xref: /openbmc/linux/arch/x86/kernel/early-quirks.c (revision b34e08d5)
1 /* Various workarounds for chipset bugs.
2    This code runs very early and can't use the regular PCI subsystem
3    The entries are keyed to PCI bridges which usually identify chipsets
4    uniquely.
5    This is only for whole classes of chipsets with specific problems which
6    need early invasive action (e.g. before the timers are initialized).
7    Most PCI device specific workarounds can be done later and should be
8    in standard PCI quirks
9    Mainboard specific bugs should be handled by DMI entries.
10    CPU specific bugs in setup.c */
11 
12 #include <linux/pci.h>
13 #include <linux/acpi.h>
14 #include <linux/pci_ids.h>
15 #include <drm/i915_drm.h>
16 #include <asm/pci-direct.h>
17 #include <asm/dma.h>
18 #include <asm/io_apic.h>
19 #include <asm/apic.h>
20 #include <asm/iommu.h>
21 #include <asm/gart.h>
22 #include <asm/irq_remapping.h>
23 
24 static void __init fix_hypertransport_config(int num, int slot, int func)
25 {
26 	u32 htcfg;
27 	/*
28 	 * we found a hypertransport bus
29 	 * make sure that we are broadcasting
30 	 * interrupts to all cpus on the ht bus
31 	 * if we're using extended apic ids
32 	 */
33 	htcfg = read_pci_config(num, slot, func, 0x68);
34 	if (htcfg & (1 << 18)) {
35 		printk(KERN_INFO "Detected use of extended apic ids "
36 				 "on hypertransport bus\n");
37 		if ((htcfg & (1 << 17)) == 0) {
38 			printk(KERN_INFO "Enabling hypertransport extended "
39 					 "apic interrupt broadcast\n");
40 			printk(KERN_INFO "Note this is a bios bug, "
41 					 "please contact your hw vendor\n");
42 			htcfg |= (1 << 17);
43 			write_pci_config(num, slot, func, 0x68, htcfg);
44 		}
45 	}
46 
47 
48 }
49 
50 static void __init via_bugs(int  num, int slot, int func)
51 {
52 #ifdef CONFIG_GART_IOMMU
53 	if ((max_pfn > MAX_DMA32_PFN ||  force_iommu) &&
54 	    !gart_iommu_aperture_allowed) {
55 		printk(KERN_INFO
56 		       "Looks like a VIA chipset. Disabling IOMMU."
57 		       " Override with iommu=allowed\n");
58 		gart_iommu_aperture_disabled = 1;
59 	}
60 #endif
61 }
62 
63 #ifdef CONFIG_ACPI
64 #ifdef CONFIG_X86_IO_APIC
65 
66 static int __init nvidia_hpet_check(struct acpi_table_header *header)
67 {
68 	return 0;
69 }
70 #endif /* CONFIG_X86_IO_APIC */
71 #endif /* CONFIG_ACPI */
72 
73 static void __init nvidia_bugs(int num, int slot, int func)
74 {
75 #ifdef CONFIG_ACPI
76 #ifdef CONFIG_X86_IO_APIC
77 	/*
78 	 * All timer overrides on Nvidia are
79 	 * wrong unless HPET is enabled.
80 	 * Unfortunately that's not true on many Asus boards.
81 	 * We don't know yet how to detect this automatically, but
82 	 * at least allow a command line override.
