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1 /*
2  * Copyright © 2013 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 DEALINGS
21  * IN THE SOFTWARE.
22  *
23  */
24 
25 #include <asm/iosf_mbi.h>
26 
27 #include "i915_drv.h"
28 #include "intel_sideband.h"
29 
30 /*
31  * IOSF sideband, see VLV2_SidebandMsg_HAS.docx and
32  * VLV_VLV2_PUNIT_HAS_0.8.docx
33  */
34 
35 /* Standard MMIO read, non-posted */
36 #define SB_MRD_NP	0x00
37 /* Standard MMIO write, non-posted */
38 #define SB_MWR_NP	0x01
39 /* Private register read, double-word addressing, non-posted */
40 #define SB_CRRDDA_NP	0x06
41 /* Private register write, double-word addressing, non-posted */
42 #define SB_CRWRDA_NP	0x07
43 
ping(void * info)44 static void ping(void *info)
45 {
46 }
47 
__vlv_punit_get(struct drm_i915_private * i915)48 static void __vlv_punit_get(struct drm_i915_private *i915)
49 {
50 	iosf_mbi_punit_acquire();
51 
52 	/*
53 	 * Prevent the cpu from sleeping while we use this sideband, otherwise
54 	 * the punit may cause a machine hang. The issue appears to be isolated
55 	 * with changing the power state of the CPU package while changing
56 	 * the power state via the punit, and we have only observed it
57 	 * reliably on 4-core Baytail systems suggesting the issue is in the
58 	 * power delivery mechanism and likely to be be board/function
59 	 * specific. Hence we presume the workaround needs only be applied
60 	 * to the Valleyview P-unit and not all sideband communications.
61 	 */
62 	if (IS_VALLEYVIEW(i915)) {
63 		cpu_latency_qos_update_request(&i915->sb_qos, 0);
64 		on_each_cpu(ping, NULL, 1);
65 	}
66 }
67 
__vlv_punit_put(struct drm_i915_private * i915)68 static void __vlv_punit_put(struct drm_i915_private *i915)
69 {
70 	if (IS_VALLEYVIEW(i915))
71 		cpu_latency_qos_update_request(&i915->sb_qos,
72 					       PM_QOS_DEFAULT_VALUE);
73 
74 	iosf_mbi_punit_release();
75 }
76 
vlv_iosf_sb_get(struct drm_i915_private * i915,unsigned long ports)77 void vlv_iosf_sb_get(struct drm_i915_private *i915, unsigned long ports)
78 {
79 	if (ports & BIT(VLV_IOSF_SB_PUNIT))
80 		__vlv_punit_get(i915);
81 
82 	mutex_lock(&i915->sb_lock);
83 }
84 
vlv_iosf_sb_put(struct drm_i915_private * i915,unsigned long ports)85 void vlv_iosf_sb_put(struct drm_i915_private *i915, unsigned long ports)
86 {
87 	mutex_unlock(&i915->sb_lock);
88 
89 	if (ports & BIT(VLV_IOSF_SB_PUNIT))
90 		__vlv_punit_put(i915);
91 }
92 
vlv_sideband_rw(struct drm_i915_private * i915,u32 devfn,u32 port,u32 opcode,u32 addr,u32 * val)93 static int vlv_sideband_rw(struct drm_i915_private *i915,
94 			   u32 devfn, u32 port, u32 opcode,
95 			   u32 addr, u32 *val)
96 {
97 	struct intel_uncore *uncore = &i915->uncore;
98 	const bool is_read = (opcode == SB_MRD_NP || opcode == SB_CRRDDA_NP);
99 	int err;
100 
101 	lockdep_assert_held(&i915->sb_lock);
102 	if (port == IOSF_PORT_PUNIT)
103 		iosf_mbi_assert_punit_acquired();
104 
105 	/* Flush the previous comms, just in case it failed last time. */
106 	if (intel_wait_for_register(uncore,
