cpu: allwinner h3(cortex-a7) Phenomenon: cpu is enabled ondemand cpufreq frequency modulation, there is no such problem when frequency modulation is not enabled The cpu will be stuck for a period of time in the stuck place described below, and it will recover after a while
Code location:: https://elixir.bootlin.com/linux/v4.19.206/source/drivers/usb/core/hcd.c#L1771 By analyzing the perf output file, __usb_hcd_giveback_urb() will get stuck in these places: c04d35bc __usb_hcd_giveback_urb+0x60 ([kernel.kallsyms]): 1586 times c04d35f4 __usb_hcd_giveback_urb+0x98 ([kernel.kallsyms]): 1 time c04d3590 __usb_hcd_giveback_urb+0x34 ([kernel.kallsyms]): 4 times c04d3574 __usb_hcd_giveback_urb+0x18 ([kernel.kallsyms]): 1 time c04d3580 __usb_hcd_giveback_urb+0x24 ([kernel.kallsyms]): 1 time c04d3598 __usb_hcd_giveback_urb+0x3c ([kernel.kallsyms]): 1 time The less frequent ones are ignored 0000084c <__usb_hcd_giveback_urb>: 84c: e92d4070 push {r4, r5, r6, lr} 850: e3a03000 mov r3, #0 854: e590103c ldr r1, [r0, #60] ; 0x3c 858: e1a04000 mov r4, r0 85c: e5902028 ldr r2, [r0, #40] ; 0x28 860: e3110001 tst r1, #1 864: e5905024 ldr r5, [r0, #36] ; 0x24 868: e5906010 ldr r6, [r0, #16] 86c: e592003c ldr r0, [r2, #60] ; 0x3c 870: e5843004 str r3, [r4, #4] 874: 1a00001b bne 8e8 <__usb_hcd_giveback_urb+0x9c> 878: e1a01004 mov r1, r4 87c: ebffffe1 bl 808 <unmap_urb_for_dma> 880: e1a00005 mov r0, r5 884: ebfffffe bl 0 <usb_anchor_suspend_wakeups> 888: e1a00004 mov r0, r4 88c: ebfffffe bl 0 <usb_unanchor_urb> 890: e5846038 str r6, [r4, #56] ; 0x38 894: e10f6000 mrs r6, CPSR 898: f10c0080 cpsid i 89c: e5943078 ldr r3, [r4, #120] ; 0x78 8a0: e1a00004 mov r0, r4 8a4: e12fff33 blx r3 8a8: e121f006 msr CPSR_c, r6 <----------corresponding statement local_irq_restore(flags); 8ac: e1a00005 mov r0, r5 <-------------__usb_hcd_giveback_urb+0x60 8b0: ebfffffe bl 0 <usb_anchor_resume_wakeups> 8b4: e2843008 add r3, r4, #8 8b8: f593f000 pldw [r3] 8bc: e1932f9f ldrex r2, [r3] 8c0: e2422001 sub r2, r2, #1 8c4: e1831f92 strex r1, r2, [r3] 8c8: e3310000 teq r1, #0 8cc: 1afffffa bne 8bc <__usb_hcd_giveback_urb+0x70> 8d0: e594300c ldr r3, [r4, #12] 8d4: e3530000 cmp r3, #0 8d8: 1a00000c bne 910 <__usb_hcd_giveback_urb+0xc4> 8dc: e1a00004 mov r0, r4 8e0: e8bd4070 pop {r4, r5, r6, lr} 8e4: eafffffe b 0 <usb_free_urb> 8e8: e5941058 ldr r1, [r4, #88] ; 0x58 8ec: e5942054 ldr r2, [r4, #84] ; 0x54 8f0: e1510002 cmp r1, r2 8f4: 23a03000 movcs r3, #0 8f8: 33a03001 movcc r3, #1 8fc: e3560000 cmp r6, #0 900: 13a03000 movne r3, #0 904: e3530000 cmp r3, #0 908: 13e06078 mvnne r6, #120 ; 0x78 90c: eaffffd9 b 878 <__usb_hcd_giveback_urb+0x2c> 910: e3000000 movw r0, #0 914: e3a03000 mov r3, #0 918: e3400000 movt r0, #0 91c: e3a02001 mov r2, #1 920: e3a01003 mov r1, #3 924: ebfffffe bl 0 <__wake_up> 928: e1a00004 mov r0, r4 92c: e8bd4070 pop {r4, r5, r6, lr} 930: eafffffe b 0 <usb_free_urb> Because perf is based on interrupts, it takes a long time to turn off the interrupt. After