Re: [PATCH v3 15/19] drm/i915: atomic plane updates in a nutshell

[Maarten Lankhorst <maarten.lankhorst@linux.intel.com>]

Op 18-06-15 om 17:28 schreef Ville Syrjälä:
> On Mon, Jun 15, 2015 at 12:33:52PM +0200, Maarten Lankhorst wrote:
>> Now that all planes are added during a modeset we can use the
>> calculated changes before disabling a plane, and then either commit
>> or force disable a plane before disabling the crtc.
>>
>> The code is shared with atomic_begin/flush, except watermark updating
>> and vblank evasion are not used.
>>
>> This is needed for proper atomic suspend/resume support.
>>
>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90868
>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>> ---
>>  drivers/gpu/drm/i915/intel_display.c | 103 ++++++++---------------------------
>>  drivers/gpu/drm/i915/intel_sprite.c  |   4 +-
>>  2 files changed, 23 insertions(+), 84 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>> index cc4ca4970716..beb69281f45c 100644
>> --- a/drivers/gpu/drm/i915/intel_display.c
>> +++ b/drivers/gpu/drm/i915/intel_display.c
>> @@ -2217,28 +2217,6 @@ static void intel_disable_pipe(struct intel_crtc *crtc)
>>  		intel_wait_for_pipe_off(crtc);
>>  }
>>  
>> -/**
>> - * intel_enable_primary_hw_plane - enable the primary plane on a given pipe
>> - * @plane:  plane to be enabled
>> - * @crtc: crtc for the plane
>> - *
>> - * Enable @plane on @crtc, making sure that the pipe is running first.
>> - */
>> -static void intel_enable_primary_hw_plane(struct drm_plane *plane,
>> -					  struct drm_crtc *crtc)
>> -{
>> -	struct drm_device *dev = plane->dev;
>> -	struct drm_i915_private *dev_priv = dev->dev_private;
>> -	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
>> -
>> -	/* If the pipe isn't enabled, we can't pump pixels and may hang */
>> -	assert_pipe_enabled(dev_priv, intel_crtc->pipe);
>> -	to_intel_plane_state(plane->state)->visible = true;
>> -
>> -	dev_priv->display.update_primary_plane(crtc, plane->fb,
>> -					       crtc->x, crtc->y);
>> -}
>> -
>>  static bool need_vtd_wa(struct drm_device *dev)
>>  {
>>  #ifdef CONFIG_INTEL_IOMMU
>> @@ -4508,20 +4486,6 @@ static void ironlake_pfit_enable(struct intel_crtc *crtc)
>>  	}
>>  }
>>  
>> -static void intel_enable_sprite_planes(struct drm_crtc *crtc)
>> -{
>> -	struct drm_device *dev = crtc->dev;
>> -	enum pipe pipe = to_intel_crtc(crtc)->pipe;
>> -	struct drm_plane *plane;
>> -	struct intel_plane *intel_plane;
>> -
>> -	drm_for_each_legacy_plane(plane, &dev->mode_config.plane_list) {
>> -		intel_plane = to_intel_plane(plane);
>> -		if (intel_plane->pipe == pipe)
>> -			intel_plane_restore(&intel_plane->base);
>> -	}
>> -}
>> -
>>  void hsw_enable_ips(struct intel_crtc *crtc)
>>  {
>>  	struct drm_device *dev = crtc->base.dev;
>> @@ -4817,27 +4781,6 @@ static void intel_pre_plane_update(struct intel_crtc *crtc)
>>  		intel_pre_disable_primary(&crtc->base);
>>  }
>>  
>> -static void intel_crtc_enable_planes(struct drm_crtc *crtc)
>> -{
>> -	struct drm_device *dev = crtc->dev;
>> -	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
>> -	int pipe = intel_crtc->pipe;
>> -
>> -	intel_enable_primary_hw_plane(crtc->primary, crtc);
>> -	intel_enable_sprite_planes(crtc);
>> -	if (to_intel_plane_state(crtc->cursor->state)->visible)
>> -		intel_crtc_update_cursor(crtc, true);
>> -
>> -	intel_post_enable_primary(crtc);
>> -
>> -	/*
>> -	 * FIXME: Once we grow proper nuclear flip support out of this we need
>> -	 * to compute the mask of flip planes precisely. For the time being
>> -	 * consider this a flip to a NULL plane.
>> -	 */
>> -	intel_frontbuffer_flip(dev, INTEL_FRONTBUFFER_ALL_MASK(pipe));
>> -}
>> -
