xref: /linux/drivers/gpu/drm/panfrost/panfrost_gpu.c (revision 7f71507851fc7764b36a3221839607d3a45c2025)
1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright 2018 Marty E. Plummer <hanetzer@startmail.com> */
3 /* Copyright 2019 Linaro, Ltd., Rob Herring <robh@kernel.org> */
4 /* Copyright 2019 Collabora ltd. */
5 #include <linux/bitfield.h>
6 #include <linux/bitmap.h>
7 #include <linux/delay.h>
8 #include <linux/dma-mapping.h>
9 #include <linux/interrupt.h>
10 #include <linux/io.h>
11 #include <linux/iopoll.h>
12 #include <linux/platform_device.h>
13 #include <linux/pm_runtime.h>
14 
15 #include "panfrost_device.h"
16 #include "panfrost_features.h"
17 #include "panfrost_issues.h"
18 #include "panfrost_gpu.h"
19 #include "panfrost_perfcnt.h"
20 #include "panfrost_regs.h"
21 
22 static irqreturn_t panfrost_gpu_irq_handler(int irq, void *data)
23 {
24 	struct panfrost_device *pfdev = data;
25 	u32 fault_status, state;
26 
27 	if (test_bit(PANFROST_COMP_BIT_GPU, pfdev->is_suspended))
28 		return IRQ_NONE;
29 
30 	fault_status = gpu_read(pfdev, GPU_FAULT_STATUS);
31 	state = gpu_read(pfdev, GPU_INT_STAT);
32 	if (!state)
33 		return IRQ_NONE;
34 
35 	if (state & GPU_IRQ_MASK_ERROR) {
36 		u64 address = (u64) gpu_read(pfdev, GPU_FAULT_ADDRESS_HI) << 32;
37 		address |= gpu_read(pfdev, GPU_FAULT_ADDRESS_LO);
38 
39 		dev_warn(pfdev->dev, "GPU Fault 0x%08x (%s) at 0x%016llx\n",
40 			 fault_status, panfrost_exception_name(fault_status & 0xFF),
41 			 address);
42 
43 		if (state & GPU_IRQ_MULTIPLE_FAULT)
44 			dev_warn(pfdev->dev, "There were multiple GPU faults - some have not been reported\n");
45 
46 		gpu_write(pfdev, GPU_INT_MASK, 0);
47 	}
48 
49 	if (state & GPU_IRQ_PERFCNT_SAMPLE_COMPLETED)
50 		panfrost_perfcnt_sample_done(pfdev);
51 
52 	if (state & GPU_IRQ_CLEAN_CACHES_COMPLETED)
53 		panfrost_perfcnt_clean_cache_done(pfdev);
54 
55 	gpu_write(pfdev, GPU_INT_CLEAR, state);
56 
57 	return IRQ_HANDLED;
58 }
59 
60 int panfrost_gpu_soft_reset(struct panfrost_device *pfdev)
61 {
62 	int ret;
63 	u32 val;
64 
65 	gpu_write(pfdev, GPU_INT_MASK, 0);
66 	gpu_write(pfdev, GPU_INT_CLEAR, GPU_IRQ_RESET_COMPLETED);
67 
68 	clear_bit(PANFROST_COMP_BIT_GPU, pfdev->is_suspended);
69 
70 	gpu_write(pfdev, GPU_CMD, GPU_CMD_SOFT_RESET);
71 	ret = readl_relaxed_poll_timeout(pfdev->iomem + GPU_INT_RAWSTAT,
72 		val, val & GPU_IRQ_RESET_COMPLETED, 10, 10000);
73 
74 	if (ret) {
75 		dev_err(pfdev->dev, "gpu soft reset timed out, attempting hard reset\n");
76 
77 		gpu_write(pfdev, GPU_CMD, GPU_CMD_HARD_RESET);
78 		ret = readl_relaxed_poll_timeout(pfdev->iomem + GPU_INT_RAWSTAT, val,
79 						 val & GPU_IRQ_RESET_COMPLETED, 100, 10000);
80 		if (ret) {
81 			dev_err(pfdev->dev, "gpu hard reset timed out\n");
82 			return ret;
83 		}
84 	}
85 
86 	gpu_write(pfdev, GPU_INT_CLEAR, GPU_IRQ_MASK_ALL);
87 
88 	/* Only enable the interrupts we care about */
89 	gpu_write(pfdev, GPU_INT_MASK,
90 		  GPU_IRQ_MASK_ERROR |
91 		  GPU_IRQ_PERFCNT_SAMPLE_COMPLETED |
92 		  GPU_IRQ_CLEAN_CACHES_COMPLETED);
93 
94 	/*
95 	 * All in-flight jobs should have released their cycle
96 	 * counter references upon reset, but let us make sure
97 	 */
98 	if (drm_WARN_ON(pfdev->ddev, atomic_read(&pfdev->cycle_counter.use_count) != 0))
99 		atomic_set(&pfdev->cycle_counter.use_count, 0);
100 
101 	return 0;
102 }
103 
104 void panfrost_gpu_amlogic_quirk(struct panfrost_device *pfdev)
105 {
106 	/*
107 	 * The Amlogic integrated Mali-T820, Mali-G31 & Mali-G52 needs
108 	 * these undocumented bits in GPU_PWR_OVERRIDE1 to be set in order
109 	 * to operate correctly.