83 	 */
84 	if (acpi_use_timer_override)
85 		return;
86 
87 	if (acpi_table_parse(ACPI_SIG_HPET, nvidia_hpet_check)) {
88 		acpi_skip_timer_override = 1;
89 		printk(KERN_INFO "Nvidia board "
90 		       "detected. Ignoring ACPI "
91 		       "timer override.\n");
92 		printk(KERN_INFO "If you got timer trouble "
93 			"try acpi_use_timer_override\n");
94 	}
95 #endif
96 #endif
97 	/* RED-PEN skip them on mptables too? */
98 
99 }
100 
101 #if defined(CONFIG_ACPI) && defined(CONFIG_X86_IO_APIC)
102 static u32 __init ati_ixp4x0_rev(int num, int slot, int func)
103 {
104 	u32 d;
105 	u8  b;
106 
107 	b = read_pci_config_byte(num, slot, func, 0xac);
108 	b &= ~(1<<5);
109 	write_pci_config_byte(num, slot, func, 0xac, b);
110 
111 	d = read_pci_config(num, slot, func, 0x70);
112 	d |= 1<<8;
113 	write_pci_config(num, slot, func, 0x70, d);
114 
115 	d = read_pci_config(num, slot, func, 0x8);
116 	d &= 0xff;
117 	return d;
118 }
119 
120 static void __init ati_bugs(int num, int slot, int func)
121 {
122 	u32 d;
123 	u8  b;
124 
125 	if (acpi_use_timer_override)
126 		return;
127 
128 	d = ati_ixp4x0_rev(num, slot, func);
129 	if (d  < 0x82)
130 		acpi_skip_timer_override = 1;
131 	else {
132 		/* check for IRQ0 interrupt swap */
133 		outb(0x72, 0xcd6); b = inb(0xcd7);
134 		if (!(b & 0x2))
135 			acpi_skip_timer_override = 1;
136 	}
137 
138 	if (acpi_skip_timer_override) {
139 		printk(KERN_INFO "SB4X0 revision 0x%x\n", d);
140 		printk(KERN_INFO "Ignoring ACPI timer override.\n");
141 		printk(KERN_INFO "If you got timer trouble "
142 		       "try acpi_use_timer_override\n");
143 	}
144 }
145 
146 static u32 __init ati_sbx00_rev(int num, int slot, int func)
147 {
148 	u32 d;
149 
150 	d = read_pci_config(num, slot, func, 0x8);
151 	d &= 0xff;
152 
153 	return d;
154 }
155 
156 static void __init ati_bugs_contd(int num, int slot, int func)
157 {
158 	u32 d, rev;
159 
160 	rev = ati_sbx00_rev(num, slot, func);
161 	if (rev >= 0x40)
162 		acpi_fix_pin2_polarity = 1;
163 
164 	/*
165 	 * SB600: revisions 0x11, 0x12, 0x13, 0x14, ...
166 	 * SB700: revisions 0x39, 0x3a, ...
167 	 * SB800: revisions 0x40, 0x41, ...
168 	 */
169 	if (rev >= 0x39)
170 		return;
171 
172 	if (acpi_use_timer_override)
173 		return;
174 
175 	/* check for IRQ0 interrupt swap */
176 	d = read_pci_config(num, slot, func, 0x64);
177 	if (!(d & (1<<14)))
178 		acpi_skip_timer_override = 1;
179 
180 	if (acpi_skip_timer_override) {
181 		printk(KERN_INFO "SB600 revision 0x%x\n", rev);
182 		printk(KERN_INFO "Ignoring ACPI timer override.\n");
183 		printk(KERN_INFO "If you got timer trouble "
184 		       "try acpi_use_timer_override\n");
185 	}
186 }
187 #else
188 static void __init ati_bugs(int num, int slot, int func)
189 {
190 }
191 
192 static void __init ati_bugs_contd(int num, int slot, int func)
193 {
194 }
195 #endif
196 
197 static void __init intel_remapping_check(int num, int slot, int func)
198 {
199 	u8 revision;
200 	u16 device;
201 
202 	device = read_pci_config_16(num, slot, func, PCI_DEVICE_ID);
203 	revision = read_pci_config_byte(num, slot, func, PCI_REVISION_ID);
204 
205 	/*
206 	 * Revision <= 13 of all triggering devices id in this quirk
207 	 * have a problem draining interrupts when irq remapping is
208 	 * enabled, and should be flagged as broken. Additionally
209 	 * revision 0x22 of device id 0x3405 has this problem.
210 	 */
211 	if (revision <= 0x13)
212 		set_irq_remapping_broken();
213 	else if (device == 0x3405 && revision == 0x22)
214 		set_irq_remapping_broken();
215 }
216 
217 /*
218  * Systems with Intel graphics controllers set aside memory exclusively
219  * for gfx driver use.  This memory is not marked in the E820 as reserved
220  * or as RAM, and so is subject to overlap from E820 manipulation later
221  * in the boot process.  On some systems, MMIO space is allocated on top,
222  * despite the efforts of the "RAM buffer" approach, which simply rounds
223  * memory boundaries up to 64M to try to catch space that may decode
224  * as RAM and so is not suitable for MMIO.