>>  static void intel_crtc_disable_planes(struct drm_crtc *crtc, unsigned plane_mask)
>>  {
>>  	struct drm_device *dev = crtc->dev;
>> @@ -4845,10 +4788,6 @@ static void intel_crtc_disable_planes(struct drm_crtc *crtc, unsigned plane_mask
>>  	struct drm_plane *p;
>>  	int pipe = intel_crtc->pipe;
>>  
>> -	intel_crtc_wait_for_pending_flips(crtc);
>> -
>> -	intel_pre_disable_primary(crtc);
>> -
>>  	intel_crtc_dpms_overlay_disable(intel_crtc);
>>  
>>  	drm_for_each_plane_mask(p, dev, plane_mask)
>> @@ -6270,6 +6209,11 @@ static void intel_crtc_disable_noatomic(struct drm_crtc *crtc)
>>  	if (!intel_crtc->active)
>>  		return;
>>  
>> +	if (to_intel_plane_state(crtc->primary->state)->visible) {
>> +		intel_crtc_wait_for_pending_flips(crtc);
>> +		intel_pre_disable_primary(crtc);
>> +	}
>> +
>>  	intel_crtc_disable_planes(crtc, crtc->state->plane_mask);
>>  	dev_priv->display.crtc_disable(crtc);
>>  
>> @@ -11783,10 +11727,6 @@ int intel_plane_atomic_calc_changes(struct drm_crtc_state *crtc_state,
>>  	if (old_plane_state->base.fb && !fb)
>>  		intel_crtc->atomic.disabled_planes |= 1 << i;
>>  
>> -	/* don't run rest during modeset yet */
>> -	if (!intel_crtc->active || mode_changed)
>> -		return 0;
>> -
>>  	was_visible = old_plane_state->visible;
>>  	visible = to_intel_plane_state(plane_state)->visible;
>>  
>> @@ -13255,15 +13195,18 @@ static int __intel_set_mode(struct drm_atomic_state *state)
>>  	drm_atomic_helper_swap_state(dev, state);
>>  
>>  	for_each_crtc_in_state(state, crtc, crtc_state, i) {
>> +		struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
>> +
>>  		if (!needs_modeset(crtc->state))
>>  			continue;
>>  
>>  		any_ms = true;
>> -		if (!crtc_state->active)
>> -			continue;
>> +		intel_pre_plane_update(intel_crtc);
>>  
>> -		intel_crtc_disable_planes(crtc, crtc_state->plane_mask);
>> -		dev_priv->display.crtc_disable(crtc);
>> +		if (crtc_state->active) {
>> +			intel_crtc_disable_planes(crtc, crtc_state->plane_mask);
>> +			dev_priv->display.crtc_disable(crtc);
>> +		}
>>  	}
>>  
>>  	/* Only after disabling all output pipelines that will be changed can we
>> @@ -13277,15 +13220,12 @@ static int __intel_set_mode(struct drm_atomic_state *state)
>>  
>>  	/* Now enable the clocks, plane, pipe, and connectors that we set up. */
>>  	for_each_crtc_in_state(state, crtc, crtc_state, i) {
>> -		drm_atomic_helper_commit_planes_on_crtc(crtc_state);
>> -
>> -		if (!needs_modeset(crtc->state) || !crtc->state->active)
>> -			continue;
>> -
>> -		update_scanline_offset(to_intel_crtc(crtc));
>> +		if (needs_modeset(crtc->state) && crtc->state->active) {
>> +			update_scanline_offset(to_intel_crtc(crtc));
>> +			dev_priv->display.crtc_enable(crtc);
>> +		}
>>  
>> -		dev_priv->display.crtc_enable(crtc);
>> -		intel_crtc_enable_planes(crtc);
>> +		drm_atomic_helper_commit_planes_on_crtc(crtc_state);
> Why are we still commiting planes on a disabled pipes?
>
> The way I envisioned the modeset path looking is something like this:
>
> 1. atomically disable all planes for pipes getting disabled
> 2. disable all pipes that need disabling
> 3. enable all pipes that need enabling
> 4. atomically update all planes that require it on now active pipes
>
>
I looked for other ways to do this, but they were ugly. Only updating sw state in commit_planes for disabled crtc's made things a lot cleaner without worrying about special cases.

plane_disable doesn't update sw state, so it performs 1. The commit function is still called because update plane->fb
needs to be updated, even for disabled crtc's. Conditionally calling plane_commit caused more issues than it solved.

~Maarten
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