110 	 */
111 	gpu_write(pfdev, GPU_PWR_KEY, GPU_PWR_KEY_UNLOCK);
112 	gpu_write(pfdev, GPU_PWR_OVERRIDE1, 0xfff | (0x20 << 16));
113 }
114 
115 static void panfrost_gpu_init_quirks(struct panfrost_device *pfdev)
116 {
117 	u32 quirks = 0;
118 
119 	if (panfrost_has_hw_issue(pfdev, HW_ISSUE_8443) ||
120 	    panfrost_has_hw_issue(pfdev, HW_ISSUE_11035))
121 		quirks |= SC_LS_PAUSEBUFFER_DISABLE;
122 
123 	if (panfrost_has_hw_issue(pfdev, HW_ISSUE_10327))
124 		quirks |= SC_SDC_DISABLE_OQ_DISCARD;
125 
126 	if (panfrost_has_hw_issue(pfdev, HW_ISSUE_10797))
127 		quirks |= SC_ENABLE_TEXGRD_FLAGS;
128 
129 	if (!panfrost_has_hw_issue(pfdev, GPUCORE_1619)) {
130 		if (panfrost_model_cmp(pfdev, 0x750) < 0) /* T60x, T62x, T72x */
131 			quirks |= SC_LS_ATTR_CHECK_DISABLE;
132 		else if (panfrost_model_cmp(pfdev, 0x880) <= 0) /* T76x, T8xx */
133 			quirks |= SC_LS_ALLOW_ATTR_TYPES;
134 	}
135 
136 	if (panfrost_has_hw_issue(pfdev, HW_ISSUE_TTRX_2968_TTRX_3162))
137 		quirks |= SC_VAR_ALGORITHM;
138 
139 	if (panfrost_has_hw_feature(pfdev, HW_FEATURE_TLS_HASHING))
140 		quirks |= SC_TLS_HASH_ENABLE;
141 
142 	if (quirks)
143 		gpu_write(pfdev, GPU_SHADER_CONFIG, quirks);
144 
145 
146 	quirks = gpu_read(pfdev, GPU_TILER_CONFIG);
147 
148 	/* Set tiler clock gate override if required */
149 	if (panfrost_has_hw_issue(pfdev, HW_ISSUE_T76X_3953))
150 		quirks |= TC_CLOCK_GATE_OVERRIDE;
151 
152 	gpu_write(pfdev, GPU_TILER_CONFIG, quirks);
153 
154 
155 	quirks = 0;
156 	if ((panfrost_model_eq(pfdev, 0x860) || panfrost_model_eq(pfdev, 0x880)) &&
157 	    pfdev->features.revision >= 0x2000)
158 		quirks |= JM_MAX_JOB_THROTTLE_LIMIT << JM_JOB_THROTTLE_LIMIT_SHIFT;
159 	else if (panfrost_model_eq(pfdev, 0x6000) &&
160 		 pfdev->features.coherency_features == COHERENCY_ACE)
161 		quirks |= (COHERENCY_ACE_LITE | COHERENCY_ACE) <<
162 			   JM_FORCE_COHERENCY_FEATURES_SHIFT;
163 
164 	if (panfrost_has_hw_feature(pfdev, HW_FEATURE_IDVS_GROUP_SIZE))
165 		quirks |= JM_DEFAULT_IDVS_GROUP_SIZE << JM_IDVS_GROUP_SIZE_SHIFT;
