drm/i915: setup scalers for crtc_compute_config

Added intel_atomic_setup_scalers to setup scalers based on
staged scaling requests from a crtc and its planes. If staged
requests are supportable, this function assigns scalers to
requested planes and crtc. Note that the scaler assignement
itself is staged into crtc_state and respective plane_states
for later commit after all checks have been done.

overall high level flow:
 - scaler requests are staged into crtc_state by planes/crtc
 - check whether staged scaling requests can be supported
 - add planes using scalers that aren't in current transaction
 - assign scalers to requested users
 - as part of plane commit, scalers will be committed
   (i.e., either attached or detached) to respective planes in hw
 - as part of crtc_commit, scaler will be either attached or detached
   to crtc in hw

crtc_compute_config calls intel_atomic_setup_scalers() to start
scaler assignments as per scaler state in crtc config. This call
should be moved to atomic crtc once it is available.

v2:
-removed a log message (me)
-changed input parameter to crtc_state (me)

v3:
-remove assigning plane_state returned by drm_atomic_get_plane_state (Matt)
-fail if there is an error from drm_atomic_get_plane_state (Matt)

v4:
-changes to align with updated scaler structure (Matt, me)

v5:
-added addtional checks before enabling HQ mode (me)
-added comments to enable HQ mode (Matt)
Signed-off-by: Chandra Konduru <chandra.konduru@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_atomic.c

@@ -243,3 +243,151 @@ intel_crtc_destroy_state(struct drm_crtc *crtc,
 {
 	drm_atomic_helper_crtc_destroy_state(crtc, state);
 }
+
+/**
+ * intel_atomic_setup_scalers() - setup scalers for crtc per staged requests
+ * @dev: DRM device
+ * @crtc: intel crtc
+ * @crtc_state: incoming crtc_state to validate and setup scalers
+ *
+ * This function sets up scalers based on staged scaling requests for
+ * a @crtc and its planes. It is called from crtc level check path. If request
+ * is a supportable request, it attaches scalers to requested planes and crtc.
+ *
+ * This function takes into account the current scaler(s) in use by any planes
+ * not being part of this atomic state
+ *
+ *  Returns:
+ *         0 - scalers were setup succesfully
+ *         error code - otherwise
+ */
+int intel_atomic_setup_scalers(struct drm_device *dev,
+	struct intel_crtc *intel_crtc,
+	struct intel_crtc_state *crtc_state)
+{
+	struct drm_plane *plane = NULL;
+	struct intel_plane *intel_plane;
+	struct intel_plane_state *plane_state = NULL;
+	struct intel_crtc_scaler_state *scaler_state;
+	struct drm_atomic_state *drm_state;
+	int num_scalers_need;
+	int i, j;
+
+	if (INTEL_INFO(dev)->gen < 9 || !intel_crtc || !crtc_state)
+		return 0;
+
+	scaler_state = &crtc_state->scaler_state;
+	drm_state = crtc_state->base.state;
+
+	num_scalers_need = hweight32(scaler_state->scaler_users);
+	DRM_DEBUG_KMS("crtc_state = %p need = %d avail = %d scaler_users = 0x%x\n",
+		crtc_state, num_scalers_need, intel_crtc->num_scalers,
+		scaler_state->scaler_users);
+
+	/*
+	 * High level flow:
+	 * - staged scaler requests are already in scaler_state->scaler_users
+	 * - check whether staged scaling requests can be supported
+	 * - add planes using scalers that aren't in current transaction
+	 * - assign scalers to requested users
+	 * - as part of plane commit, scalers will be committed
+	 *   (i.e., either attached or detached) to respective planes in hw
+	 * - as part of crtc_commit, scaler will be either attached or detached
+	 *   to crtc in hw
+	 */
+
+	/* fail if required scalers > available scalers */
+	if (num_scalers_need > intel_crtc->num_scalers){
+		DRM_DEBUG_KMS("Too many scaling requests %d > %d\n",
+			num_scalers_need, intel_crtc->num_scalers);
+		return -EINVAL;
+	}
+
+	/* walkthrough scaler_users bits and start assigning scalers */
+	for (i = 0; i < sizeof(scaler_state->scaler_users) * 8; i++) {
+		int *scaler_id;
+
+		/* skip if scaler not required */
+		if (!(scaler_state->scaler_users & (1 << i)))
+			continue;
+
+		if (i == SKL_CRTC_INDEX) {
+			/* panel fitter case: assign as a crtc scaler */
+			scaler_id = &scaler_state->scaler_id;
+		} else {
+			if (!drm_state)
+				continue;
+
+			/* plane scaler case: assign as a plane scaler */
+			/* find the plane that set the bit as scaler_user */
+			plane = drm_state->planes[i];
+
+			/*
+			 * to enable/disable hq mode, add planes that are using scaler
+			 * into this transaction
+			 */
+			if (!plane) {
+				struct drm_plane_state *state;
+				plane = drm_plane_from_index(dev, i);
+				state = drm_atomic_get_plane_state(drm_state, plane);
+				if (IS_ERR(state)) {
+					DRM_DEBUG_KMS("Failed to add [PLANE:%d] to drm_state\n",
+						plane->base.id);
+					return PTR_ERR(state);
+				}
+			}
+
+			intel_plane = to_intel_plane(plane);
+
+			/* plane on different crtc cannot be a scaler user of this crtc */
+			if (WARN_ON(intel_plane->pipe != intel_crtc->pipe)) {
+				continue;
+			}
+
+			plane_state = to_intel_plane_state(drm_state->plane_states[i]);
+			scaler_id = &plane_state->scaler_id;
+		}
+
+		if (*scaler_id < 0) {
+			/* find a free scaler */
+			for (j = 0; j < intel_crtc->num_scalers; j++) {
+				if (!scaler_state->scalers[j].in_use) {
+					scaler_state->scalers[j].in_use = 1;
+					*scaler_id = scaler_state->scalers[j].id;
+					DRM_DEBUG_KMS("Attached scaler id %u.%u to %s:%d\n",
+						intel_crtc->pipe,
+						i == SKL_CRTC_INDEX ? scaler_state->scaler_id :
+							plane_state->scaler_id,
+						i == SKL_CRTC_INDEX ? "CRTC" : "PLANE",
+						i == SKL_CRTC_INDEX ?  intel_crtc->base.base.id :
+						plane->base.id);
+					break;
+				}
+			}
+		}
+
+		if (WARN_ON(*scaler_id < 0)) {
+			DRM_DEBUG_KMS("Cannot find scaler for %s:%d\n",
+				i == SKL_CRTC_INDEX ? "CRTC" : "PLANE",
+				i == SKL_CRTC_INDEX ? intel_crtc->base.base.id:plane->base.id);
+			continue;
+		}
+
+		/* set scaler mode */
+		if (num_scalers_need == 1 && intel_crtc->pipe != PIPE_C) {
+			/*
+			 * when only 1 scaler is in use on either pipe A or B,
+			 * scaler 0 operates in high quality (HQ) mode.
+			 * In this case use scaler 0 to take advantage of HQ mode
+			 */
+			*scaler_id = 0;
+			scaler_state->scalers[0].in_use = 1;
+			scaler_state->scalers[0].mode = PS_SCALER_MODE_HQ;
+			scaler_state->scalers[1].in_use = 0;
+		} else {
+			scaler_state->scalers[*scaler_id].mode = PS_SCALER_MODE_DYN;
+		}
+	}
+
+	return 0;
+}