225  *
226  * And yes, so far on current devices the base addr is always under 4G.
227  */
228 static u32 __init intel_stolen_base(int num, int slot, int func, size_t stolen_size)
229 {
230 	u32 base;
231 
232 	/*
233 	 * For the PCI IDs in this quirk, the stolen base is always
234 	 * in 0x5c, aka the BDSM register (yes that's really what
235 	 * it's called).
236 	 */
237 	base = read_pci_config(num, slot, func, 0x5c);
238 	base &= ~((1<<20) - 1);
239 
240 	return base;
241 }
242 
243 #define KB(x)	((x) * 1024)
244 #define MB(x)	(KB (KB (x)))
245 #define GB(x)	(MB (KB (x)))
246 
247 static size_t __init i830_tseg_size(void)
248 {
249 	u8 tmp = read_pci_config_byte(0, 0, 0, I830_ESMRAMC);
250 
251 	if (!(tmp & TSEG_ENABLE))
252 		return 0;
253 
254 	if (tmp & I830_TSEG_SIZE_1M)
255 		return MB(1);
256 	else
257 		return KB(512);
258 }
259 
260 static size_t __init i845_tseg_size(void)
261 {
262 	u8 tmp = read_pci_config_byte(0, 0, 0, I845_ESMRAMC);
263 
264 	if (!(tmp & TSEG_ENABLE))
265 		return 0;
266 
267 	switch (tmp & I845_TSEG_SIZE_MASK) {
268 	case I845_TSEG_SIZE_512K:
269 		return KB(512);
270 	case I845_TSEG_SIZE_1M:
271 		return MB(1);
272 	default:
273 		WARN_ON(1);
274 		return 0;
275 	}
276 }
277 
278 static size_t __init i85x_tseg_size(void)
279 {
280 	u8 tmp = read_pci_config_byte(0, 0, 0, I85X_ESMRAMC);
281 
282 	if (!(tmp & TSEG_ENABLE))
283 		return 0;
284 
285 	return MB(1);
286 }
287 
288 static size_t __init i830_mem_size(void)
289 {
290 	return read_pci_config_byte(0, 0, 0, I830_DRB3) * MB(32);
291 }
292 
293 static size_t __init i85x_mem_size(void)
294 {
295 	return read_pci_config_byte(0, 0, 1, I85X_DRB3) * MB(32);
296 }
297 
298 /*
299  * On 830/845/85x the stolen memory base isn't available in any
300  * register. We need to calculate it as TOM-TSEG_SIZE-stolen_size.
301  */
302 static u32 __init i830_stolen_base(int num, int slot, int func, size_t stolen_size)
303 {
304 	return i830_mem_size() - i830_tseg_size() - stolen_size;
305 }
306 
307 static u32 __init i845_stolen_base(int num, int slot, int func, size_t stolen_size)
308 {
309 	return i830_mem_size() - i845_tseg_size() - stolen_size;
310 }
311 
312 static u32 __init i85x_stolen_base(int num, int slot, int func, size_t stolen_size)
313 {
314 	return i85x_mem_size() - i85x_tseg_size() - stolen_size;
315 }
316 
317 static u32 __init i865_stolen_base(int num, int slot, int func, size_t stolen_size)
318 {
319 	/*
320 	 * FIXME is the graphics stolen memory region
321 	 * always at TOUD? Ie. is it always the last
322 	 * one to be allocated by the BIOS?
