drm/i915/dsb: Pre allocate and late cleanup of cmd buffer

Pre-allocate command buffer in atomic_commit using intel_dsb_prepare
function which also includes pinning and map in cpu domain.

No functional change is dsb write/commit functions.

Now dsb get/put function is removed and ref-count mechanism is
not needed. Below dsb api added to do respective job mentioned
below.

intel_dsb_prepare - Allocate, pin and map the buffer.
intel_dsb_cleanup - Unpin and release the gem object.

RFC: Initial patch for design review.
v2: included _init() part in _prepare(). [Daniel, Ville]
v3: dsb_cleanup called after cleanup_planes. [Daniel]
v4: dsb structure is moved to intel_crtc_state from intel_crtc. [Maarten]
v5: dsb get/put/ref-count mechanism removed. [Maarten]
v6: Based on review feedback following changes are added,
- replaced intel_dsb structure by pointer in intel_crtc_state. [Maarten]
- passing intel_crtc_state to dsp-api to simplify the code. [Maarten]
- few dsb functions prototype modified to simplify code.
v7: added few cosmetic changes suggested by Jani and null check for
crtc_state in dsb_cleanup removed as suggested by Maarten.
v8: changed the function parameter to intel_crtc_state* of
ivb_load_lut_ext_max() from intel_crtc. [Maarten]
v9: error handling improved in _write() and prepare(). [Maarten]

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200520130737.11240-1-animesh.manna@intel.com

drivers/gpu/drm/i915/display/intel_atomic.c

@@ -252,6 +252,7 @@ intel_crtc_duplicate_state(struct drm_crtc *crtc)
 	crtc_state->wm.need_postvbl_update = false;
 	crtc_state->fb_bits = 0;
 	crtc_state->update_planes = 0;
+	crtc_state->dsb = NULL;
 
 	return &crtc_state->uapi;
 }
@@ -292,6 +293,8 @@ intel_crtc_destroy_state(struct drm_crtc *crtc,
 {
 	struct intel_crtc_state *crtc_state = to_intel_crtc_state(state);
 
+	drm_WARN_ON(crtc->dev, crtc_state->dsb);
+
 	__drm_atomic_helper_crtc_destroy_state(&crtc_state->uapi);
 	intel_crtc_free_hw_state(crtc_state);
 	kfree(crtc_state);

drivers/gpu/drm/i915/display/intel_color.c

@@ -714,16 +714,16 @@ static void bdw_load_lut_10(struct intel_crtc *crtc,
 	intel_de_write(dev_priv, PREC_PAL_INDEX(pipe), 0);
 }
 
-static void ivb_load_lut_ext_max(struct intel_crtc *crtc)
+static void ivb_load_lut_ext_max(const struct intel_crtc_state *crtc_state)
 {
+	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
-	struct intel_dsb *dsb = intel_dsb_get(crtc);
 	enum pipe pipe = crtc->pipe;
 
 	/* Program the max register to clamp values > 1.0. */
-	intel_dsb_reg_write(dsb, PREC_PAL_EXT_GC_MAX(pipe, 0), 1 << 16);
-	intel_dsb_reg_write(dsb, PREC_PAL_EXT_GC_MAX(pipe, 1), 1 << 16);
-	intel_dsb_reg_write(dsb, PREC_PAL_EXT_GC_MAX(pipe, 2), 1 << 16);
+	intel_dsb_reg_write(crtc_state, PREC_PAL_EXT_GC_MAX(pipe, 0), 1 << 16);
+	intel_dsb_reg_write(crtc_state, PREC_PAL_EXT_GC_MAX(pipe, 1), 1 << 16);
+	intel_dsb_reg_write(crtc_state, PREC_PAL_EXT_GC_MAX(pipe, 2), 1 << 16);
 
 	/*
 	 * Program the gc max 2 register to clamp values > 1.0.
@@ -731,15 +731,13 @@ static void ivb_load_lut_ext_max(struct intel_crtc *crtc)
 	 * from 3.0 to 7.0
 	 */
 	if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv)) {
-		intel_dsb_reg_write(dsb, PREC_PAL_EXT2_GC_MAX(pipe, 0),
+		intel_dsb_reg_write(crtc_state, PREC_PAL_EXT2_GC_MAX(pipe, 0),
 				    1 << 16);
-		intel_dsb_reg_write(dsb, PREC_PAL_EXT2_GC_MAX(pipe, 1),
+		intel_dsb_reg_write(crtc_state, PREC_PAL_EXT2_GC_MAX(pipe, 1),
 				    1 << 16);
-		intel_dsb_reg_write(dsb, PREC_PAL_EXT2_GC_MAX(pipe, 2),
+		intel_dsb_reg_write(crtc_state, PREC_PAL_EXT2_GC_MAX(pipe, 2),
 				    1 << 16);
 	}
-
-	intel_dsb_put(dsb);
 }
 
