drm/i915: rip out intel_crtc->dpms_mode

Afaict this has been used for two things:
- To prevent the crtc enable code from being run twice. We have now
  intel_crtc->active to track this in a more precise way.
- To ensure the code copes correctly with the unknown hw state after
  boot and resume. Thanks to the hw state readout and sanitize code we
  have now a better way to handle this.

The only thing it still does is complicate our modeset state space.

Having outlived its usefullness, let it just die.
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -3470,18 +3470,10 @@ void intel_crtc_update_dpms(struct drm_crtc *crtc)
 	struct intel_encoder *intel_encoder;
 	int pipe = intel_crtc->pipe;
 	bool enabled, enable = false;
-	int mode;
 
 	for_each_encoder_on_crtc(dev, crtc, intel_encoder)
 		enable |= intel_encoder->connectors_active;
 
-	mode = enable ? DRM_MODE_DPMS_ON : DRM_MODE_DPMS_OFF;
-
-	if (intel_crtc->dpms_mode == mode)
-		return;
-
-	intel_crtc->dpms_mode = mode;
-
 	if (enable)
 		dev_priv->display.crtc_enable(crtc);
 	else
@@ -5037,11 +5029,6 @@ static int intel_crtc_mode_set(struct drm_crtc *crtc,
 					      x, y, old_fb);
 	drm_vblank_post_modeset(dev, pipe);
 
-	if (ret)
-		intel_crtc->dpms_mode = DRM_MODE_DPMS_OFF;
-	else
-		intel_crtc->dpms_mode = DRM_MODE_DPMS_ON;
-
 	return ret;
 }
 
@@ -7621,10 +7608,6 @@ static void intel_sanitize_crtc(struct intel_crtc *crtc)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	u32 reg, val;
 
-	/* Clear the dpms state for compatibility with code still using that
-	 * deprecated state variable. */
-	crtc->dpms_mode = -1;
-
 	/* Clear any frame start delays used for debugging left by the BIOS */
 	reg = PIPECONF(crtc->pipe);
 	I915_WRITE(reg, I915_READ(reg) & ~PIPECONF_FRAME_START_DELAY_MASK);

drivers/gpu/drm/i915/intel_drv.h

@@ -164,7 +164,6 @@ struct intel_crtc {
 	enum pipe pipe;
 	enum plane plane;
 	u8 lut_r[256], lut_g[256], lut_b[256];
-	int dpms_mode;
 	/*
 	 * Whether the crtc and the connected output pipeline is active. Implies
 	 * that crtc->enabled is set, i.e. the current mode configuration has