323 	 */
324 	return read_pci_config_16(0, 0, 0, I865_TOUD) << 16;
325 }
326 
327 static size_t __init i830_stolen_size(int num, int slot, int func)
328 {
329 	size_t stolen_size;
330 	u16 gmch_ctrl;
331 
332 	gmch_ctrl = read_pci_config_16(0, 0, 0, I830_GMCH_CTRL);
333 
334 	switch (gmch_ctrl & I830_GMCH_GMS_MASK) {
335 	case I830_GMCH_GMS_STOLEN_512:
336 		stolen_size = KB(512);
337 		break;
338 	case I830_GMCH_GMS_STOLEN_1024:
339 		stolen_size = MB(1);
340 		break;
341 	case I830_GMCH_GMS_STOLEN_8192:
342 		stolen_size = MB(8);
343 		break;
344 	case I830_GMCH_GMS_LOCAL:
345 		/* local memory isn't part of the normal address space */
346 		stolen_size = 0;
347 		break;
348 	default:
349 		return 0;
350 	}
351 
352 	return stolen_size;
353 }
354 
355 static size_t __init gen3_stolen_size(int num, int slot, int func)
356 {
357 	size_t stolen_size;
358 	u16 gmch_ctrl;
359 
360 	gmch_ctrl = read_pci_config_16(0, 0, 0, I830_GMCH_CTRL);
361 
362 	switch (gmch_ctrl & I855_GMCH_GMS_MASK) {
363 	case I855_GMCH_GMS_STOLEN_1M:
364 		stolen_size = MB(1);
365 		break;
366 	case I855_GMCH_GMS_STOLEN_4M:
367 		stolen_size = MB(4);
368 		break;
369 	case I855_GMCH_GMS_STOLEN_8M:
370 		stolen_size = MB(8);
371 		break;
372 	case I855_GMCH_GMS_STOLEN_16M:
373 		stolen_size = MB(16);
374 		break;
375 	case I855_GMCH_GMS_STOLEN_32M:
376 		stolen_size = MB(32);
377 		break;
378 	case I915_GMCH_GMS_STOLEN_48M:
379 		stolen_size = MB(48);
380 		break;
381 	case I915_GMCH_GMS_STOLEN_64M:
382 		stolen_size = MB(64);
383 		break;
384 	case G33_GMCH_GMS_STOLEN_128M:
385 		stolen_size = MB(128);
386 		break;
387 	case G33_GMCH_GMS_STOLEN_256M:
388 		stolen_size = MB(256);
389 		break;
390 	case INTEL_GMCH_GMS_STOLEN_96M:
391 		stolen_size = MB(96);
392 		break;
393 	case INTEL_GMCH_GMS_STOLEN_160M:
394 		stolen_size = MB(160);
395 		break;
396 	case INTEL_GMCH_GMS_STOLEN_224M:
397 		stolen_size = MB(224);
398 		break;
399 	case INTEL_GMCH_GMS_STOLEN_352M:
400 		stolen_size = MB(352);
401 		break;
402 	default:
403 		stolen_size = 0;
404 		break;
405 	}
406 
407 	return stolen_size;
408 }
409 
410 static size_t __init gen6_stolen_size(int num, int slot, int func)
411 {
412 	u16 gmch_ctrl;
413 
414 	gmch_ctrl = read_pci_config_16(num, slot, func, SNB_GMCH_CTRL);
415 	gmch_ctrl >>= SNB_GMCH_GMS_SHIFT;
416 	gmch_ctrl &= SNB_GMCH_GMS_MASK;
417 
418 	return gmch_ctrl << 25; /* 32 MB units */
419 }
420 
421 static size_t gen8_stolen_size(int num, int slot, int func)
422 {
423 	u16 gmch_ctrl;
424 
425 	gmch_ctrl = read_pci_config_16(num, slot, func, SNB_GMCH_CTRL);
426 	gmch_ctrl >>= BDW_GMCH_GMS_SHIFT;
427 	gmch_ctrl &= BDW_GMCH_GMS_MASK;
428 	return gmch_ctrl << 25; /* 32 MB units */
429 }
430 
431 
432 struct intel_stolen_funcs {
433 	size_t (*size)(int num, int slot, int func);
434 	u32 (*base)(int num, int slot, int func, size_t size);
435 };
436 
437 static const struct intel_stolen_funcs i830_stolen_funcs = {
438 	.base = i830_stolen_base,
439 	.size = i830_stolen_size,
440 };
441 
442 static const struct intel_stolen_funcs i845_stolen_funcs = {
443 	.base = i845_stolen_base,
444 	.size = i830_stolen_size,
445 };
446 
447 static const struct intel_stolen_funcs i85x_stolen_funcs = {
448 	.base = i85x_stolen_base,
449 	.size = gen3_stolen_size,
450 };
451 
452 static const struct intel_stolen_funcs i865_stolen_funcs = {