 static void ivb_load_luts(const struct intel_crtc_state *crtc_state)
@@ -753,7 +751,7 @@ static void ivb_load_luts(const struct intel_crtc_state *crtc_state)
 	} else if (crtc_state->gamma_mode == GAMMA_MODE_MODE_SPLIT) {
 		ivb_load_lut_10(crtc, degamma_lut, PAL_PREC_SPLIT_MODE |
 				PAL_PREC_INDEX_VALUE(0));
-		ivb_load_lut_ext_max(crtc);
+		ivb_load_lut_ext_max(crtc_state);
 		ivb_load_lut_10(crtc, gamma_lut, PAL_PREC_SPLIT_MODE |
 				PAL_PREC_INDEX_VALUE(512));
 	} else {
@@ -761,7 +759,7 @@ static void ivb_load_luts(const struct intel_crtc_state *crtc_state)
 
 		ivb_load_lut_10(crtc, blob,
 				PAL_PREC_INDEX_VALUE(0));
-		ivb_load_lut_ext_max(crtc);
+		ivb_load_lut_ext_max(crtc_state);
 	}
 }
 
@@ -776,7 +774,7 @@ static void bdw_load_luts(const struct intel_crtc_state *crtc_state)
 	} else if (crtc_state->gamma_mode == GAMMA_MODE_MODE_SPLIT) {
 		bdw_load_lut_10(crtc, degamma_lut, PAL_PREC_SPLIT_MODE |
 				PAL_PREC_INDEX_VALUE(0));
-		ivb_load_lut_ext_max(crtc);
+		ivb_load_lut_ext_max(crtc_state);
 		bdw_load_lut_10(crtc, gamma_lut, PAL_PREC_SPLIT_MODE |
 				PAL_PREC_INDEX_VALUE(512));
 	} else {
@@ -784,7 +782,7 @@ static void bdw_load_luts(const struct intel_crtc_state *crtc_state)
 
 		bdw_load_lut_10(crtc, blob,
 				PAL_PREC_INDEX_VALUE(0));
-		ivb_load_lut_ext_max(crtc);
+		ivb_load_lut_ext_max(crtc_state);
 	}
 }
 
@@ -877,7 +875,7 @@ static void glk_load_luts(const struct intel_crtc_state *crtc_state)
 		ilk_load_lut_8(crtc, gamma_lut);
 	} else {
 		bdw_load_lut_10(crtc, gamma_lut, PAL_PREC_INDEX_VALUE(0));
-		ivb_load_lut_ext_max(crtc);
+		ivb_load_lut_ext_max(crtc_state);
 	}
 }
 
@@ -900,14 +898,12 @@ icl_load_gcmax(const struct intel_crtc_state *crtc_state,
 	       const struct drm_color_lut *color)
 {
 	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
-	struct intel_dsb *dsb = intel_dsb_get(crtc);
 	enum pipe pipe = crtc->pipe;
 
 	/* FIXME LUT entries are 16 bit only, so we can prog 0xFFFF max */
-	intel_dsb_reg_write(dsb, PREC_PAL_GC_MAX(pipe, 0), color->red);
-	intel_dsb_reg_write(dsb, PREC_PAL_GC_MAX(pipe, 1), color->green);
-	intel_dsb_reg_write(dsb, PREC_PAL_GC_MAX(pipe, 2), color->blue);
-	intel_dsb_put(dsb);
+	intel_dsb_reg_write(crtc_state, PREC_PAL_GC_MAX(pipe, 0), color->red);
+	intel_dsb_reg_write(crtc_state, PREC_PAL_GC_MAX(pipe, 1), color->green);
+	intel_dsb_reg_write(crtc_state, PREC_PAL_GC_MAX(pipe, 2), color->blue);
 }
 
 static void
@@ -916,7 +912,6 @@ icl_program_gamma_superfine_segment(const struct intel_crtc_state *crtc_state)
 	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
 	const struct drm_property_blob *blob = crtc_state->hw.gamma_lut;
 	const struct drm_color_lut *lut = blob->data;
-	struct intel_dsb *dsb = intel_dsb_get(crtc);
 	enum pipe pipe = crtc->pipe;
 	int i;
 
