1 /* 2 * Copyright © 2014 Intel Corporation 3 * 4 * Permission is hereby granted, free of charge, to any person obtaining a 5 * copy of this software and associated documentation files (the "Software"), 6 * to deal in the Software without restriction, including without limitation 7 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 8 * and/or sell copies of the Software, and to permit persons to whom the 9 * Software is furnished to do so, subject to the following conditions: 10 * 11 * The above copyright notice and this permission notice (including the next 12 * paragraph) shall be included in all copies or substantial portions of the 13 * Software. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 21 * DEALINGS IN THE SOFTWARE. 22 * 23 * Authors: 24 * Daniel Vetter <daniel.vetter@ffwll.ch> 25 */ 26 27 /** 28 * DOC: frontbuffer tracking 29 * 30 * Many features require us to track changes to the currently active 31 * frontbuffer, especially rendering targeted at the frontbuffer. 32 * 33 * To be able to do so we track frontbuffers using a bitmask for all possible 34 * frontbuffer slots through intel_frontbuffer_track(). The functions in this 35 * file are then called when the contents of the frontbuffer are invalidated, 36 * when frontbuffer rendering has stopped again to flush out all the changes 37 * and when the frontbuffer is exchanged with a flip. Subsystems interested in 38 * frontbuffer changes (e.g. PSR, FBC, DRRS) should directly put their callbacks 39 * into the relevant places and filter for the frontbuffer slots that they are 40 * interested int. 41 * 42 * On a high level there are two types of powersaving features. The first one 43 * work like a special cache (FBC and PSR) and are interested when they should 44 * stop caching and when to restart caching. This is done by placing callbacks 45 * into the invalidate and the flush functions: At invalidate the caching must 46 * be stopped and at flush time it can be restarted. And maybe they need to know 47 * when the frontbuffer changes (e.g. when the hw doesn't initiate an invalidate 48 * and flush on its own) which can be achieved with placing callbacks into the 49 * flip functions. 50 * 51 * The other type of display power saving feature only cares about busyness 52 * (e.g. DRRS). In that case all three (invalidate, flush and flip) indicate 53 * busyness. There is no direct way to detect idleness. Instead an idle timer 54 * work delayed work should be started from the flush and flip functions and 55 * cancelled as soon as busyness is detected. 56 */ 57 58 #include "i915_drv.h" 59 #include "intel_display_trace.h" 60 #include "intel_display_types.h" 61 #include "intel_dp.h" 62 #include "intel_drrs.h" 63 #include "intel_fbc.h" 64 #include "intel_frontbuffer.h" 65 #include "intel_psr.h" 66 67 /** 68 * frontbuffer_flush - flush frontbuffer 69 * @i915: i915 device 70 * @frontbuffer_bits: frontbuffer plane tracking bits 71 * @origin: which operation caused the flush 72 * 73 * This function gets called every time rendering on the given planes has 74 * completed and frontbuffer caching can be started again. Flushes will get 75 * delayed if they're blocked by some outstanding asynchronous rendering. 76 * 77 * Can be called without any locks held. 78 */ 79 static void frontbuffer_flush(struct drm_i915_private *i915, 80 unsigned int frontbuffer_bits, 81 enum fb_op_origin origin) 82 { 83 /* Delay flushing when rings are still busy.