107 				    VLV_IOSF_DOORBELL_REQ, IOSF_SB_BUSY, 0,
108 				    5)) {
109 		drm_dbg(&i915->drm, "IOSF sideband idle wait (%s) timed out\n",
110 			is_read ? "read" : "write");
111 		return -EAGAIN;
112 	}
113 
114 	preempt_disable();
115 
116 	intel_uncore_write_fw(uncore, VLV_IOSF_ADDR, addr);
117 	intel_uncore_write_fw(uncore, VLV_IOSF_DATA, is_read ? 0 : *val);
118 	intel_uncore_write_fw(uncore, VLV_IOSF_DOORBELL_REQ,
119 			      (devfn << IOSF_DEVFN_SHIFT) |
120 			      (opcode << IOSF_OPCODE_SHIFT) |
121 			      (port << IOSF_PORT_SHIFT) |
122 			      (0xf << IOSF_BYTE_ENABLES_SHIFT) |
123 			      (0 << IOSF_BAR_SHIFT) |
124 			      IOSF_SB_BUSY);
125 
126 	if (__intel_wait_for_register_fw(uncore,
127 					 VLV_IOSF_DOORBELL_REQ, IOSF_SB_BUSY, 0,
128 					 10000, 0, NULL) == 0) {
129 		if (is_read)
130 			*val = intel_uncore_read_fw(uncore, VLV_IOSF_DATA);
131 		err = 0;
132 	} else {
133 		drm_dbg(&i915->drm, "IOSF sideband finish wait (%s) timed out\n",
134 			is_read ? "read" : "write");
135 		err = -ETIMEDOUT;
136 	}
137 
138 	preempt_enable();
139 
140 	return err;
141 }
142 
vlv_punit_read(struct drm_i915_private * i915,u32 addr)143 u32 vlv_punit_read(struct drm_i915_private *i915, u32 addr)
144 {
145 	u32 val = 0;
146 
147 	vlv_sideband_rw(i915, PCI_DEVFN(0, 0), IOSF_PORT_PUNIT,
148 			SB_CRRDDA_NP, addr, &val);
149 
150 	return val;
151 }
152 
vlv_punit_write(struct drm_i915_private * i915,u32 addr,u32 val)153 int vlv_punit_write(struct drm_i915_private *i915, u32 addr, u32 val)
154 {
155 	return vlv_sideband_rw(i915, PCI_DEVFN(0, 0), IOSF_PORT_PUNIT,
156 			       SB_CRWRDA_NP, addr, &val);
157 }
158 
vlv_bunit_read(struct drm_i915_private * i915,u32 reg)159 u32 vlv_bunit_read(struct drm_i915_private *i915, u32 reg)
160 {
161 	u32 val = 0;
162 
163 	vlv_sideband_rw(i915, PCI_DEVFN(0, 0), IOSF_PORT_BUNIT,
164 			SB_CRRDDA_NP, reg, &val);
165 
166 	return val;
167 }
168 
vlv_bunit_write(struct drm_i915_private * i915,u32 reg,u32 val)169 void vlv_bunit_write(struct drm_i915_private *i915, u32 reg, u32 val)
170 {
171 	vlv_sideband_rw(i915, PCI_DEVFN(0, 0), IOSF_PORT_BUNIT,
172 			SB_CRWRDA_NP, reg, &val);
173 }
174 
vlv_nc_read(struct drm_i915_private * i915,u8 addr)175 u32 vlv_nc_read(struct drm_i915_private *i915, u8 addr)
176 {
177 	u32 val = 0;
178 
179 	vlv_sideband_rw(i915, PCI_DEVFN(0, 0), IOSF_PORT_NC,
180 			SB_CRRDDA_NP, addr, &val);
181 
182 	return val;
183 }
184 
vlv_iosf_sb_read(struct drm_i915_private * i915,u8 port,u32 reg)185 u32 vlv_iosf_sb_read(struct drm_i915_private *i915, u8 port, u32 reg)
186 {
187 	u32 val = 0;
188 
189 	vlv_sideband_rw(i915, PCI_DEVFN(0, 0), port,
190 			SB_CRRDDA_NP, reg, &val);
191 
192 	return val;
193 }
194 
vlv_iosf_sb_write(struct drm_i915_private * i915,u8 port,u32 reg,u32 val)195 void vlv_iosf_sb_write(struct drm_i915_private *i915,
196 		       u8 port, u32 reg, u32 val)
197 {
198 	vlv_sideband_rw(i915, PCI_DEVFN(0, 0), port,
199 			SB_CRWRDA_NP, reg, &val);
200 }
201 
vlv_cck_read(struct drm_i915_private * i915,u32 reg)202 u32 vlv_cck_read(struct drm_i915_private *i915, u32 reg)