@@ -927,19 +922,17 @@ icl_program_gamma_superfine_segment(const struct intel_crtc_state *crtc_state)
 	 * 9 entries, corresponding to values 0, 1/(8 * 128 * 256),
 	 * 2/(8 * 128 * 256) ... 8/(8 * 128 * 256).
 	 */
-	intel_dsb_reg_write(dsb, PREC_PAL_MULTI_SEG_INDEX(pipe),
+	intel_dsb_reg_write(crtc_state, PREC_PAL_MULTI_SEG_INDEX(pipe),
 			    PAL_PREC_AUTO_INCREMENT);
 
 	for (i = 0; i < 9; i++) {
 		const struct drm_color_lut *entry = &lut[i];
 
-		intel_dsb_indexed_reg_write(dsb, PREC_PAL_MULTI_SEG_DATA(pipe),
+		intel_dsb_indexed_reg_write(crtc_state, PREC_PAL_MULTI_SEG_DATA(pipe),
 					    ilk_lut_12p4_ldw(entry));
-		intel_dsb_indexed_reg_write(dsb, PREC_PAL_MULTI_SEG_DATA(pipe),
+		intel_dsb_indexed_reg_write(crtc_state, PREC_PAL_MULTI_SEG_DATA(pipe),
 					    ilk_lut_12p4_udw(entry));
 	}
-
-	intel_dsb_put(dsb);
 }
 
 static void
@@ -949,7 +942,6 @@ icl_program_gamma_multi_segment(const struct intel_crtc_state *crtc_state)
 	const struct drm_property_blob *blob = crtc_state->hw.gamma_lut;
 	const struct drm_color_lut *lut = blob->data;
 	const struct drm_color_lut *entry;
-	struct intel_dsb *dsb = intel_dsb_get(crtc);
 	enum pipe pipe = crtc->pipe;
 	int i;
 
@@ -963,12 +955,13 @@ icl_program_gamma_multi_segment(const struct intel_crtc_state *crtc_state)
 	 * PAL_PREC_INDEX[0] and PAL_PREC_INDEX[1] map to seg2[1],
 	 * seg2[0] being unused by the hardware.
 	 */
-	intel_dsb_reg_write(dsb, PREC_PAL_INDEX(pipe), PAL_PREC_AUTO_INCREMENT);
+	intel_dsb_reg_write(crtc_state, PREC_PAL_INDEX(pipe),
+			    PAL_PREC_AUTO_INCREMENT);
 	for (i = 1; i < 257; i++) {
 		entry = &lut[i * 8];
-		intel_dsb_indexed_reg_write(dsb, PREC_PAL_DATA(pipe),
+		intel_dsb_indexed_reg_write(crtc_state, PREC_PAL_DATA(pipe),
 					    ilk_lut_12p4_ldw(entry));
-		intel_dsb_indexed_reg_write(dsb, PREC_PAL_DATA(pipe),
+		intel_dsb_indexed_reg_write(crtc_state, PREC_PAL_DATA(pipe),
 					    ilk_lut_12p4_udw(entry));
 	}
 
@@ -986,24 +979,22 @@ icl_program_gamma_multi_segment(const struct intel_crtc_state *crtc_state)
 	 */
 	for (i = 0; i < 256; i++) {
 		entry = &lut[i * 8 * 128];
-		intel_dsb_indexed_reg_write(dsb, PREC_PAL_DATA(pipe),
+		intel_dsb_indexed_reg_write(crtc_state, PREC_PAL_DATA(pipe),
 					    ilk_lut_12p4_ldw(entry));
-		intel_dsb_indexed_reg_write(dsb, PREC_PAL_DATA(pipe),
+		intel_dsb_indexed_reg_write(crtc_state, PREC_PAL_DATA(pipe),
 					    ilk_lut_12p4_udw(entry));
 	}
 