*/ 84 spin_lock(&i915->display.fb_tracking.lock); 85 frontbuffer_bits &= ~i915->display.fb_tracking.busy_bits; 86 spin_unlock(&i915->display.fb_tracking.lock); 87 88 if (!frontbuffer_bits) 89 return; 90 91 trace_intel_frontbuffer_flush(i915, frontbuffer_bits, origin); 92 93 might_sleep(); 94 intel_drrs_flush(i915, frontbuffer_bits); 95 intel_psr_flush(i915, frontbuffer_bits, origin); 96 intel_fbc_flush(i915, frontbuffer_bits, origin); 97 } 98 99 /** 100 * intel_frontbuffer_flip_prepare - prepare asynchronous frontbuffer flip 101 * @i915: i915 device 102 * @frontbuffer_bits: frontbuffer plane tracking bits 103 * 104 * This function gets called after scheduling a flip on @obj. The actual 105 * frontbuffer flushing will be delayed until completion is signalled with 106 * intel_frontbuffer_flip_complete. If an invalidate happens in between this 107 * flush will be cancelled. 108 * 109 * Can be called without any locks held. 110 */ 111 void intel_frontbuffer_flip_prepare(struct drm_i915_private *i915, 112 unsigned frontbuffer_bits) 113 { 114 spin_lock(&i915->display.fb_tracking.lock); 115 i915->display.fb_tracking.flip_bits |= frontbuffer_bits; 116 /* Remove stale busy bits due to the old buffer. */ 117 i915->display.fb_tracking.busy_bits &= ~frontbuffer_bits; 118 spin_unlock(&i915->display.fb_tracking.lock); 119 } 120 121 /** 122 * intel_frontbuffer_flip_complete - complete asynchronous frontbuffer flip 123 * @i915: i915 device 124 * @frontbuffer_bits: frontbuffer plane tracking bits 125 * 126 * This function gets called after the flip has been latched and will complete 127 * on the next vblank. It will execute the flush if it hasn't been cancelled yet. 128 * 129 * Can be called without any locks held. 130 */ 131 void intel_frontbuffer_flip_complete(struct drm_i915_private *i915, 132 unsigned frontbuffer_bits) 133 { 134 spin_lock(&i915->display.fb_tracking.lock); 135 /* Mask any cancelled flips. */ 136 frontbuffer_bits &= i915->display.fb_tracking.flip_bits; 137 i915->display.fb_tracking.flip_bits &= ~frontbuffer_bits; 138 spin_unlock(&i915->display.fb_tracking.lock); 139 140 if (frontbuffer_bits) 141 frontbuffer_flush(i915, frontbuffer_bits, ORIGIN_FLIP); 142 } 143 144 /** 145 * intel_frontbuffer_flip - synchronous frontbuffer flip 146 * @i915: i915 device 147 * @frontbuffer_bits: frontbuffer plane tracking bits 148 * 149 * This function gets called after scheduling a flip on @obj. This is for 150 * synchronous plane updates which will happen on the next vblank and which will 151 * not get delayed by pending gpu rendering. 152 * 153 * Can be called without any locks held. 154 */ 155 void intel_frontbuffer_flip(struct drm_i915_private *i915, 156 unsigned frontbuffer_bits) 157 { 158 spin_lock(&i915->display.fb_tracking.lock); 159 /* Remove stale busy bits due to the old buffer. */ 160 i915->display.fb_tracking.busy_bits &= ~frontbuffer_bits; 161 spin_unlock(&i915->display.fb_tracking.lock); 162 163 frontbuffer_flush(i915, frontbuffer_bits, ORIGIN_FLIP); 164 } 165 166 void __intel_fb_invalidate(struct intel_frontbuffer *front, 167 enum fb_op_origin origin, 168 unsigned int frontbuffer_bits) 169 { 170 struct drm_i915_private *i915 = to_i915(front->obj->base.dev); 171 172 if (origin == ORIGIN_CS) { 173 spin_lock(&i915->display.fb_tracking.lock); 174 i915->display.fb_tracking.busy_bits |= frontbuffer_bits; 175 i915->display.fb_tracking.flip_bits &= ~frontbuffer_bits; 176 spin_unlock(&i915->display.fb_tracking.lock); 177 } 178 179 trace_intel_frontbuffer_invalidate(i915, frontbuffer_bits, origin); 180 181 might_sleep(); 182 intel_psr_invalidate(i915, frontbuffer_bits, origin); 183 intel_drrs_invalidate(i915, frontbuffer_bits); 184 intel_fbc_invalidate(i915, frontbuffer_bits, origin); 185 } 186 187 void __intel_fb_flush(struct intel_frontbuffer *front, 188 enum fb_op_origin origin, 189 unsigned int frontbuffer_bits) 190 { 191 struct drm_i915_private *i915 = to_i915(front->obj->base.dev); 192 193 if (origin == ORIGIN_CS) { 194 spin_lock(&i915->display.fb_tracking.lock); 195 /* Filter out new bits since rendering started. */ 196 frontbuffer_bits &= i915->display.fb_tracking.busy_bits; 197 i915->display.fb_tracking.busy_bits &= ~frontbuffer_bits; 198 spin_unlock(&i915->display.fb_tracking.lock); 199 } 200 201 if (frontbuffer_bits) 202 frontbuffer_flush(i915, frontbuffer_bits, origin); 203 } 204 205 static int frontbuffer_active(struct i915_active *ref) 206 { 207 struct intel_frontbuffer *front = 208 container_of(ref, typeof(*front), write); 209 210 kref_get(&front->ref); 211 return 0; 212 } 213 214 static void frontbuffer_retire(struct i915_active *ref) 215 { 216 struct intel_frontbuffer *front = 217 container_of(ref, typeof(*front), write); 218 219 intel_frontbuffer_flush(front, ORIGIN_CS); 220 intel_frontbuffer_put(front); 221 } 222 223 static void frontbuffer_release(struct kref *ref) 224 __releases(&to_i915(front->obj->base.dev)->display.fb_tracking.lock) 225 { 226 struct intel_frontbuffer *front = 227 container_of(ref, typeof(*front), ref); 228 struct drm_i915_gem_object *obj = front->obj; 229 struct i915_vma *vma; 230 231 drm_WARN_ON(obj->base.dev, atomic_read(&front->bits)); 232 233 spin_lock(&obj->vma.lock); 234 for_each_ggtt_vma(vma, obj) { 235 i915_vma_clear_scanout(vma); 236 vma->display_alignment = I915_GTT_MIN_ALIGNMENT; 237 } 238 spin_unlock(&obj->vma.lock); 239 240 RCU_INIT_POINTER(obj->frontbuffer, NULL); 241 spin_unlock(&to_i915(obj->base.dev)->display.fb_tracking.lock); 242 243 i915_active_fini(&front->write); 244 245 i915_gem_object_put(obj); 246 kfree_rcu(front, rcu); 247 } 248 249 struct intel_frontbuffer * 250 intel_frontbuffer_get(struct drm_i915_gem_object *obj) 251 { 252 struct drm_i915_private *i915 = to_i915(obj->base.dev); 253 struct intel_frontbuffer *front; 254 255 front = __intel_frontbuffer_get(obj); 256 if (front) 257 return front; 258 259 front = kmalloc(sizeof(*front), GFP_KERNEL); 260 if (!front) 261 return NULL; 262 263 front->obj = obj; 264 kref_init(&front->ref); 265 atomic_set(&front->bits, 0); 266 i915_active_init(&front->write, 267 frontbuffer_active, 268 frontbuffer_retire, 269 I915_ACTIVE_RETIRE_SLEEPS); 270 271 spin_lock(&i915->display.fb_tracking.lock); 272 if (rcu_access_pointer(obj->frontbuffer)) { 273 kfree(front); 274 front = rcu_dereference_protected(obj->frontbuffer, true); 275 kref_get(&front->ref); 276 } else { 277 i915_gem_object_get(obj); 278 rcu_assign_pointer(obj->frontbuffer, front); 279 } 280 spin_unlock(&i915->display.fb_tracking.lock); 281 282 return front; 283 } 284 285 void intel_frontbuffer_put(struct intel_frontbuffer *front) 286 { 287 kref_put_lock(&front->ref, 288 frontbuffer_release, 289 &to_i915(front->obj->base.dev)->display.fb_tracking.lock); 290 } 291 292 /** 293 * intel_frontbuffer_track - update frontbuffer tracking 294 * @old: current buffer for the frontbuffer slots 295 * @new: new buffer for the frontbuffer slots 296 * @frontbuffer_bits: bitmask of frontbuffer slots 297 * 298 * This updates the frontbuffer tracking bits @frontbuffer_bits by clearing them 299 * from @old and setting them in @new. Both @old and @new can be NULL. 300 */ 301 void intel_frontbuffer_track(struct intel_frontbuffer *old, 302 struct intel_frontbuffer *new, 303 unsigned int frontbuffer_bits) 304 { 305 /* 306 * Control of individual bits within the mask are guarded by 307 * the owning plane->mutex, i.e. we can never see concurrent 308 * manipulation of individual bits. But since the bitfield as a whole 309 * is updated using RMW, we need to use atomics in order to update 310 * the bits. 311 */ 312 BUILD_BUG_ON(INTEL_FRONTBUFFER_BITS_PER_PIPE * I915_MAX_PIPES > 313 BITS_PER_TYPE(atomic_t)); 314 BUILD_BUG_ON(INTEL_FRONTBUFFER_BITS_PER_PIPE * I915_MAX_PIPES > 32); 315 BUILD_BUG_ON(I915_MAX_PLANES > INTEL_FRONTBUFFER_BITS_PER_PIPE); 316 317 if (old) { 318 drm_WARN_ON(old->obj->base.dev, 319 !(atomic_read(&old->bits) & frontbuffer_bits)); 320 atomic_andnot(frontbuffer_bits, &old->bits); 321 } 322 323 if (new) { 324 drm_WARN_ON(new->obj->base.dev, 325 atomic_read(&new->bits) & frontbuffer_bits); 326 atomic_or(frontbuffer_bits, &new->bits); 327 } 328 } 329