166 
167 	if (quirks)
168 		gpu_write(pfdev, GPU_JM_CONFIG, quirks);
169 
170 	/* Here goes platform specific quirks */
171 	if (pfdev->comp->vendor_quirk)
172 		pfdev->comp->vendor_quirk(pfdev);
173 }
174 
175 #define MAX_HW_REVS 6
176 
177 struct panfrost_model {
178 	const char *name;
179 	u32 id;
180 	u64 features;
181 	u64 issues;
182 	struct {
183 		u32 revision;
184 		u64 issues;
185 	} revs[MAX_HW_REVS];
186 };
187 
188 #define GPU_MODEL(_name, _id, ...) \
189 {\
190 	.name = __stringify(_name),				\
191 	.id = _id,						\
192 	.features = hw_features_##_name,			\
193 	.issues = hw_issues_##_name,				\
194 	.revs = { __VA_ARGS__ },				\
195 }
196 
197 #define GPU_REV_EXT(name, _rev, _p, _s, stat) \
198 {\
199 	.revision = (_rev) << 12 | (_p) << 4 | (_s),		\
200 	.issues = hw_issues_##name##_r##_rev##p##_p##stat,	\
201 }
202 #define GPU_REV(name, r, p) GPU_REV_EXT(name, r, p, 0, )
203 
204 static const struct panfrost_model gpu_models[] = {
205 	/* T60x has an oddball version */
206 	GPU_MODEL(t600, 0x600,
207 		GPU_REV_EXT(t600, 0, 0, 1, _15dev0)),
208 	GPU_MODEL(t620, 0x620,
209 		GPU_REV(t620, 0, 1), GPU_REV(t620, 1, 0)),
210 	GPU_MODEL(t720, 0x720),
211 	GPU_MODEL(t760, 0x750,
212 		GPU_REV(t760, 0, 0), GPU_REV(t760, 0, 1),
213 		GPU_REV_EXT(t760, 0, 1, 0, _50rel0),
214 		GPU_REV(t760, 0, 2), GPU_REV(t760, 0, 3)),
215 	GPU_MODEL(t820, 0x820),
216 	GPU_MODEL(t830, 0x830),
217 	GPU_MODEL(t860, 0x860),
218 	GPU_MODEL(t880, 0x880),
219 
220 	GPU_MODEL(g71, 0x6000,
221 		GPU_REV_EXT(g71, 0, 0, 1, _05dev0)),
222 	GPU_MODEL(g72, 0x6001),
223 	GPU_MODEL(g51, 0x7000),
224 	GPU_MODEL(g76, 0x7001),
225 	GPU_MODEL(g52, 0x7002),
226 	GPU_MODEL(g31, 0x7003,
227 		GPU_REV(g31, 1, 0)),
228 
229 	GPU_MODEL(g57, 0x9001,
230 		GPU_REV(g57, 0, 0)),
231 
232 	/* MediaTek MT8192 has a Mali-G57 with a different GPU ID from the
233 	 * standard. Arm's driver does not appear to handle this model.
234 	 * ChromeOS has a hack downstream for it. Treat it as equivalent to
235 	 * standard Mali-G57 for now.