203 {
204 	u32 val = 0;
205 
206 	vlv_sideband_rw(i915, PCI_DEVFN(0, 0), IOSF_PORT_CCK,
207 			SB_CRRDDA_NP, reg, &val);
208 
209 	return val;
210 }
211 
vlv_cck_write(struct drm_i915_private * i915,u32 reg,u32 val)212 void vlv_cck_write(struct drm_i915_private *i915, u32 reg, u32 val)
213 {
214 	vlv_sideband_rw(i915, PCI_DEVFN(0, 0), IOSF_PORT_CCK,
215 			SB_CRWRDA_NP, reg, &val);
216 }
217 
vlv_ccu_read(struct drm_i915_private * i915,u32 reg)218 u32 vlv_ccu_read(struct drm_i915_private *i915, u32 reg)
219 {
220 	u32 val = 0;
221 
222 	vlv_sideband_rw(i915, PCI_DEVFN(0, 0), IOSF_PORT_CCU,
223 			SB_CRRDDA_NP, reg, &val);
224 
225 	return val;
226 }
227 
vlv_ccu_write(struct drm_i915_private * i915,u32 reg,u32 val)228 void vlv_ccu_write(struct drm_i915_private *i915, u32 reg, u32 val)
229 {
230 	vlv_sideband_rw(i915, PCI_DEVFN(0, 0), IOSF_PORT_CCU,
231 			SB_CRWRDA_NP, reg, &val);
232 }
233 
vlv_dpio_phy_iosf_port(struct drm_i915_private * i915,enum dpio_phy phy)234 static u32 vlv_dpio_phy_iosf_port(struct drm_i915_private *i915, enum dpio_phy phy)
235 {
236 	/*
237 	 * IOSF_PORT_DPIO: VLV x2 PHY (DP/HDMI B and C), CHV x1 PHY (DP/HDMI D)
238 	 * IOSF_PORT_DPIO_2: CHV x2 PHY (DP/HDMI B and C)
239 	 */
240 	if (IS_CHERRYVIEW(i915))
241 		return phy == DPIO_PHY0 ? IOSF_PORT_DPIO_2 : IOSF_PORT_DPIO;
242 	else
243 		return IOSF_PORT_DPIO;
244 }
245 
vlv_dpio_read(struct drm_i915_private * i915,enum pipe pipe,int reg)246 u32 vlv_dpio_read(struct drm_i915_private *i915, enum pipe pipe, int reg)
247 {
248 	u32 port = vlv_dpio_phy_iosf_port(i915, DPIO_PHY(pipe));
249 	u32 val = 0;
250 
251 	vlv_sideband_rw(i915, DPIO_DEVFN, port, SB_MRD_NP, reg, &val);
252 
253 	/*
254 	 * FIXME: There might be some registers where all 1's is a valid value,
255 	 * so ideally we should check the register offset instead...
256 	 */
257 	drm_WARN(&i915->drm, val == 0xffffffff,
258 		 "DPIO read pipe %c reg 0x%x == 0x%x\n",
259 		 pipe_name(pipe), reg, val);
260 
261 	return val;
262 }
263 
vlv_dpio_write(struct drm_i915_private * i915,enum pipe pipe,int reg,u32 val)264 void vlv_dpio_write(struct drm_i915_private *i915,
265 		    enum pipe pipe, int reg, u32 val)
266 {
267 	u32 port = vlv_dpio_phy_iosf_port(i915, DPIO_PHY(pipe));
268 
269 	vlv_sideband_rw(i915, DPIO_DEVFN, port, SB_MWR_NP, reg, &val);
270 }
271 
vlv_flisdsi_read(struct drm_i915_private * i915,u32 reg)272 u32 vlv_flisdsi_read(struct drm_i915_private *i915, u32 reg)
273 {
274 	u32 val = 0;
275 
276 	vlv_sideband_rw(i915, DPIO_DEVFN, IOSF_PORT_FLISDSI, SB_CRRDDA_NP,
277 			reg, &val);
278 	return val;
279 }
280 
vlv_flisdsi_write(struct drm_i915_private * i915,u32 reg,u32 val)281 void vlv_flisdsi_write(struct drm_i915_private *i915, u32 reg, u32 val)
282 {
283 	vlv_sideband_rw(i915, DPIO_DEVFN, IOSF_PORT_FLISDSI, SB_CRWRDA_NP,
284 			reg, &val);
285 }
286 
287 /* SBI access */
intel_sbi_rw(struct drm_i915_private * i915,u16 reg,enum intel_sbi_destination destination,u32 * val,bool is_read)288 static int intel_sbi_rw(struct drm_i915_private *i915, u16 reg,