the interrupt is turned on, the perf event is triggered. After commenting out the local_irq_save() and local_irq_restore() here, it is still stuck. The perf flame graph shows that the function that mainly eats the cpu is mmiocpy() sample call stack: swapper 0 [000] 938.366296: 1642083 cycles:ppp: c070ad4c mmiocpy+0x4c ([kernel.kallsyms]) bf025558 uvc_video_decode_data.constprop.5+0x38 (/lib/modules/4.19.173/kernel/drivers/media/usb/uvc/uvcvideo.ko) bf025610 uvc_video_decode_isoc+0x6c (/lib/modules/4.19.173/kernel/drivers/media/usb/uvc/uvcvideo.ko) bf0242a0 uvc_video_complete+0xb0 (/lib/modules/4.19.173/kernel/drivers/media/usb/uvc/uvcvideo.ko) c04d35b0 __usb_hcd_giveback_urb+0x54 ([kernel.kallsyms]) c04d36e4 usb_giveback_urb_bh+0xac ([kernel.kallsyms]) c0122070 tasklet_action_common.constprop.3+0x64 ([kernel.kallsyms]) c01021fc __softirqentry_text_start+0x114 ([kernel.kallsyms]) c0122400 irq_exit+0xcc ([kernel.kallsyms]) c0162634 __handle_domain_irq+0x60 ([kernel.kallsyms]) c0390a34 gic_handle_irq+0x4c ([kernel.kallsyms]) c0101a0c __irq_svc+0x6c ([kernel.kallsyms]) c01087e8 arch_cpu_idle+0x38 ([kernel.kallsyms]) c0145d78 do_idle+0xe4 ([kernel.kallsyms]) c0146070 cpu_startup_entry+0x18 ([kernel.kallsyms]) c0a00cb8 start_kernel+0x3dc ([kernel.kallsyms]) count statistics: 42 mmiocpy+0x31c 42 mmiocpy+0xf0 210 mmiocpy+0x2b8 229 mmiocpy+0x208 235 mmiocpy+0x2ac 247 mmiocpy+0x1fc 271 mmiocpy+0x158 277 mmiocpy+0x14c 380 mmiocpy+0x4c The last few passes are the stuck points caused by ldm r1!, {...} loading registers from memory. This shows that the cpu core and the memory controller are not compatible with each other. mmiocpy == memcpy, disassembly: arch/arm/lib/memcpy.o: file format elf32-littlearm Disassembly of section .text: 00000000 <memcpy>: 0: e92d4011 push {r0, r4, lr} 4: e2522004 subs r2, r2, #4 8: ba00002b blt bc <memcpy+0xbc> c: e210c003 ands ip, r0, #3 10: f5d1f000 pld [r1] 14: 1a000030 bne dc <memcpy+0xdc> 18: e211c003 ands ip, r1, #3 1c: 1a00003a bne 10c <memcpy+0x10c> 20: e252201c subs r2, r2, #28 24: e92d01e0 push {r5, r6, r7, r8} 28: ba00000c blt 60 <memcpy+0x60> 2c: f5d1f000 pld [r1] 30: e2522060 subs r2, r2, #96 ; 0x60 34: f5d1f01c pld [r1, #28] 38: ba000002 blt 48 <memcpy+0x48> 3c: f5d1f03c pld [r1, #60] ; 0x3c 40: f5d1f05c pld [r1, #92] ; 0x5c 44: f5d1f07c pld [r1, #124] ; 0x7c 48: e8b151f8 ldm r1!, {r3, r4, r5, r6, r7, r8, ip, lr} <------------------Load the register list from [r1] 4c: e2522020 subs r2, r2, #32 50: e8a051f8 stmia r0!, {r3, r4, r5, r6, r7, r8, ip, lr} 54: aafffffa bge 44 <memcpy+0x44> 58: e3720060 cmn r2, #96 ; 0x60 5c: aafffff9 bge 48 <memcpy+0x48> 60: e212c01c ands ip, r2, #28 64: e26cc020 rsb ip, ip, #32 68: 108ff00c addne pc, pc, ip 6c: ea000011 b b8 <memcpy+0xb8> 70: e320f000 nop {0} 74: e4913004 ldr r3, [r1], #4 78: e4914004 ldr r4, [r1], #4 7c: e4915004 ldr r5, [r1], #4 80: e4916004 ldr r6, [r1], #4 84: e4917004 ldr r7, [r1], #4 88: e4918004 ldr r8, [r1], #4 8c: e491e004 ldr