Re: [PATCH 2/7] drm/i915/gen11: Link nv12 Y and UV planes in the atomic state, v3.

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Op 24-09-18 om 15:18 schreef Ville Syrjälä:
> On Mon, Sep 24, 2018 at 02:35:13PM +0200, Maarten Lankhorst wrote:
>> Op 21-09-18 om 21:31 schreef Ville Syrjälä:
>>> On Fri, Sep 21, 2018 at 09:35:52PM +0300, Ville Syrjälä wrote:
>>>> On Fri, Sep 21, 2018 at 07:39:40PM +0200, Maarten Lankhorst wrote:
>>>>> To make NV12 working on icl, we need to update 2 planes simultaneously.
>>>>> I've chosen to do this in the CRTC step after plane validation is done,
>>>>> so we know what planes are (in)visible. The linked Y plane will get
>>>>> updated in intel_plane_update_planes_on_crtc(), by the call to
>>>>> update_slave, which gets the master's plane_state as argument.
>>>>>
>>>>> The link requires both planes for atomic_update to work,
>>>>> so make sure skl_ddb_add_affected_planes() adds both states.
>>>>>
>>>>> Changes since v1:
>>>>> - Introduce icl_is_nv12_y_plane(), instead of hardcoding sprite numbers.
>>>>> - Put all the state updating login in intel_plane_atomic_check_with_state().
>>>>> - Clean up changes in intel_plane_atomic_check().
>>>>> Changes since v2:
>>>>> - Fix intel_atomic_get_old_plane_state() to actually return old state.
>>>>> - Move visibility changes to preparation patch.
>>>>> - Only try to find a Y plane on gen11, earlier platforms only require a single plane.
>>>>>
>>>>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
>>>>>
>>>>> fixup Y/UV Linkage
>>>>>
>>>>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
>>>>> ---
>>>>>  drivers/gpu/drm/i915/intel_atomic_plane.c | 106 ++++++++++++++++++----
>>>>>  drivers/gpu/drm/i915/intel_display.c      |  57 ++++++++++++
>>>>>  drivers/gpu/drm/i915/intel_drv.h          |  53 +++++++++++
>>>>>  drivers/gpu/drm/i915/intel_pm.c           |  12 ++-
>>>>>  4 files changed, 210 insertions(+), 18 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/i915/intel_atomic_plane.c b/drivers/gpu/drm/i915/intel_atomic_plane.c
>>>>> index 984bc1f26625..522699085a59 100644
>>>>> --- a/drivers/gpu/drm/i915/intel_atomic_plane.c
>>>>> +++ b/drivers/gpu/drm/i915/intel_atomic_plane.c
>>>>> @@ -121,7 +121,11 @@ int intel_plane_atomic_check_with_state(const struct intel_crtc_state *old_crtc_
>>>>>  	crtc_state->nv12_planes &= ~BIT(intel_plane->id);
>>>>>  	intel_state->base.visible = false;
>>>>>  
>>>>> -	/* If this is a cursor plane, no further checks are needed. */
>>>>> +	/* Destroy the link */
>>>>> +	intel_state->linked_plane = NULL;
>>>>> +	intel_state->slave = false;
>>>>> +
>>>>> +	/* If this is a cursor or Y plane, no further checks are needed. */
>>>>>  	if (!intel_state->base.crtc && !old_plane_state->base.crtc)
>>>>>  		return 0;
>>>>>  
>>>>> @@ -142,27 +146,76 @@ int intel_plane_atomic_check_with_state(const struct intel_crtc_state *old_crtc_
>>>>>  					       state);
>>>>>  }
>>>>>  
>>>>> -static int intel_plane_atomic_check(struct drm_plane *plane,
>>>>> -				    struct drm_plane_state *new_plane_state)
>>>>> +static int intel_plane_atomic_check(struct drm_plane *drm_plane,
>>>>> +				    struct drm_plane_state *new_drm_plane_state)
>>>>>  {
>>>>> -	struct drm_atomic_state *state = new_plane_state->state;
>>>>> -	const struct drm_plane_state *old_plane_state =
>>>>> -		drm_atomic_get_old_plane_state(state, plane);
>>>>> -	struct drm_crtc *crtc = new_plane_state->crtc ?: old_plane_state->crtc;
>>>>> -	const struct drm_crtc_state *old_crtc_state;
>>>>> -	struct drm_crtc_state *new_crtc_state;
>>>>> -
>>>>> -	new_plane_state->visible = false;
>>>>> +	struct intel_atomic_state *state =
>>>>> +		to_intel_atomic_state(new_drm_plane_state->state);
>>>>> +	struct intel_plane *plane = to_intel_plane(drm_plane);
>>>>> +	const struct intel_plane_state *old_plane_state =
>>>>> +		intel_atomic_get_old_plane_state(state, plane);
>>>>> +	struct intel_plane_state *new_plane_state =
>>>>> +		to_intel_plane_state(new_drm_plane_state);
>>>>> +	struct intel_crtc *crtc = to_intel_crtc(
>>>>> +		new_plane_state->base.crtc ?:
>>>>> +		old_plane_state->base.crtc);
>>>>> +	const struct intel_crtc_state *old_crtc_state;
>>>>> +	struct intel_crtc_state *new_crtc_state;
>>>>> +	struct intel_plane *linked = old_plane_state->linked_plane;
>>>>> +	int ret;
>>>>> +	const struct intel_plane_state *old_linked_state;
>>>>> +	struct intel_plane_state *new_linked_state = NULL;
>>>>> +
>>>>> +	if (linked) {
>>>>> +		/*
>>>>> +		* Make sure a previously linked plane (and implicitly, the CRTC)
>>>>> +		* is part of the atomic commit.
>>>>> +		*/
>>>>> +		if (!intel_atomic_get_new_plane_state(state, linked)) {
>>>>> +			new_linked_state = intel_atomic_get_plane_state(state, linked);
>>>>> +			if (IS_ERR(new_linked_state))
>>>>> +				return PTR_ERR(new_linked_state);
>>>>> +		}
>>>>> +
>>>>> +		old_linked_state =
>>>>> +			intel_atomic_get_old_plane_state(state, linked);
>>>>> +
>>>>> +		/*
>>>>> +		 * This will happen when we're the Y plane. In which case
>>>>> +		 * old/new_state->crtc are both NULL. We still need to perform
>>>>> +		 * updates on the linked plane.
>>>>> +		 */
>>>>> +		if (!crtc)
>>>>> +			crtc = to_intel_crtc(old_linked_state->base.crtc);
>>>>> +
>>>>> +		WARN_ON(!crtc);
>>>>> +	}
>>>>> +
>>>>> +	new_plane_state->base.visible = false;
>>>>>  	if (!crtc)
>>>>>  		return 0;
>>>>>  
>>>>> -	old_crtc_state = drm_atomic_get_old_crtc_state(state, crtc);
>>>>> -	new_crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
>>>>> +	old_crtc_state = intel_atomic_get_old_crtc_state(state, crtc);
>>>>> +	new_crtc_state = intel_atomic_get_new_crtc_state(state, crtc);
>>>>> +
>>>>> +	if (new_linked_state &&
>>>>> +	    drm_plane_index(&linked->base) < drm_plane_index(&plane->base)) {
>>>>> +		/*
>>>>> +		 * This function is called from drm_atomic_helper_check_planes(), which
>>>>> +		 * will normally check the newly added plane for us, but since we're
>>>>> +		 * already in that function, it won't check the plane if our index
>>>>> +		 * is bigger than the linked index because of the
>>>>> +		 * for_each_oldnew_plane_in_state() call.
>>>>> +		 */
>>>>> +		new_crtc_state->base.planes_changed = true;
>>>>> +		ret = intel_plane_atomic_check_with_state(old_crtc_state, new_crtc_state,
>>>>> +							  old_linked_state, new_linked_state);
>>>>> +		if (ret)
>>>>> +			return ret;
>>>>> +	}
>>>> This is all rather confusing. Can't we just do a preprocessing step
>>>> before check_planes() to add the linked planes as needed, and then
>>>> let the normal check_planes() do its thing?
>>> Also one thing that slightly worries me is what happens if someone adds
>>> more planes to the state after this has all been done. I guess
>>> currently those cases would either come from the tail end of
>>> intel_atomic_check() or from intel_crtc_atomic_check(). Currently it
>>> would appear that wm/ddb is the only piece of code that can do this
>>> sort of thing.
>> I think this shouldn't happen, and WM is special. The only time where you want to add more planes is before check_planes().
>> Otherwise you can't rerun any validation as required.
> You shouldn't need validation for eg. dpms on/off. I guess we currently
> do that although we shouldn't have to.
We should, if we ever have 2 crtc's active and disable 1. Watermarks should be
distributed over active planes only, which dpms toggle affects. Only way around setting
plane_state->visible when plane is inactive and calculate minimum requirements, then
calculate max requirements.