289 			enum intel_sbi_destination destination,
290 			u32 *val, bool is_read)
291 {
292 	struct intel_uncore *uncore = &i915->uncore;
293 	u32 cmd;
294 
295 	lockdep_assert_held(&i915->sb_lock);
296 
297 	if (intel_wait_for_register_fw(uncore,
298 				       SBI_CTL_STAT, SBI_BUSY, 0,
299 				       100)) {
300 		drm_err(&i915->drm,
301 			"timeout waiting for SBI to become ready\n");
302 		return -EBUSY;
303 	}
304 
305 	intel_uncore_write_fw(uncore, SBI_ADDR, (u32)reg << 16);
306 	intel_uncore_write_fw(uncore, SBI_DATA, is_read ? 0 : *val);
307 
308 	if (destination == SBI_ICLK)
309 		cmd = SBI_CTL_DEST_ICLK | SBI_CTL_OP_CRRD;
310 	else
311 		cmd = SBI_CTL_DEST_MPHY | SBI_CTL_OP_IORD;
312 	if (!is_read)
313 		cmd |= BIT(8);
314 	intel_uncore_write_fw(uncore, SBI_CTL_STAT, cmd | SBI_BUSY);
315 
316 	if (__intel_wait_for_register_fw(uncore,
317 					 SBI_CTL_STAT, SBI_BUSY, 0,
318 					 100, 100, &cmd)) {
319 		drm_err(&i915->drm,
320 			"timeout waiting for SBI to complete read\n");
321 		return -ETIMEDOUT;
322 	}
323 
324 	if (cmd & SBI_RESPONSE_FAIL) {
325 		drm_err(&i915->drm, "error during SBI read of reg %x\n", reg);
326 		return -ENXIO;
327 	}
328 
329 	if (is_read)
330 		*val = intel_uncore_read_fw(uncore, SBI_DATA);
331 
332 	return 0;
333 }
334 
intel_sbi_read(struct drm_i915_private * i915,u16 reg,enum intel_sbi_destination destination)335 u32 intel_sbi_read(struct drm_i915_private *i915, u16 reg,
336 		   enum intel_sbi_destination destination)
337 {
338 	u32 result = 0;
339 
340 	intel_sbi_rw(i915, reg, destination, &result, true);
341 
342 	return result;
343 }
344 
intel_sbi_write(struct drm_i915_private * i915,u16 reg,u32 value,enum intel_sbi_destination destination)345 void intel_sbi_write(struct drm_i915_private *i915, u16 reg, u32 value,
346 		     enum intel_sbi_destination destination)
347 {
348 	intel_sbi_rw(i915, reg, destination, &value, false);
349 }
350 
gen6_check_mailbox_status(u32 mbox)351 static int gen6_check_mailbox_status(u32 mbox)
352 {
353 	switch (mbox & GEN6_PCODE_ERROR_MASK) {
354 	case GEN6_PCODE_SUCCESS:
355 		return 0;
356 	case GEN6_PCODE_UNIMPLEMENTED_CMD:
357 		return -ENODEV;
358 	case GEN6_PCODE_ILLEGAL_CMD:
359 		return -ENXIO;
360 	case GEN6_PCODE_MIN_FREQ_TABLE_GT_RATIO_OUT_OF_RANGE:
361 	case GEN7_PCODE_MIN_FREQ_TABLE_GT_RATIO_OUT_OF_RANGE:
362 		return -EOVERFLOW;
363 	case GEN6_PCODE_TIMEOUT:
364 		return -ETIMEDOUT;
365 	default:
366 		MISSING_CASE(mbox & GEN6_PCODE_ERROR_MASK);
367 		return 0;
368 	}
369 }
370 
gen7_check_mailbox_status(u32 mbox)371 static int gen7_check_mailbox_status(u32 mbox)
372 {
373 	switch (mbox & GEN6_PCODE_ERROR_MASK) {
374 	case GEN6_PCODE_SUCCESS:
375 		return 0;
376 	case GEN6_PCODE_ILLEGAL_CMD:
377 		return -ENXIO;
378 	case GEN7_PCODE_TIMEOUT:
379 		return -ETIMEDOUT;
380 	case GEN7_PCODE_ILLEGAL_DATA:
381 		return -EINVAL;
382 	case GEN11_PCODE_ILLEGAL_SUBCOMMAND:
383 		return -ENXIO;
384 	case GEN11_PCODE_LOCKED:
385 		return -EBUSY;
386 	case GEN11_PCODE_REJECTED:
387 		return -EACCES;
388 	case GEN7_PCODE_MIN_FREQ_TABLE_GT_RATIO_OUT_OF_RANGE:
389 		return -EOVERFLOW;
390 	default:
391 		MISSING_CASE(mbox & GEN6_PCODE_ERROR_MASK);
392 		return 0;
393 	}
394 }
395 
__sandybridge_pcode_rw(struct drm_i915_private * i915,u32 mbox,u32 * val,u32 * val1,int fast_timeout_us,int slow_timeout_ms,bool is_read)396 static int __sandybridge_pcode_rw(struct drm_i915_private *i915,
397 				  u32 mbox, u32 *val, u32 *val1,
398 				  int fast_timeout_us,
399 				  int slow_timeout_ms,
400 				  bool is_read)
401 {
402 	struct intel_uncore *uncore = &i915->uncore;
403 
404 	lockdep_assert_held(&i915->sb_lock);
405 
406 	/*
407 	 * GEN6_PCODE_* are outside of the forcewake domain, we can
408 	 * use te fw I915_READ variants to reduce the amount of work
409 	 * required when reading/writing.
410 	 */
411 
412 	if (intel_uncore_read_fw(uncore, GEN6_PCODE_MAILBOX) & GEN6_PCODE_READY)
413 		return -EAGAIN;
414 
415 	intel_uncore_write_fw(uncore, GEN6_PCODE_DATA, *val);
416 	intel_uncore_write_fw(uncore, GEN6_PCODE_DATA1, val1 ? *val1 : 0);
417 	intel_uncore_write_fw(uncore,
418 			      GEN6_PCODE_MAILBOX, GEN6_PCODE_READY | mbox);
419 
420 	if (__intel_wait_for_register_fw(uncore,
421 					 GEN6_PCODE_MAILBOX,
422 					 GEN6_PCODE_READY, 0,
423 					 fast_timeout_us,
424 					 slow_timeout_ms,
425 					 &mbox))
426 		return -ETIMEDOUT;
427 
428 	if (is_read)
429 		*val = intel_uncore_read_fw(uncore, GEN6_PCODE_DATA);
430 	if (is_read && val1)
431 		*val1 = intel_uncore_read_fw(uncore, GEN6_PCODE_DATA1);
432 
433 	if (INTEL_GEN(i915) > 6)
434 		return gen7_check_mailbox_status(mbox);
435 	else
436 		return gen6_check_mailbox_status(mbox);
437 }
438 
sandybridge_pcode_read(struct drm_i915_private * i915,u32 mbox,u32 * val,u32 * val1)439 int sandybridge_pcode_read(struct drm_i915_private *i915, u32 mbox,
440 			   u32 *val, u32 *val1)
441 {
442 	int err;
443 
444 	mutex_lock(&i915->sb_lock);
445 	err = __sandybridge_pcode_rw(i915, mbox, val, val1,
446 				     500, 20,
447 				     true);
448 	mutex_unlock(&i915->sb_lock);
449 
450 	if (err) {
451 		drm_dbg(&i915->drm,
452 			"warning: pcode (read from mbox %x) mailbox access failed for %ps: %d\n",
453 			mbox, __builtin_return_address(0), err);
454 	}
455 
456 	return err;
457 }
458 
sandybridge_pcode_write_timeout(struct drm_i915_private * i915,u32 mbox,u32 val,int fast_timeout_us,int slow_timeout_ms)459 int sandybridge_pcode_write_timeout(struct drm_i915_private *i915,
460 				    u32 mbox, u32 val,
461 				    int fast_timeout_us,
462 				    int slow_timeout_ms)
463 {
464 	int err;
465 
466 	mutex_lock(&i915->sb_lock);
467 	err = __sandybridge_pcode_rw(i915, mbox, &val, NULL,
468 				     fast_timeout_us, slow_timeout_ms,
469 				     false);
470 	mutex_unlock(&i915->sb_lock);
471 
472 	if (err) {
473 		drm_dbg(&i915->drm,
474 			"warning: pcode (write of 0x%08x to mbox %x) mailbox access failed for %ps: %d\n",
475 			val, mbox, __builtin_return_address(0), err);
476 	}
477 
478 	return err;
479 }
480 
skl_pcode_try_request(struct drm_i915_private * i915,u32 mbox,u32 request,u32 reply_mask,u32 reply,u32 * status)481 static bool skl_pcode_try_request(struct drm_i915_private *i915, u32 mbox,
