deadlock in intel_update_primary_planes.
>>> - Move WARN_ON(EDEADLK) to __intel_display_resume.
>>> - pctx -> ctx
>>> - only call __intel_display_resume on success in intel_display_resume.
>>> Changes since v3:
>>> - Rebase on top of dev_priv -> dev change.
>>> - Use drm_modeset_lock_all_ctx instead of drm_modeset_lock_all.
>>> Changes since v4 [by vsyrjala]:
>>> - Deal with skip_intermediate_wm
>>> - Update comment w.r.t. mode_config.mutex vs. ->detect()
>>> - Rebase due to INTEL_GEN() etc.
>> Setting skip_intermediate_wm seems to have already been upstreamed and I missed it, but
>> this may blow up in .crtc_enable, which programs in the intermediate wm's which is used
>> until all planes are enabled.
> What blows up and how?
>
> Even if it can blow up we don't have any two stage wm stuff for pre-g4x at
> this time anyway, so -ENOCARE at this point really.
>
>> I fear this may blow up in interesting ways. And it should probably be using
>> dev_priv->wm.distrust_bios_wm instead like on SKL.
> Sigh. How many ways do we need to do the same thing?
>
> Anywyas, what we should really do is sanitize the current wms better
> at readout time, and then we shouldn't need these flags at all.
>
Yeah, slightly different approach of accomplishing the same. :-/

distrust_bios_wm pulls in the whole state and recalculates it, while sanitize_watermarks runs at the end of initial config.
Maybe get_hw_state for ILK should set the flag too, and  then stuff final wm in intermediate. And then kill off the skip_intermediate_wm flag.

~Maarten