 	/* The last entry in the LUT is to be programmed in GCMAX */
 	entry = &lut[256 * 8 * 128];
 	icl_load_gcmax(crtc_state, entry);
-	ivb_load_lut_ext_max(crtc);
-	intel_dsb_put(dsb);
+	ivb_load_lut_ext_max(crtc_state);
 }
 
 static void icl_load_luts(const struct intel_crtc_state *crtc_state)
 {
 	const struct drm_property_blob *gamma_lut = crtc_state->hw.gamma_lut;
 	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
-	struct intel_dsb *dsb = intel_dsb_get(crtc);
 
 	if (crtc_state->hw.degamma_lut)
 		glk_load_degamma_lut(crtc_state);
@@ -1018,11 +1009,10 @@ static void icl_load_luts(const struct intel_crtc_state *crtc_state)
 		break;
 	default:
 		bdw_load_lut_10(crtc, gamma_lut, PAL_PREC_INDEX_VALUE(0));
-		ivb_load_lut_ext_max(crtc);
+		ivb_load_lut_ext_max(crtc_state);
 	}
 
-	intel_dsb_commit(dsb);
-	intel_dsb_put(dsb);
+	intel_dsb_commit(crtc_state);
 }
 
 static u32 chv_cgm_degamma_ldw(const struct drm_color_lut *color)

drivers/gpu/drm/i915/display/intel_display.c

@@ -14996,8 +14996,24 @@ static int intel_atomic_check(struct drm_device *dev,
 
 static int intel_atomic_prepare_commit(struct intel_atomic_state *state)
 {
-	return drm_atomic_helper_prepare_planes(state->base.dev,
-						&state->base);
+	struct intel_crtc_state *crtc_state;
+	struct intel_crtc *crtc;
+	int i, ret;
+
+	ret = drm_atomic_helper_prepare_planes(state->base.dev, &state->base);
+	if (ret < 0)
+		return ret;
+
+	for_each_new_intel_crtc_in_state(state, crtc, crtc_state, i) {
+		bool mode_changed = needs_modeset(crtc_state);
+
+		if (mode_changed || crtc_state->update_pipe ||
+		    crtc_state->uapi.color_mgmt_changed) {
+			intel_dsb_prepare(crtc_state);
+		}
+	}
+
+	return 0;
 }
 
 u32 intel_crtc_get_vblank_counter(struct intel_crtc *crtc)
@@ -15427,15 +15443,27 @@ static void intel_atomic_commit_fence_wait(struct intel_atomic_state *intel_stat
 		    &wait_reset);
 }
 
+static void intel_cleanup_dsbs(struct intel_atomic_state *state)
+{
+	struct intel_crtc_state *old_crtc_state, *new_crtc_state;
+	struct intel_crtc *crtc;
+	int i;
+
+	for_each_oldnew_intel_crtc_in_state(state, crtc, old_crtc_state,
+					    new_crtc_state, i)
+		intel_dsb_cleanup(old_crtc_state);
+}
+
 static void intel_atomic_cleanup_work(struct work_struct *work)
 {
-	struct drm_atomic_state *state =
-		container_of(work, struct drm_atomic_state, commit_work);
-	struct drm_i915_private *i915 = to_i915(state->dev);
+	struct intel_atomic_state *state =
+		container_of(work, struct intel_atomic_state, base.commit_work);
+	struct drm_i915_private *i915 = to_i915(state->base.dev);
 
-	drm_atomic_helper_cleanup_planes(&i915->drm, state);
-	drm_atomic_helper_commit_cleanup_done(state);
-	drm_atomic_state_put(state);
+	intel_cleanup_dsbs(state);
+	drm_atomic_helper_cleanup_planes(&i915->drm, &state->base);
+	drm_atomic_helper_commit_cleanup_done(&state->base);
+	drm_atomic_state_put(&state->base);
 
 	intel_atomic_helper_free_state(i915);
 }
@@ -15565,6 +15593,13 @@ static void intel_atomic_commit_tail(struct intel_atomic_state *state)
 			modeset_put_power_domains(dev_priv, put_domains[i]);
 
 		intel_modeset_verify_crtc(crtc, state, old_crtc_state, new_crtc_state);
+
+		/*
+		 * DSB cleanup is done in cleanup_work aligning with framebuffer
+		 * cleanup. So copy and reset the dsb structure to sync with
+		 * commit_done and later do dsb cleanup in cleanup_work.
+		 */
+		old_crtc_state->dsb = fetch_and_zero(&new_crtc_state->dsb);
 	}
 
 	/* Underruns don't always raise interrupts, so check manually */
@@ -15714,8 +15749,15 @@ static int intel_atomic_commit(struct drm_device *dev,
 		intel_atomic_swap_global_state(state);
 
 	if (ret) {
+		struct intel_crtc_state *new_crtc_state;
+		struct intel_crtc *crtc;
+		int i;
+
 		i915_sw_fence_commit(&state->commit_ready);
 