482 				  u32 request, u32 reply_mask, u32 reply,
483 				  u32 *status)
484 {
485 	*status = __sandybridge_pcode_rw(i915, mbox, &request, NULL,
486 					 500, 0,
487 					 true);
488 
489 	return *status || ((request & reply_mask) == reply);
490 }
491 
492 /**
493  * skl_pcode_request - send PCODE request until acknowledgment
494  * @i915: device private
495  * @mbox: PCODE mailbox ID the request is targeted for
496  * @request: request ID
497  * @reply_mask: mask used to check for request acknowledgment
498  * @reply: value used to check for request acknowledgment
499  * @timeout_base_ms: timeout for polling with preemption enabled
500  *
501  * Keep resending the @request to @mbox until PCODE acknowledges it, PCODE
502  * reports an error or an overall timeout of @timeout_base_ms+50 ms expires.
503  * The request is acknowledged once the PCODE reply dword equals @reply after
504  * applying @reply_mask. Polling is first attempted with preemption enabled
505  * for @timeout_base_ms and if this times out for another 50 ms with
506  * preemption disabled.
507  *
508  * Returns 0 on success, %-ETIMEDOUT in case of a timeout, <0 in case of some
509  * other error as reported by PCODE.
510  */
skl_pcode_request(struct drm_i915_private * i915,u32 mbox,u32 request,u32 reply_mask,u32 reply,int timeout_base_ms)511 int skl_pcode_request(struct drm_i915_private *i915, u32 mbox, u32 request,
512 		      u32 reply_mask, u32 reply, int timeout_base_ms)
513 {
514 	u32 status;
515 	int ret;
516 
517 	mutex_lock(&i915->sb_lock);
518 
519 #define COND \
520 	skl_pcode_try_request(i915, mbox, request, reply_mask, reply, &status)
521 
522 	/*
523 	 * Prime the PCODE by doing a request first. Normally it guarantees
524 	 * that a subsequent request, at most @timeout_base_ms later, succeeds.
525 	 * _wait_for() doesn't guarantee when its passed condition is evaluated
526 	 * first, so send the first request explicitly.
527 	 */
528 	if (COND) {
529 		ret = 0;
530 		goto out;
531 	}
532 	ret = _wait_for(COND, timeout_base_ms * 1000, 10, 10);
533 	if (!ret)
534 		goto out;
535 
536 	/*
537 	 * The above can time out if the number of requests was low (2 in the
538 	 * worst case) _and_ PCODE was busy for some reason even after a
539 	 * (queued) request and @timeout_base_ms delay. As a workaround retry
540 	 * the poll with preemption disabled to maximize the number of
541 	 * requests. Increase the timeout from @timeout_base_ms to 50ms to
542 	 * account for interrupts that could reduce the number of these
543 	 * requests, and for any quirks of the PCODE firmware that delays
544 	 * the request completion.
545 	 */
546 	drm_dbg_kms(&i915->drm,
547 		    "PCODE timeout, retrying with preemption disabled\n");
548 	drm_WARN_ON_ONCE(&i915->drm, timeout_base_ms > 3);
549 	preempt_disable();
550 	ret = wait_for_atomic(COND, 50);
551 	preempt_enable();
552 
553 out:
554 	mutex_unlock(&i915->sb_lock);
555 	return ret ? ret : status;
556 #undef COND
557 }
558