lr, [r1], #4 90: e08ff00c add pc, pc, ip 94: e320f000 nop {0} 98: e320f000 nop {0} 9c: e4803004 str r3, [r0], #4 a0: e4804004 str r4, [r0], #4 a4: e4805004 str r5, [r0], #4 a8: e4806004 str r6, [r0], #4 ac: e4807004 str r7, [r0], #4 b0: e4808004 str r8, [r0], #4 b4: e480e004 str lr, [r0], #4 b8: e8bd01e0 pop {r5, r6, r7, r8} bc: e1b02f82 lsls r2, r2, #31 c0: 14d13001 ldrbne r3, [r1], #1 c4: 24d14001 ldrbcs r4, [r1], #1 c8: 24d1c001 ldrbcs ip, [r1], #1 cc: 14c03001 strbne r3, [r0], #1 d0: 24c04001 strbcs r4, [r0], #1 d4: 24c0c001 strbcs ip, [r0], #1 d8: e8bd8011 pop {r0, r4, pc} dc: e26cc004 rsb ip, ip, #4 e0: e35c0002 cmp ip, #2 e4: c4d13001 ldrbgt r3, [r1], #1 e8: a4d14001 ldrbge r4, [r1], #1 ec: e4d1e001 ldrb lr, [r1], #1 f0: c4c03001 strbgt r3, [r0], #1 f4: a4c04001 strbge r4, [r0], #1 f8: e052200c subs r2, r2, ip fc: e4c0e001 strb lr, [r0], #1 100: baffffed blt bc <memcpy+0xbc> 104: e211c003 ands ip, r1, #3 108: 0affffc4 beq 20 <memcpy+0x20> 10c: e3c11003 bic r1, r1, #3 110: e35c0002 cmp ip, #2 114: e491e004 ldr lr, [r1], #4 118: 0a00002c beq 1d0 <memcpy+0x1d0> 11c: ca000057 bgt 280 <memcpy+0x280> 120: e252201c subs r2, r2, #28 124: ba00001f blt 1a8 <memcpy+0x1a8> 128: e92d03e0 push {r5, r6, r7, r8, r9} 12c: f5d1f000 pld [r1] 130: e2522060 subs r2, r2, #96 ; 0x60 134: f5d1f01c pld [r1, #28] 138: ba000002 blt 148 <memcpy+0x148> 13c: f5d1f03c pld [r1, #60] ; 0x3c 140: f5d1f05c pld [r1, #92] ; 0x5c 144: f5d1f07c pld [r1, #124] ; 0x7c 148: e8b100f0 ldm r1!, {r4, r5, r6, r7} <------------------Load the register list from [r1] 14c: e1a0342e lsr r3, lr, #8 150: e2522020 subs r2, r2, #32 154: e8b15300 ldm r1!, {r8, r9, ip, lr} <------------------Load the register list from [r1] 158: e1833c04 orr r3, r3, r4, lsl #24 15c: e1a04424 lsr r4, r4, #8 160: e1844c05 orr r4, r4, r5, lsl #24 164: e1a05425 lsr r5, r5, #8 168: e1855c06 orr r5, r5, r6, lsl #24 16c: e1a06426 lsr r6, r6, #8 170: e1866c07 orr r6, r6, r7, lsl #24 174: e1a07427 lsr r7, r7, #8 178: e1877c08 orr r7, r7, r8, lsl #24 17c: e1a08428 lsr r8, r8, #8 180: e1888c09 orr r8, r8, r9, lsl #24 184: e1a09429 lsr r9, r9, #8 188: e1899c0c orr r9, r9, ip, lsl #24 18c: e1a0c42c lsr ip, ip, #8 190: e18ccc0e orr ip, ip, lr, lsl #24 194: e8a013f8 stmia r0!, {r3, r4, r5, r6, r7, r8, r9, ip} 198: aaffffe9 bge 144 <memcpy+0x144> 19c: e3720060 cmn r2, #96 ; 0x60 1a0: aaffffe8 bge 148 <memcpy+0x148> 1a4: e8bd03e0 pop {r5, r6, r7, r8, r9} 1a8: e212c01c ands ip, r2, #28 1ac: 0a000005 beq 1c8 <memcpy+0x1c8> 1b0: e1a0342e lsr r3, lr, #8 1b4: e491e004 ldr lr, [r1], #4 1b8: e25cc004 subs ip, ip, #4 1bc: e1833c0e orr r3, r3, lr, lsl #24 1c0: e4803004 str r3, [r0], #4 1c4: cafffff9 bgt 1b0 <memcpy+0x1b0> 1c8: e2411003 sub r1, r1, #3 1cc: eaffffba b bc <memcpy+0xbc> 1d0: e252201c subs r2, r2, #28 1d4: ba00001f blt 258 <memcpy+0x258> 1d8: e92d03e0 push {r5, r6, r7, r8, r9} 1dc: f5d1f000 pld [r1] 1e0: e2522060 subs r2, r2, #96 ; 0x60 1e4: f5d1f01c pld [r1, #28] 1e8: ba000002 blt 1f8 <memcpy+0x1f8> 