236 	 */
237 	GPU_MODEL(g57, 0x9003,
238 		GPU_REV(g57, 0, 0)),
239 };
240 
241 static void panfrost_gpu_init_features(struct panfrost_device *pfdev)
242 {
243 	u32 gpu_id, num_js, major, minor, status, rev;
244 	const char *name = "unknown";
245 	u64 hw_feat = 0;
246 	u64 hw_issues = hw_issues_all;
247 	const struct panfrost_model *model;
248 	int i;
249 
250 	pfdev->features.l2_features = gpu_read(pfdev, GPU_L2_FEATURES);
251 	pfdev->features.core_features = gpu_read(pfdev, GPU_CORE_FEATURES);
252 	pfdev->features.tiler_features = gpu_read(pfdev, GPU_TILER_FEATURES);
253 	pfdev->features.mem_features = gpu_read(pfdev, GPU_MEM_FEATURES);
254 	pfdev->features.mmu_features = gpu_read(pfdev, GPU_MMU_FEATURES);
255 	pfdev->features.thread_features = gpu_read(pfdev, GPU_THREAD_FEATURES);
256 	pfdev->features.max_threads = gpu_read(pfdev, GPU_THREAD_MAX_THREADS);
257 	pfdev->features.thread_max_workgroup_sz = gpu_read(pfdev, GPU_THREAD_MAX_WORKGROUP_SIZE);
258 	pfdev->features.thread_max_barrier_sz = gpu_read(pfdev, GPU_THREAD_MAX_BARRIER_SIZE);
259 	pfdev->features.coherency_features = gpu_read(pfdev, GPU_COHERENCY_FEATURES);
260 	pfdev->features.afbc_features = gpu_read(pfdev, GPU_AFBC_FEATURES);
261 	for (i = 0; i < 4; i++)
262 		pfdev->features.texture_features[i] = gpu_read(pfdev, GPU_TEXTURE_FEATURES(i));
263 
264 	pfdev->features.as_present = gpu_read(pfdev, GPU_AS_PRESENT);
265 
266 	pfdev->features.js_present = gpu_read(pfdev, GPU_JS_PRESENT);
267 	num_js = hweight32(pfdev->features.js_present);
268 	for (i = 0; i < num_js; i++)
269 		pfdev->features.js_features[i] = gpu_read(pfdev, GPU_JS_FEATURES(i));
270 
271 	pfdev->features.shader_present = gpu_read(pfdev, GPU_SHADER_PRESENT_LO);
272 	pfdev->features.shader_present |= (u64)gpu_read(pfdev, GPU_SHADER_PRESENT_HI) << 32;
273 
274 	pfdev->features.tiler_present = gpu_read(pfdev, GPU_TILER_PRESENT_LO);
275 	pfdev->features.tiler_present |= (u64)gpu_read(pfdev, GPU_TILER_PRESENT_HI) << 32;
276 
277 	pfdev->features.l2_present = gpu_read(pfdev, GPU_L2_PRESENT_LO);
278 	pfdev->features.l2_present |= (u64)gpu_read(pfdev, GPU_L2_PRESENT_HI) << 32;
279 	pfdev->features.nr_core_groups = hweight64(pfdev->features.l2_present);
280 
281 	pfdev->features.stack_present = gpu_read(pfdev, GPU_STACK_PRESENT_LO);
282 	pfdev->features.stack_present |= (u64)gpu_read(pfdev, GPU_STACK_PRESENT_HI) << 32;
283 
284 	pfdev->features.thread_tls_alloc = gpu_read(pfdev, GPU_THREAD_TLS_ALLOC);
285 
286 	gpu_id = gpu_read(pfdev, GPU_ID);
287 	pfdev->features.revision = gpu_id & 0xffff;
288 	pfdev->features.id = gpu_id >> 16;
289 
290 	/* The T60x has an oddball ID value. Fix it up to the standard Midgard
291 	 * format so we (and userspace) don't have to special case it.
292 	 */
293 	if (pfdev->features.id == 0x6956)
294 		pfdev->features.id = 0x0600;
295 
296 	major = (pfdev->features.revision >> 12) & 0xf;
297 	minor = (pfdev->features.revision >> 4) & 0xff;
298 	status = pfdev->features.revision & 0xf;
299 	rev = pfdev->features.revision;
300 
301 	gpu_id = pfdev->features.id;
302 
303 	for (model = gpu_models; model->name; model++) {
304 		int best = -1;
305 
306 		if (!panfrost_model_eq(pfdev, model->id))