453 	.base = i865_stolen_base,
454 	.size = gen3_stolen_size,
455 };
456 
457 static const struct intel_stolen_funcs gen3_stolen_funcs = {
458 	.base = intel_stolen_base,
459 	.size = gen3_stolen_size,
460 };
461 
462 static const struct intel_stolen_funcs gen6_stolen_funcs = {
463 	.base = intel_stolen_base,
464 	.size = gen6_stolen_size,
465 };
466 
467 static const struct intel_stolen_funcs gen8_stolen_funcs = {
468 	.base = intel_stolen_base,
469 	.size = gen8_stolen_size,
470 };
471 
472 static struct pci_device_id intel_stolen_ids[] __initdata = {
473 	INTEL_I830_IDS(&i830_stolen_funcs),
474 	INTEL_I845G_IDS(&i845_stolen_funcs),
475 	INTEL_I85X_IDS(&i85x_stolen_funcs),
476 	INTEL_I865G_IDS(&i865_stolen_funcs),
477 	INTEL_I915G_IDS(&gen3_stolen_funcs),
478 	INTEL_I915GM_IDS(&gen3_stolen_funcs),
479 	INTEL_I945G_IDS(&gen3_stolen_funcs),
480 	INTEL_I945GM_IDS(&gen3_stolen_funcs),
481 	INTEL_VLV_M_IDS(&gen6_stolen_funcs),
482 	INTEL_VLV_D_IDS(&gen6_stolen_funcs),
483 	INTEL_PINEVIEW_IDS(&gen3_stolen_funcs),
484 	INTEL_I965G_IDS(&gen3_stolen_funcs),
485 	INTEL_G33_IDS(&gen3_stolen_funcs),
486 	INTEL_I965GM_IDS(&gen3_stolen_funcs),
487 	INTEL_GM45_IDS(&gen3_stolen_funcs),
488 	INTEL_G45_IDS(&gen3_stolen_funcs),
489 	INTEL_IRONLAKE_D_IDS(&gen3_stolen_funcs),
490 	INTEL_IRONLAKE_M_IDS(&gen3_stolen_funcs),
491 	INTEL_SNB_D_IDS(&gen6_stolen_funcs),
492 	INTEL_SNB_M_IDS(&gen6_stolen_funcs),
493 	INTEL_IVB_M_IDS(&gen6_stolen_funcs),
494 	INTEL_IVB_D_IDS(&gen6_stolen_funcs),
495 	INTEL_HSW_D_IDS(&gen6_stolen_funcs),
496 	INTEL_HSW_M_IDS(&gen6_stolen_funcs),
497 	INTEL_BDW_M_IDS(&gen8_stolen_funcs),
498 	INTEL_BDW_D_IDS(&gen8_stolen_funcs)
499 };
500 
501 static void __init intel_graphics_stolen(int num, int slot, int func)
502 {
503 	size_t size;
504 	int i;
505 	u32 start;
506 	u16 device, subvendor, subdevice;
507 
508 	device = read_pci_config_16(num, slot, func, PCI_DEVICE_ID);
509 	subvendor = read_pci_config_16(num, slot, func,
510 				       PCI_SUBSYSTEM_VENDOR_ID);
511 	subdevice = read_pci_config_16(num, slot, func, PCI_SUBSYSTEM_ID);
512 
513 	for (i = 0; i < ARRAY_SIZE(intel_stolen_ids); i++) {
514 		if (intel_stolen_ids[i].device == device) {
515 			const struct intel_stolen_funcs *stolen_funcs =
516 				(const struct intel_stolen_funcs *)intel_stolen_ids[i].driver_data;
517 			size = stolen_funcs->size(num, slot, func);
518 			start = stolen_funcs->base(num, slot, func, size);
519 			if (size && start) {
520 				printk(KERN_INFO "Reserving Intel graphics stolen memory at 0x%x-0x%x\n",
521 				       start, start + (u32)size - 1);
522 				/* Mark this space as reserved */
523 				e820_add_region(start, size, E820_RESERVED);
524 				sanitize_e820_map(e820.map,
525 						  ARRAY_SIZE(e820.map),
526 						  &e820.nr_map);
527 			}
528 			return;
529 		}
530 	}
531 }
532 
533 #define QFLAG_APPLY_ONCE 	0x1
534 #define QFLAG_APPLIED		0x2
535 #define QFLAG_DONE		(QFLAG_APPLY_ONCE|QFLAG_APPLIED)
536 struct chipset {
537 	u32 vendor;
538 	u32 device;
539 	u32 class;
540 	u32 class_mask;
541 	u32 flags;
542 	void (*f)(int num, int slot, int func);
543 };
544 
545 /*
546  * Only works for devices on the root bus. If you add any devices
547  * not on bus 0 readd another loop level in early_quirks(). But
548  * be careful because at least the Nvidia quirk here relies on
549  * only matching on bus 0.
