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 "display/intel_dp.h" 59 60 #include "i915_drv.h" 61 #include "i915_trace.h" 62 #include "intel_display_types.h" 63 #include "intel_fbc.h" 64 #include "intel_frontbuffer.h" 65 #include "intel_drrs.h" 66 #include "intel_psr.h" 67 68 /** 69 * frontbuffer_flush - flush frontbuffer 70 * @i915: i915 device 71 * @frontbuffer_bits: frontbuffer plane tracking bits 72 * @origin: which operation caused the flush 73 * 74 * This function gets called every time rendering on the given planes has 75 * completed and frontbuffer caching can be started again. Flushes will get 76 * delayed if they're blocked by some outstanding asynchronous rendering. 77 * 78 * Can be called without any locks held. 79 */ 80 static void frontbuffer_flush(struct drm_i915_private *i915, 81 unsigned int frontbuffer_bits, 82 enum fb_op_origin origin) 83 { 84 /* Delay flushing when rings are still busy.*/ 85 spin_lock(&i915->fb_tracking.lock); 86 frontbuffer_bits &= ~i915->fb_tracking.busy_bits; 87 spin_unlock(&i915->fb_tracking.lock); 88 89 if (!frontbuffer_bits) 90 return; 91 92 trace_intel_frontbuffer_flush(frontbuffer_bits, origin); 93 94 might_sleep(); 95 intel_drrs_flush(i915, frontbuffer_bits); 96 intel_psr_flush(i915, frontbuffer_bits, origin); 97 intel_fbc_flush(i915, frontbuffer_bits, origin); 98 } 99 100 /** 101 * intel_frontbuffer_flip_prepare - prepare asynchronous frontbuffer flip 102 * @i915: i915 device 103 * @frontbuffer_bits: frontbuffer plane tracking bits 104 * 105 * This function gets called after scheduling a flip on @obj. The actual 106 * frontbuffer flushing will be delayed until completion is signalled with 107 * intel_frontbuffer_flip_complete. If an invalidate happens in between this 108 * flush will be cancelled. 109 * 110 * Can be called without any locks held. 111 */ 112 void intel_frontbuffer_flip_prepare(struct drm_i915_private *i915, 113 unsigned frontbuffer_bits) 114 { 115 spin_lock(&i915->fb_tracking.lock); 116 i915->fb_tracking.flip_bits |= frontbuffer_bits; 117 /* Remove stale busy bits due to the old buffer. */ 118 i915->fb_tracking.busy_bits &= ~frontbuffer_bits; 119 spin_unlock(&i915->fb_tracking.lock); 120 } 121 122 /** 123 * intel_frontbuffer_flip_complete - complete asynchronous frontbuffer flip 124 * @i915: i915 device 125 * @frontbuffer_bits: frontbuffer plane tracking bits 126 * 127 * This function gets called after the flip has been latched and will complete 128 * on the next vblank. It will execute the flush if it hasn't been cancelled yet. 129 * 130 * Can be called without any locks held. 131 */ 132 void intel_frontbuffer_flip_complete(struct drm_i915_private *i915, 133 unsigned frontbuffer_bits) 134 { 135 spin_lock(&i915->fb_tracking.lock); 136 /* Mask any cancelled flips. */ 137 frontbuffer_bits &= i915->fb_tracking.flip_bits; 138 i915->fb_tracking.flip_bits &= ~frontbuffer_bits; 139 spin_unlock(&i915->fb_tracking.lock); 140 141 if (frontbuffer_bits) 142 frontbuffer_flush(i915, frontbuffer_bits, ORIGIN_FLIP); 143 } 144 145 /** 146 * intel_frontbuffer_flip - synchronous frontbuffer flip 147 * @i915: i915 device 148 * @frontbuffer_bits: frontbuffer plane tracking bits 149 * 150 * This function gets called after scheduling a flip on @obj. This is for 151 * synchronous plane updates which will happen on the next vblank and which will 152 * not get delayed by pending gpu rendering. 153 * 154 * Can be called without any locks held. 155 */ 156 void intel_frontbuffer_flip(struct drm_i915_private *i915, 157 unsigned frontbuffer_bits) 158 { 159 spin_lock(&i915->fb_tracking.lock); 160 /* Remove stale busy bits due to the old buffer. */ 161 i915->fb_tracking.busy_bits &= ~frontbuffer_bits; 162 spin_unlock(&i915->fb_tracking.lock); 163 164 frontbuffer_flush(i915, frontbuffer_bits, ORIGIN_FLIP); 165 } 166 167 void __intel_fb_invalidate(struct intel_frontbuffer *front, 168 enum fb_op_origin origin, 169 unsigned int frontbuffer_bits) 170 { 171 struct drm_i915_private *i915 = to_i915(front->obj->base.dev); 172 173 if (origin == ORIGIN_CS) { 174 spin_lock(&i915->fb_tracking.lock); 175 i915->fb_tracking.busy_bits |= frontbuffer_bits; 176 i915->fb_tracking.flip_bits &= ~frontbuffer_bits; 177 spin_unlock(&i915->fb_tracking.lock); 178 } 179 180 trace_intel_frontbuffer_invalidate(frontbuffer_bits, origin); 181 182 might_sleep(); 