+		for_each_new_intel_crtc_in_state(state, crtc, new_crtc_state, i)
+			intel_dsb_cleanup(new_crtc_state);
+
 		drm_atomic_helper_cleanup_planes(dev, &state->base);
 		intel_runtime_pm_put(&dev_priv->runtime_pm, state->wakeref);
 		return ret;

drivers/gpu/drm/i915/display/intel_display_types.h

@@ -1067,6 +1067,9 @@ struct intel_crtc_state {
 
 	/* Only valid on TGL+ */
 	enum transcoder mst_master_transcoder;
+
+	/* For DSB related info */
+	struct intel_dsb *dsb;
 };
 
 enum intel_pipe_crc_source {
@@ -1136,9 +1139,6 @@ struct intel_crtc {
 	/* scalers available on this crtc */
 	int num_scalers;
 
-	/* per pipe DSB related info */
-	struct intel_dsb dsb;
-
 #ifdef CONFIG_DEBUG_FS
 	struct intel_pipe_crc pipe_crc;
 #endif

drivers/gpu/drm/i915/display/intel_dsb.c

@@ -34,152 +34,52 @@
 #define DSB_BYTE_EN_SHIFT		20
 #define DSB_REG_VALUE_MASK		0xfffff
 
-static bool is_dsb_busy(struct intel_dsb *dsb)
+static bool is_dsb_busy(struct drm_i915_private *i915, enum pipe pipe,
+			enum dsb_id id)
 {
-	struct intel_crtc *crtc = container_of(dsb, typeof(*crtc), dsb);
-	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
-	enum pipe pipe = crtc->pipe;
-
-	return DSB_STATUS & intel_de_read(dev_priv, DSB_CTRL(pipe, dsb->id));
+	return DSB_STATUS & intel_de_read(i915, DSB_CTRL(pipe, id));
 }
 
-static bool intel_dsb_enable_engine(struct intel_dsb *dsb)
+static bool intel_dsb_enable_engine(struct drm_i915_private *i915,
+				    enum pipe pipe, enum dsb_id id)
 {
-	struct intel_crtc *crtc = container_of(dsb, typeof(*crtc), dsb);
-	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
-	enum pipe pipe = crtc->pipe;
 	u32 dsb_ctrl;
 
-	dsb_ctrl = intel_de_read(dev_priv, DSB_CTRL(pipe, dsb->id));
+	dsb_ctrl = intel_de_read(i915, DSB_CTRL(pipe, id));
 	if (DSB_STATUS & dsb_ctrl) {
-		drm_dbg_kms(&dev_priv->drm, "DSB engine is busy.\n");
+		drm_dbg_kms(&i915->drm, "DSB engine is busy.\n");
 		return false;
 	}
 
 	dsb_ctrl |= DSB_ENABLE;
-	intel_de_write(dev_priv, DSB_CTRL(pipe, dsb->id), dsb_ctrl);
+	intel_de_write(i915, DSB_CTRL(pipe, id), dsb_ctrl);
 
-	intel_de_posting_read(dev_priv, DSB_CTRL(pipe, dsb->id));
+	intel_de_posting_read(i915, DSB_CTRL(pipe, id));
 	return true;
 }
 
-static bool intel_dsb_disable_engine(struct intel_dsb *dsb)
+static bool intel_dsb_disable_engine(struct drm_i915_private *i915,
+				     enum pipe pipe, enum dsb_id id)
 {
-	struct intel_crtc *crtc = container_of(dsb, typeof(*crtc), dsb);
-	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
-	enum pipe pipe = crtc->pipe;
 	u32 dsb_ctrl;
 
-	dsb_ctrl = intel_de_read(dev_priv, DSB_CTRL(pipe, dsb->id));
+	dsb_ctrl = intel_de_read(i915, DSB_CTRL(pipe, id));
 	if (DSB_STATUS & dsb_ctrl) {
-		drm_dbg_kms(&dev_priv->drm, "DSB engine is busy.\n");
+		drm_dbg_kms(&i915->drm, "DSB engine is busy.\n");
 		return false;
 	}
 
 	dsb_ctrl &= ~DSB_ENABLE;
-	intel_de_write(dev_priv, DSB_CTRL(pipe, dsb->id), dsb_ctrl);
+	intel_de_write(i915, DSB_CTRL(pipe, id), dsb_ctrl);
 
-	intel_de_posting_read(dev_priv, DSB_CTRL(pipe, dsb->id));
+	intel_de_posting_read(i915, DSB_CTRL(pipe, id));
 	return true;
 }
 