307 			continue;
308 
309 		name = model->name;
310 		hw_feat = model->features;
311 		hw_issues |= model->issues;
312 		for (i = 0; i < MAX_HW_REVS; i++) {
313 			if (model->revs[i].revision == rev) {
314 				best = i;
315 				break;
316 			} else if (model->revs[i].revision == (rev & ~0xf))
317 				best = i;
318 		}
319 
320 		if (best >= 0)
321 			hw_issues |= model->revs[best].issues;
322 
323 		break;
324 	}
325 
326 	bitmap_from_u64(pfdev->features.hw_features, hw_feat);
327 	bitmap_from_u64(pfdev->features.hw_issues, hw_issues);
328 
329 	dev_info(pfdev->dev, "mali-%s id 0x%x major 0x%x minor 0x%x status 0x%x",
330 		 name, gpu_id, major, minor, status);
331 	dev_info(pfdev->dev, "features: %64pb, issues: %64pb",
332 		 pfdev->features.hw_features,
333 		 pfdev->features.hw_issues);
334 
335 	dev_info(pfdev->dev, "Features: L2:0x%08x Shader:0x%08x Tiler:0x%08x Mem:0x%0x MMU:0x%08x AS:0x%x JS:0x%x",
336 		 pfdev->features.l2_features,
337 		 pfdev->features.core_features,
338 		 pfdev->features.tiler_features,
339 		 pfdev->features.mem_features,
340 		 pfdev->features.mmu_features,
341 		 pfdev->features.as_present,
342 		 pfdev->features.js_present);
343 
344 	dev_info(pfdev->dev, "shader_present=0x%0llx l2_present=0x%0llx",
345 		 pfdev->features.shader_present, pfdev->features.l2_present);
346 }
347 
348 void panfrost_cycle_counter_get(struct panfrost_device *pfdev)
349 {
350 	if (atomic_inc_not_zero(&pfdev->cycle_counter.use_count))
351 		return;
352 
353 	spin_lock(&pfdev->cycle_counter.lock);
354 	if (atomic_inc_return(&pfdev->cycle_counter.use_count) == 1)
355 		gpu_write(pfdev, GPU_CMD, GPU_CMD_CYCLE_COUNT_START);
356 	spin_unlock(&pfdev->cycle_counter.lock);
357 }
358 
359 void panfrost_cycle_counter_put(struct panfrost_device *pfdev)
360 {
361 	if (atomic_add_unless(&pfdev->cycle_counter.use_count, -1, 1))
362 		return;
363 
364 	spin_lock(&pfdev->cycle_counter.lock);
365 	if (atomic_dec_return(&pfdev->cycle_counter.use_count) == 0)
366 		gpu_write(pfdev, GPU_CMD, GPU_CMD_CYCLE_COUNT_STOP);
367 	spin_unlock(&pfdev->cycle_counter.lock);
368 }
369 
370 unsigned long long panfrost_cycle_counter_read(struct panfrost_device *pfdev)
371 {
372 	u32 hi, lo;
373 
374 	do {
375 		hi = gpu_read(pfdev, GPU_CYCLE_COUNT_HI);
376 		lo = gpu_read(pfdev, GPU_CYCLE_COUNT_LO);
377 	} while (hi != gpu_read(pfdev, GPU_CYCLE_COUNT_HI));
378 
379 	return ((u64)hi << 32) | lo;
380 }
381 
382 unsigned long long panfrost_timestamp_read(struct panfrost_device *pfdev)
383 {
384 	u32 hi, lo;
385 
386 	do {
387 		hi = gpu_read(pfdev, GPU_TIMESTAMP_HI);
388 		lo = gpu_read(pfdev, GPU_TIMESTAMP_LO);
389 	} while (hi != gpu_read(pfdev, GPU_TIMESTAMP_HI));
390 
391 	return ((u64)hi << 32) | lo;
392 }
393 
394 static u64 panfrost_get_core_mask(struct panfrost_device *pfdev)
395 {
396 	u64 core_mask;
397 
398 	if (pfdev->features.l2_present == 1)
399 		return U64_MAX;
400 
401 	/*
402 	 * Only support one core group now.
403 	 * ~(l2_present - 1) unsets all bits in l2_present except
404 	 * the bottom bit. (l2_present - 2) has all the bits in
405 	 * the first core group set. AND them together to generate
406 	 * a mask of cores in the first core group.