We would have to fix up all of wm programming and plane programming to make it work.

I don't think the extra complexity is worth the effort, tbh..
>> I've now added a function icl_add_linked_planes helper that iterates over all planes in
>> the state, and adds any linked planes to the transaction.
>>
>> This is run right before drm_atomic_helper_check_planes(), so we're sure that all linked
>> planes are added, without doing it from intel_plane_atomic_check()
>>
>> WM will continue to do its own thing, since it's a design error IMO that it even adds
>> planes to the state to begin with. :)
> It pretty much has to. The design error we have at the moment is not
> programming the watermarks from the update_plane()/disable_plane().
> That one I've attempted to fix in:
> git://github.com/vsyrjala/linux.git skl_plane_update_ddb_sequence
>
> And supposedly that one does fix bugs related to watermarks vs.
> plane updates.

Yeah, fortunately it shouldn't affect this code much, should be easy to rebase. :)
Though I would like to get rid of skl_next_plane_to_commit, ugh..

Which is probably a confirmation that the nv12 gen11 series isn't making plane programming
that much more complicated, fortunately.

I would really like to simplify the locking first at some point. It can't be good to sync write everything.

each plane update now does:

spin_lock()
I915_WRITE_FW(...)

POSTING_READ()
spin_unlock()

Would be nice if we 

~Maarten

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