183 intel_psr_invalidate(i915, frontbuffer_bits, origin); 184 intel_drrs_invalidate(i915, frontbuffer_bits); 185 intel_fbc_invalidate(i915, frontbuffer_bits, origin); 186 } 187 188 void __intel_fb_flush(struct intel_frontbuffer *front, 189 enum fb_op_origin origin, 190 unsigned int frontbuffer_bits) 191 { 192 struct drm_i915_private *i915 = to_i915(front->obj->base.dev); 193 194 if (origin == ORIGIN_CS) { 195 spin_lock(&i915->fb_tracking.lock); 196 /* Filter out new bits since rendering started. */ 197 frontbuffer_bits &= i915->fb_tracking.busy_bits; 198 i915->fb_tracking.busy_bits &= ~frontbuffer_bits; 199 spin_unlock(&i915->fb_tracking.lock); 200 } 201 202 if (frontbuffer_bits) 203 frontbuffer_flush(i915, frontbuffer_bits, origin); 204 } 205 206 static int frontbuffer_active(struct i915_active *ref) 207 { 208 struct intel_frontbuffer *front = 209 container_of(ref, typeof(*front), write); 210 211 kref_get(&front->ref); 212 return 0; 213 } 214 215 static void frontbuffer_retire(struct i915_active *ref) 216 { 217 struct intel_frontbuffer *front = 218 container_of(ref, typeof(*front), write); 219 220 intel_frontbuffer_flush(front, ORIGIN_CS); 221 intel_frontbuffer_put(front); 222 } 223 224 static void frontbuffer_release(struct kref *ref) 225 __releases(&to_i915(front->obj->base.dev)->fb_tracking.lock) 226 { 227 struct intel_frontbuffer *front = 228 container_of(ref, typeof(*front), ref); 229 struct drm_i915_gem_object *obj = front->obj; 230 struct i915_vma *vma; 231 232 drm_WARN_ON(obj->base.dev, atomic_read(&front->bits)); 233 234 spin_lock(&obj->vma.lock); 235 for_each_ggtt_vma(vma, obj) { 236 i915_vma_clear_scanout(vma); 237 vma->display_alignment = I915_GTT_MIN_ALIGNMENT; 238 } 239 spin_unlock(&obj->vma.lock); 240 241 RCU_INIT_POINTER(obj->frontbuffer, NULL); 242 spin_unlock(&to_i915(obj->base.dev)->fb_tracking.lock); 243 244 i915_active_fini(&front->write); 245 246 i915_gem_object_put(obj); 247 kfree_rcu(front, rcu); 248 } 249 250 struct intel_frontbuffer * 251 intel_frontbuffer_get(struct drm_i915_gem_object *obj) 252 { 253 struct drm_i915_private *i915 = to_i915(obj->base.dev); 254 struct intel_frontbuffer *front; 255 256 front = __intel_frontbuffer_get(obj); 257 if (front) 258 return front; 259 260 front = kmalloc(sizeof(*front), GFP_KERNEL); 261 if (!front) 262 return NULL; 263 264 front->obj = obj; 265 kref_init(&front->ref); 266 atomic_set(&front->bits, 0); 267 i915_active_init(&front->write, 268 frontbuffer_active, 269 frontbuffer_retire, 270 I915_ACTIVE_RETIRE_SLEEPS); 271 272 spin_lock(&i915->fb_tracking.lock); 273 if (rcu_access_pointer(obj->frontbuffer)) { 274 kfree(front); 275 front = rcu_dereference_protected(obj->frontbuffer, true); 276 kref_get(&front->ref); 277 } else { 278 i915_gem_object_get(obj); 279 rcu_assign_pointer(obj->frontbuffer, front); 280 } 281 spin_unlock(&i915->fb_tracking.lock); 282 283 return front; 284 } 285 286 void intel_frontbuffer_put(struct intel_frontbuffer *front) 287 { 288 kref_put_lock(&front->ref, 289 frontbuffer_release, 290 &to_i915(front->obj->base.dev)->fb_tracking.lock); 291 } 292 293 /** 294 * intel_frontbuffer_track - update frontbuffer tracking 295 * @old: current buffer for the frontbuffer slots 296 * @new: new buffer for the frontbuffer slots 297 * @frontbuffer_bits: bitmask of frontbuffer slots 298 * 299 * This updates the frontbuffer tracking bits @frontbuffer_bits by clearing them 300 * from @old and setting them in @new. Both @old and @new can be NULL. 301 */ 302 void intel_frontbuffer_track(struct intel_frontbuffer *old, 303 struct intel_frontbuffer *new, 304 unsigned int frontbuffer_bits) 305 { 306 /* 307 * Control of individual bits within the mask are guarded by 308 * the owning plane->mutex, i.e. we can never see concurrent 309 * manipulation of individual bits. But since the bitfield as a whole 310 * is updated using RMW, we need to use atomics in order to update 311 * the bits. 312 */ 313 BUILD_BUG_ON(INTEL_FRONTBUFFER_BITS_PER_PIPE * I915_MAX_PIPES > 314 BITS_PER_TYPE(atomic_t)); 315 316 if (old) { 317 drm_WARN_ON(old->obj->base.dev, 318 !(atomic_read(&old->bits) & frontbuffer_bits)); 319 atomic_andnot(frontbuffer_bits, &old->bits); 320 } 321 322 if (new) { 323 drm_WARN_ON(new->obj->base.dev, 324 atomic_read(&new->bits) & frontbuffer_bits); 325 atomic_or(frontbuffer_bits, &new->bits); 326 } 327 } 328