407 	 */
408 	core_mask = ~(pfdev->features.l2_present - 1) &
409 		     (pfdev->features.l2_present - 2);
410 	dev_info_once(pfdev->dev, "using only 1st core group (%lu cores from %lu)\n",
411 		      hweight64(core_mask),
412 		      hweight64(pfdev->features.shader_present));
413 
414 	return core_mask;
415 }
416 
417 void panfrost_gpu_power_on(struct panfrost_device *pfdev)
418 {
419 	int ret;
420 	u32 val;
421 	u64 core_mask;
422 
423 	panfrost_gpu_init_quirks(pfdev);
424 	core_mask = panfrost_get_core_mask(pfdev);
425 
426 	gpu_write(pfdev, L2_PWRON_LO, pfdev->features.l2_present & core_mask);
427 	ret = readl_relaxed_poll_timeout(pfdev->iomem + L2_READY_LO,
428 		val, val == (pfdev->features.l2_present & core_mask),
429 		10, 20000);
430 	if (ret)
431 		dev_err(pfdev->dev, "error powering up gpu L2");
432 
433 	gpu_write(pfdev, SHADER_PWRON_LO,
434 		  pfdev->features.shader_present & core_mask);
435 	ret = readl_relaxed_poll_timeout(pfdev->iomem + SHADER_READY_LO,
436 		val, val == (pfdev->features.shader_present & core_mask),
437 		10, 20000);
438 	if (ret)
439 		dev_err(pfdev->dev, "error powering up gpu shader");
440 
441 	gpu_write(pfdev, TILER_PWRON_LO, pfdev->features.tiler_present);
442 	ret = readl_relaxed_poll_timeout(pfdev->iomem + TILER_READY_LO,
443 		val, val == pfdev->features.tiler_present, 10, 1000);
444 	if (ret)
445 		dev_err(pfdev->dev, "error powering up gpu tiler");
446 }
447 
448 void panfrost_gpu_power_off(struct panfrost_device *pfdev)
449 {
450 	int ret;
451 	u32 val;
452 
453 	gpu_write(pfdev, SHADER_PWROFF_LO, pfdev->features.shader_present);
454 	ret = readl_relaxed_poll_timeout(pfdev->iomem + SHADER_PWRTRANS_LO,
455 					 val, !val, 1, 2000);
456 	if (ret)
457 		dev_err(pfdev->dev, "shader power transition timeout");
458 
459 	gpu_write(pfdev, TILER_PWROFF_LO, pfdev->features.tiler_present);
460 	ret = readl_relaxed_poll_timeout(pfdev->iomem + TILER_PWRTRANS_LO,
461 					 val, !val, 1, 2000);
462 	if (ret)
463 		dev_err(pfdev->dev, "tiler power transition timeout");
464 
465 	gpu_write(pfdev, L2_PWROFF_LO, pfdev->features.l2_present);
466 	ret = readl_poll_timeout(pfdev->iomem + L2_PWRTRANS_LO,
467 				 val, !val, 0, 2000);
468 	if (ret)
469 		dev_err(pfdev->dev, "l2 power transition timeout");
470 }
471 
472 void panfrost_gpu_suspend_irq(struct panfrost_device *pfdev)
473 {
474 	set_bit(PANFROST_COMP_BIT_GPU, pfdev->is_suspended);
475 
476 	gpu_write(pfdev, GPU_INT_MASK, 0);
477 	synchronize_irq(pfdev->gpu_irq);
478 }
479 
480 int panfrost_gpu_init(struct panfrost_device *pfdev)
481 {
482 	int err;
483 
484 	err = panfrost_gpu_soft_reset(pfdev);
485 	if (err)
486 		return err;
487 
488 	panfrost_gpu_init_features(pfdev);
489 
490 	err = dma_set_mask_and_coherent(pfdev->dev,
491 		DMA_BIT_MASK(FIELD_GET(0xff00, pfdev->features.mmu_features)));
492 	if (err)
493 		return err;
494 
495 	dma_set_max_seg_size(pfdev->dev, UINT_MAX);
496 
497 	pfdev->gpu_irq = platform_get_irq_byname(to_platform_device(pfdev->dev), "gpu");
498 	if (pfdev->gpu_irq < 0)
499 		return pfdev->gpu_irq;
500 
501 	err = devm_request_irq(pfdev->dev, pfdev->gpu_irq, panfrost_gpu_irq_handler,
502 			       IRQF_SHARED, KBUILD_MODNAME "-gpu", pfdev);
503 	if (err) {
504 		dev_err(pfdev->dev, "failed to request gpu irq");
505 		return err;
506 	}
507 
508 	panfrost_gpu_power_on(pfdev);
509 
510 	return 0;
511 }
512 
513 void panfrost_gpu_fini(struct panfrost_device *pfdev)
514 {
515 	panfrost_gpu_power_off(pfdev);
516 }
517 
518 u32 panfrost_gpu_get_latest_flush_id(struct panfrost_device *pfdev)
519 {
520 	u32 flush_id;
521 
522 	if (panfrost_has_hw_feature(pfdev, HW_FEATURE_FLUSH_REDUCTION)) {
523 		/* Flush reduction only makes sense when the GPU is kept powered on between jobs */
524 		if (pm_runtime_get_if_in_use(pfdev->dev)) {
525 			flush_id = gpu_read(pfdev, GPU_LATEST_FLUSH_ID);
526 			pm_runtime_put(pfdev->dev);
527 			return flush_id;
528 		}
529 	}
530 
531 	return 0;
532 }
533