1ec: f5d1f03c pld [r1, #60] ; 0x3c 1f0: f5d1f05c pld [r1, #92] ; 0x5c 1f4: f5d1f07c pld [r1, #124] ; 0x7c 1f8: e8b100f0 ldm r1!, {r4, r5, r6, r7} <------------------Load the register list from [r1] 1fc: e1a0382e lsr r3, lr, #16 200: e2522020 subs r2, r2, #32 204: e8b15300 ldm r1!, {r8, r9, ip, lr} 208: e1833804 orr r3, r3, r4, lsl #16 20c: e1a04824 lsr r4, r4, #16 210: e1844805 orr r4, r4, r5, lsl #16 214: e1a05825 lsr r5, r5, #16 218: e1855806 orr r5, r5, r6, lsl #16 21c: e1a06826 lsr r6, r6, #16 220: e1866807 orr r6, r6, r7, lsl #16 224: e1a07827 lsr r7, r7, #16 228: e1877808 orr r7, r7, r8, lsl #16 22c: e1a08828 lsr r8, r8, #16 230: e1888809 orr r8, r8, r9, lsl #16 234: e1a09829 lsr r9, r9, #16 238: e189980c orr r9, r9, ip, lsl #16 23c: e1a0c82c lsr ip, ip, #16 240: e18cc80e orr ip, ip, lr, lsl #16 244: e8a013f8 stmia r0!, {r3, r4, r5, r6, r7, r8, r9, ip} 248: aaffffe9 bge 1f4 <memcpy+0x1f4> 24c: e3720060 cmn r2, #96 ; 0x60 250: aaffffe8 bge 1f8 <memcpy+0x1f8> 254: e8bd03e0 pop {r5, r6, r7, r8, r9} 258: e212c01c ands ip, r2, #28 25c: 0a000005 beq 278 <memcpy+0x278> 260: e1a0382e lsr r3, lr, #16 264: e491e004 ldr lr, [r1], #4 268: e25cc004 subs ip, ip, #4 26c: e183380e orr r3, r3, lr, lsl #16 270: e4803004 str r3, [r0], #4 274: cafffff9 bgt 260 <memcpy+0x260> 278: e2411002 sub r1, r1, #2 27c: eaffff8e b bc <memcpy+0xbc> 280: e252201c subs r2, r2, #28 284: ba00001f blt 308 <memcpy+0x308> 288: e92d03e0 push {r5, r6, r7, r8, r9} 28c: f5d1f000 pld [r1] 290: e2522060 subs r2, r2, #96 ; 0x60 294: f5d1f01c pld [r1, #28] 298: ba000002 blt 2a8 <memcpy+0x2a8> 29c: f5d1f03c pld [r1, #60] ; 0x3c 2a0: f5d1f05c pld [r1, #92] ; 0x5c 2a4: f5d1f07c pld [r1, #124] ; 0x7c 2a8: e8b100f0 ldm r1!, {r4, r5, r6, r7} 2ac: e1a03c2e lsr r3, lr, #24 2b0: e2522020 subs r2, r2, #32 2b4: e8b15300 ldm r1!, {r8, r9, ip, lr} 2b8: e1833404 orr r3, r3, r4, lsl #8 2bc: e1a04c24 lsr r4, r4, #24 2c0: e1844405 orr r4, r4, r5, lsl #8 2c4: e1a05c25 lsr r5, r5, #24 2c8: e1855406 orr r5, r5, r6, lsl #8 2cc: e1a06c26 lsr r6, r6, #24 2d0: e1866407 orr r6, r6, r7, lsl #8 2d4: e1a07c27 lsr r7, r7, #24 2d8: e1877408 orr r7, r7, r8, lsl #8 2dc: e1a08c28 lsr r8, r8, #24 2e0: e1888409 orr r8, r8, r9, lsl #8 2e4: e1a09c29 lsr r9, r9, #24 2e8: e189940c orr r9, r9, ip, lsl #8 2ec: e1a0cc2c lsr ip, ip, #24 2f0: e18cc40e orr ip, ip, lr, lsl #8 2f4: e8a013f8 stmia r0!, {r3, r4, r5, r6, r7, r8, r9, ip} 2f8: aaffffe9 bge 2a4 <memcpy+0x2a4> 2fc: e3720060 cmn r2, #96 ; 0x60 300: aaffffe8 bge 2a8 <memcpy+0x2a8> 304: e8bd03e0 pop {r5, r6, r7, r8, r9} 308: e212c01c ands ip, r2, #28 30c: 0a000005 beq 328 <memcpy+0x328> 310: e1a03c2e lsr r3, lr, #24 314: e491e004 ldr lr, [r1], #4 318: e25cc004 subs ip, ip, #4 31c: e183340e orr r3, r3, lr, lsl #8 320: e4803004 str r3, [r0], #4 324: cafffff9 bgt 310 <memcpy+0x310> 328: e2411001 sub r1, r1, #1 32c: eaffff62 b bc <memcpy+0xbc> -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. 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