-/**
- * intel_dsb_get() - Allocate DSB context and return a DSB instance.
- * @crtc: intel_crtc structure to get pipe info.
- *
- * This function provides handle of a DSB instance, for the further DSB
- * operations.
- *
- * Returns: address of Intel_dsb instance requested for.
- * Failure: Returns the same DSB instance, but without a command buffer.
- */
-
-struct intel_dsb *
-intel_dsb_get(struct intel_crtc *crtc)
-{
-	struct drm_device *dev = crtc->base.dev;
-	struct drm_i915_private *i915 = to_i915(dev);
-	struct intel_dsb *dsb = &crtc->dsb;
-	struct drm_i915_gem_object *obj;
-	struct i915_vma *vma;
-	u32 *buf;
-	intel_wakeref_t wakeref;
-
-	if (!HAS_DSB(i915))
-		return dsb;
-
-	if (dsb->refcount++ != 0)
-		return dsb;
-
-	wakeref = intel_runtime_pm_get(&i915->runtime_pm);
-
-	obj = i915_gem_object_create_internal(i915, DSB_BUF_SIZE);
-	if (IS_ERR(obj)) {
-		drm_err(&i915->drm, "Gem object creation failed\n");
-		goto out;
-	}
-
-	vma = i915_gem_object_ggtt_pin(obj, NULL, 0, 0, 0);
-	if (IS_ERR(vma)) {
-		drm_err(&i915->drm, "Vma creation failed\n");
-		i915_gem_object_put(obj);
-		goto out;
-	}
-
-	buf = i915_gem_object_pin_map(vma->obj, I915_MAP_WC);
-	if (IS_ERR(buf)) {
-		drm_err(&i915->drm, "Command buffer creation failed\n");
-		goto out;
-	}
-
-	dsb->id = DSB1;
-	dsb->vma = vma;
-	dsb->cmd_buf = buf;
-
-out:
-	/*
-	 * On error dsb->cmd_buf will continue to be NULL, making the writes
-	 * pass-through. Leave the dangling ref to be removed later by the
-	 * corresponding intel_dsb_put(): the important error message will
-	 * already be logged above.
-	 */
-
-	intel_runtime_pm_put(&i915->runtime_pm, wakeref);
-
-	return dsb;
-}
-
-/**
- * intel_dsb_put() - To destroy DSB context.
- * @dsb: intel_dsb structure.
- *
- * This function destroys the DSB context allocated by a dsb_get(), by
- * unpinning and releasing the VMA object associated with it.
- */
-
-void intel_dsb_put(struct intel_dsb *dsb)
-{
-	struct intel_crtc *crtc = container_of(dsb, typeof(*crtc), dsb);
-	struct drm_i915_private *i915 = to_i915(crtc->base.dev);
-
-	if (!HAS_DSB(i915))
-		return;
-
-	if (drm_WARN_ON(&i915->drm, dsb->refcount == 0))
-		return;
-
-	if (--dsb->refcount == 0) {
-		i915_vma_unpin_and_release(&dsb->vma, I915_VMA_RELEASE_MAP);
-		dsb->cmd_buf = NULL;
-		dsb->free_pos = 0;
-		dsb->ins_start_offset = 0;
-	}
-}
-
 /**
  * intel_dsb_indexed_reg_write() -Write to the DSB context for auto
  * increment register.
- * @dsb: intel_dsb structure.
+ * @crtc_state: intel_crtc_state structure
  * @reg: register address.
  * @val: value.
  *
@@ -189,19 +89,20 @@ void intel_dsb_put(struct intel_dsb *dsb)
  * is done through mmio write.
  */
 
-void intel_dsb_indexed_reg_write(struct intel_dsb *dsb, i915_reg_t reg,
-				 u32 val)
+void intel_dsb_indexed_reg_write(const struct intel_crtc_state *crtc_state,
+				 i915_reg_t reg, u32 val)
 {
-	struct intel_crtc *crtc = container_of(dsb, typeof(*crtc), dsb);
+	struct intel_dsb *dsb = crtc_state->dsb;
+	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
-	u32 *buf = dsb->cmd_buf;
+	u32 *buf;
 	u32 reg_val;
 