drivers/gpu/drm/i915/intel_display.c

@@ -5886,6 +5886,7 @@ static int intel_crtc_compute_config(struct intel_crtc *crtc,
 	struct drm_device *dev = crtc->base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_display_mode *adjusted_mode = &pipe_config->base.adjusted_mode;
+	int ret;
 
 	/* FIXME should check pixel clock limits on all platforms */
 	if (INTEL_INFO(dev)->gen < 4) {
@@ -5940,7 +5941,14 @@ static int intel_crtc_compute_config(struct intel_crtc *crtc,
 	if (pipe_config->has_pch_encoder)
 		return ironlake_fdi_compute_config(crtc, pipe_config);
 
-	return 0;
+	/* FIXME: remove below call once atomic mode set is place and all crtc
+	 * related checks called from atomic_crtc_check function */
+	ret = 0;
+	DRM_DEBUG_KMS("intel_crtc = %p drm_state (pipe_config->base.state) = %p\n",
+		crtc, pipe_config->base.state);
+	ret = intel_atomic_setup_scalers(dev, crtc, pipe_config);
+
+	return ret;
 }
 
 static int skylake_get_display_clock_speed(struct drm_device *dev)

drivers/gpu/drm/i915/intel_drv.h

@@ -1392,6 +1392,9 @@ intel_atomic_get_crtc_state(struct drm_atomic_state *state,
 
 	return to_intel_crtc_state(crtc_state);
 }
+int intel_atomic_setup_scalers(struct drm_device *dev,
+	struct intel_crtc *intel_crtc,
+	struct intel_crtc_state *crtc_state);
 
 /* intel_atomic_plane.c */
 struct intel_plane_state *intel_create_plane_state(struct drm_plane *plane);