550  */
551 static struct chipset early_qrk[] __initdata = {
552 	{ PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID,
553 	  PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID, QFLAG_APPLY_ONCE, nvidia_bugs },
554 	{ PCI_VENDOR_ID_VIA, PCI_ANY_ID,
555 	  PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID, QFLAG_APPLY_ONCE, via_bugs },
556 	{ PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_K8_NB,
557 	  PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, 0, fix_hypertransport_config },
558 	{ PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_IXP400_SMBUS,
559 	  PCI_CLASS_SERIAL_SMBUS, PCI_ANY_ID, 0, ati_bugs },
560 	{ PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_SBX00_SMBUS,
561 	  PCI_CLASS_SERIAL_SMBUS, PCI_ANY_ID, 0, ati_bugs_contd },
562 	{ PCI_VENDOR_ID_INTEL, 0x3403, PCI_CLASS_BRIDGE_HOST,
563 	  PCI_BASE_CLASS_BRIDGE, 0, intel_remapping_check },
564 	{ PCI_VENDOR_ID_INTEL, 0x3405, PCI_CLASS_BRIDGE_HOST,
565 	  PCI_BASE_CLASS_BRIDGE, 0, intel_remapping_check },
566 	{ PCI_VENDOR_ID_INTEL, 0x3406, PCI_CLASS_BRIDGE_HOST,
567 	  PCI_BASE_CLASS_BRIDGE, 0, intel_remapping_check },
568 	{ PCI_VENDOR_ID_INTEL, PCI_ANY_ID, PCI_CLASS_DISPLAY_VGA, PCI_ANY_ID,
569 	  QFLAG_APPLY_ONCE, intel_graphics_stolen },
570 	{}
571 };
572 
573 /**
574  * check_dev_quirk - apply early quirks to a given PCI device
575  * @num: bus number
576  * @slot: slot number
577  * @func: PCI function
578  *
579  * Check the vendor & device ID against the early quirks table.
580  *
581  * If the device is single function, let early_quirks() know so we don't
582  * poke at this device again.
583  */
584 static int __init check_dev_quirk(int num, int slot, int func)
585 {
586 	u16 class;
587 	u16 vendor;
588 	u16 device;
589 	u8 type;
590 	int i;
591 
592 	class = read_pci_config_16(num, slot, func, PCI_CLASS_DEVICE);
593 
594 	if (class == 0xffff)
595 		return -1; /* no class, treat as single function */
596 
597 	vendor = read_pci_config_16(num, slot, func, PCI_VENDOR_ID);
598 
599 	device = read_pci_config_16(num, slot, func, PCI_DEVICE_ID);
600 
601 	for (i = 0; early_qrk[i].f != NULL; i++) {
602 		if (((early_qrk[i].vendor == PCI_ANY_ID) ||
603 			(early_qrk[i].vendor == vendor)) &&
604 			((early_qrk[i].device == PCI_ANY_ID) ||
605 			(early_qrk[i].device == device)) &&
606 			(!((early_qrk[i].class ^ class) &
607 			    early_qrk[i].class_mask))) {
608 				if ((early_qrk[i].flags &
609 				     QFLAG_DONE) != QFLAG_DONE)
610 					early_qrk[i].f(num, slot, func);
611 				early_qrk[i].flags |= QFLAG_APPLIED;
612 			}
613 	}
614 
615 	type = read_pci_config_byte(num, slot, func,
616 				    PCI_HEADER_TYPE);
617 	if (!(type & 0x80))
618 		return -1;
619 
620 	return 0;
621 }
622 
623 void __init early_quirks(void)
624 {
625 	int slot, func;
626 
627 	if (!early_pci_allowed())
628 		return;
629 
630 	/* Poor man's PCI discovery */
631 	/* Only scan the root bus */
632 	for (slot = 0; slot < 32; slot++)
633 		for (func = 0; func < 8; func++) {
634 			/* Only probe function 0 on single fn devices */
635 			if (check_dev_quirk(0, slot, func))
636 				break;
637 		}
638 }
639