-	if (!buf) {
+	if (!dsb) {
 		intel_de_write(dev_priv, reg, val);
 		return;
 	}
-
+	buf = dsb->cmd_buf;
 	if (drm_WARN_ON(&dev_priv->drm, dsb->free_pos >= DSB_BUF_SIZE)) {
 		drm_dbg_kms(&dev_priv->drm, "DSB buffer overflow\n");
 		return;
@@ -256,7 +157,7 @@ void intel_dsb_indexed_reg_write(struct intel_dsb *dsb, i915_reg_t reg,
 /**
  * intel_dsb_reg_write() -Write to the DSB context for normal
  * register.
- * @dsb: intel_dsb structure.
+ * @crtc_state: intel_crtc_state structure
  * @reg: register address.
  * @val: value.
  *
@@ -265,17 +166,19 @@ void intel_dsb_indexed_reg_write(struct intel_dsb *dsb, i915_reg_t reg,
  * and rest all erroneous condition register programming is done
  * through mmio write.
  */
-void intel_dsb_reg_write(struct intel_dsb *dsb, i915_reg_t reg, u32 val)
+void intel_dsb_reg_write(const struct intel_crtc_state *crtc_state,
+			 i915_reg_t reg, u32 val)
 {
-	struct intel_crtc *crtc = container_of(dsb, typeof(*crtc), dsb);
+	struct intel_dsb *dsb = crtc_state->dsb;
+	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
 	u32 *buf = dsb->cmd_buf;
 
-	if (!buf) {
+	if (!dsb) {
 		intel_de_write(dev_priv, reg, val);
 		return;
 	}
-
+	buf = dsb->cmd_buf;
 	if (drm_WARN_ON(&dev_priv->drm, dsb->free_pos >= DSB_BUF_SIZE)) {
 		drm_dbg_kms(&dev_priv->drm, "DSB buffer overflow\n");
 		return;
@@ -290,26 +193,27 @@ void intel_dsb_reg_write(struct intel_dsb *dsb, i915_reg_t reg, u32 val)
 
 /**
  * intel_dsb_commit() - Trigger workload execution of DSB.
- * @dsb: intel_dsb structure.
+ * @crtc_state: intel_crtc_state structure
  *
  * This function is used to do actual write to hardware using DSB.
  * On errors, fall back to MMIO. Also this function help to reset the context.
  */
-void intel_dsb_commit(struct intel_dsb *dsb)
+void intel_dsb_commit(const struct intel_crtc_state *crtc_state)
 {
-	struct intel_crtc *crtc = container_of(dsb, typeof(*crtc), dsb);
+	struct intel_dsb *dsb = crtc_state->dsb;
+	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
 	struct drm_device *dev = crtc->base.dev;
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	enum pipe pipe = crtc->pipe;
 	u32 tail;
 
-	if (!dsb->free_pos)
+	if (!(dsb && dsb->free_pos))
 		return;
 
-	if (!intel_dsb_enable_engine(dsb))
+	if (!intel_dsb_enable_engine(dev_priv, pipe, dsb->id))
 		goto reset;
 
-	if (is_dsb_busy(dsb)) {
+	if (is_dsb_busy(dev_priv, pipe, dsb->id)) {
 		drm_err(&dev_priv->drm,
 			"HEAD_PTR write failed - dsb engine is busy.\n");
 		goto reset;
@@ -322,7 +226,7 @@ void intel_dsb_commit(struct intel_dsb *dsb)
 		memset(&dsb->cmd_buf[dsb->free_pos], 0,
 		       (tail - dsb->free_pos * 4));
 
-	if (is_dsb_busy(dsb)) {
+	if (is_dsb_busy(dev_priv, pipe, dsb->id)) {
 		drm_err(&dev_priv->drm,
 			"TAIL_PTR write failed - dsb engine is busy.\n");
 		goto reset;
@@ -332,7 +236,7 @@ void intel_dsb_commit(struct intel_dsb *dsb)
 		    i915_ggtt_offset(dsb->vma), tail);
 	intel_de_write(dev_priv, DSB_TAIL(pipe, dsb->id),
 		       i915_ggtt_offset(dsb->vma) + tail);
-	if (wait_for(!is_dsb_busy(dsb), 1)) {
+	if (wait_for(!is_dsb_busy(dev_priv, pipe, dsb->id), 1)) {
 		drm_err(&dev_priv->drm,
 			"Timed out waiting for DSB workload completion.\n");
 		goto reset;
@@ -341,5 +245,79 @@ void intel_dsb_commit(struct intel_dsb *dsb)
 reset:
 	dsb->free_pos = 0;
 	dsb->ins_start_offset = 0;
-	intel_dsb_disable_engine(dsb);
+	intel_dsb_disable_engine(dev_priv, pipe, dsb->id);
+}
+
+/**
+ * intel_dsb_prepare() - Allocate, pin and map the DSB command buffer.
+ * @crtc_state: intel_crtc_state structure to prepare associated dsb instance.
+ *
+ * This function prepare the command buffer which is used to store dsb
+ * instructions with data.
+ */
+void intel_dsb_prepare(struct intel_crtc_state *crtc_state)
+{
+	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
+	struct drm_i915_private *i915 = to_i915(crtc->base.dev);
+	struct intel_dsb *dsb;
+	struct drm_i915_gem_object *obj;
+	struct i915_vma *vma;
+	u32 *buf;
+	intel_wakeref_t wakeref;
+
+	if (!HAS_DSB(i915))
+		return;
+
+	dsb = kmalloc(sizeof(*dsb), GFP_KERNEL);
+
+	wakeref = intel_runtime_pm_get(&i915->runtime_pm);
+
+	obj = i915_gem_object_create_internal(i915, DSB_BUF_SIZE);
+	if (IS_ERR(obj)) {
+		drm_err(&i915->drm, "Gem object creation failed\n");
+		kfree(dsb);
+		goto out;
+	}
+
+	vma = i915_gem_object_ggtt_pin(obj, NULL, 0, 0, 0);
+	if (IS_ERR(vma)) {
+		drm_err(&i915->drm, "Vma creation failed\n");
+		i915_gem_object_put(obj);
+		kfree(dsb);
+		goto out;
+	}
+
+	buf = i915_gem_object_pin_map(vma->obj, I915_MAP_WC);
+	if (IS_ERR(buf)) {
+		drm_err(&i915->drm, "Command buffer creation failed\n");
+		i915_vma_unpin_and_release(&vma, I915_VMA_RELEASE_MAP);
+		kfree(dsb);
+		goto out;
+	}
+
+	dsb->id = DSB1;
+	dsb->vma = vma;
+	dsb->cmd_buf = buf;
+	dsb->free_pos = 0;
+	dsb->ins_start_offset = 0;
+	crtc_state->dsb = dsb;
+out:
+	intel_runtime_pm_put(&i915->runtime_pm, wakeref);
+}
+
+/**
+ * intel_dsb_cleanup() - To cleanup DSB context.
+ * @crtc_state: intel_crtc_state structure to cleanup associated dsb instance.
+ *
+ * This function cleanup the DSB context by unpinning and releasing
+ * the VMA object associated with it.
+ */
+void intel_dsb_cleanup(struct intel_crtc_state *crtc_state)
+{
+	if (!crtc_state->dsb)
+		return;
+
+	i915_vma_unpin_and_release(&crtc_state->dsb->vma, I915_VMA_RELEASE_MAP);
+	kfree(crtc_state->dsb);
+	crtc_state->dsb = NULL;
 }

drivers/gpu/drm/i915/display/intel_dsb.h

@@ -10,7 +10,7 @@
 
 #include "i915_reg.h"
 
-struct intel_crtc;
+struct intel_crtc_state;
 struct i915_vma;
 
 enum dsb_id {
@@ -22,7 +22,6 @@ enum dsb_id {
 };
 
 struct intel_dsb {
-	long refcount;
 	enum dsb_id id;
 	u32 *cmd_buf;
 	struct i915_vma *vma;
@@ -41,12 +40,12 @@ struct intel_dsb {
 	u32 ins_start_offset;
 };
 
-struct intel_dsb *
-intel_dsb_get(struct intel_crtc *crtc);
-void intel_dsb_put(struct intel_dsb *dsb);
-void intel_dsb_reg_write(struct intel_dsb *dsb, i915_reg_t reg, u32 val);
-void intel_dsb_indexed_reg_write(struct intel_dsb *dsb, i915_reg_t reg,
-				 u32 val);
-void intel_dsb_commit(struct intel_dsb *dsb);
+void intel_dsb_prepare(struct intel_crtc_state *crtc_state);
+void intel_dsb_cleanup(struct intel_crtc_state *crtc_state);
+void intel_dsb_reg_write(const struct intel_crtc_state *crtc_state,
+			 i915_reg_t reg, u32 val);
+void intel_dsb_indexed_reg_write(const struct intel_crtc_state *crtc_state,
+				 i915_reg_t reg, u32 val);
+void intel_dsb_commit(const struct intel_crtc_state *crtc_state);
 
 #endif