We are experiencing problems with the USB port on iPad Pro 11 inch (M4) model number MVW13NF/A. Our custom peripheral device (based on Raspberry Pi Pico + tinyUSB stack, is configured as a network adapter class and has communication with our App over UDP protocol. Our device also acts as a DHCP server, providing the IP address for iPad.
The problem can be described as a “bus stall” or "bus hold" after sleep mode. To reproduce it we just send the iPad into sleep mode using a power button, the USB bus on M4 goes to the suspended state and won’t resume anymore when we wake the iPad up.
The problem has occurred since the upgrade to iOS 18.2.1 and has not been observed before on the previously installed iOS 17 on the same iPad Pro M4.
Also, the problem does not happen on the iPad Pro 11 inch (3rd gen with M1) model number MHW73FD/A, with the same iOS 18.2.1 installed. The problem also does not arise, if we connect our device via USB hub to the same iPad Pro M4.
We have tested different versions of tinyUSB stack (either included in RPi Pico SDK or native unpatched). The problem is independent of the library version. It occurs always if our device is connected directly to the USB port of iPad Pro (M4) with iOS 18. It also stays after upgrading to the latest iOS 18.3 (beta)
In the attached logs is (reduced for clarity) debug output from tinyUSB library about events on the USB bus. These logs were captured via RTT debugging output, using Segger J-Link debugger, so logging process does not affect the timings on the USB bus.
There are three logs attached, for cases 1: "iPad Pro M4 + iOS18" (i.e. problematic case), 2: "iPad Pro M1 + iOS18", and 3: "iPad Pro M4 + iOS18 + external USB hub" (they are non-problematic cases).
CASE 1: USB communications on the bus (iPadPro M4 + iOS 18.3), until the bus stalled. 00> USBD Setup Received 00 05 02 00 00 00 00 00 00> Set Address 00> Prepare BufCtrl: [0] = 0xf400 [1] = 0x0000 00> buf_status = 0x00000001 00> Sync BufCtrl: [0] = 0x6000 [1] = 0x0000 00> Short packet on buffer 0 with 0 bytes 00> Completed transfer of 0 bytes on ep 80 00> USBD Xfer Complete on EP 80 with 0 bytes 00> 00> USBD Setup Received 80 06 00 01 00 00 08 00 00> Get Descriptor Device 00> Queue EP 80 with 8 bytes ... 00> Prepare BufCtrl: [0] = 0xf408 [1] = 0x0000 00> buf_status = 0x00000001 00> Sync BufCtrl: [0] = 0x6008 [1] = 0x0000 00> Short packet on buffer 0 with 8 bytes 00> Completed transfer of 8 bytes on ep 80 00> USBD Xfer Complete on EP 80 with 8 bytes 00> Queue EP 00 with 0 bytes ... 00> Prepare BufCtrl: [0] = 0x7400 [1] = 0x0000 00> buf_status = 0x00000002 00> Sync BufCtrl: [0] = 0xe000 [1] = 0x0000 00> Short packet on buffer 0 with 0 bytes 00> Completed transfer of 0 bytes on ep 00 00> USBD Xfer Complete on EP 00 with 0 bytes 00> 00> USBD Setup Received 80 06 00 01 00 00 12 00 00> Device 00> 00> 00> Queue EP 82 with 42 bytes ... 00> Prepare BufCtrl: [0] = 0xf42a [1] = 0x0000 00> buf_status = 0x00000010 00> Sync BufCtrl: [0] = 0x602a [1] = 0x0000 00> Short packet on buffer 0 with 42 bytes 00> Completed transfer of 42 bytes on ep 82 00> USBD Xfer Complete buf_status = 0x00000020 00> Sync BufCtrl: [0] = 0xa02a [1] = 0x0000 00> Short packet on buffer 0 with 42 bytes 00> Completed transfer of 42 bytes on ep 02 00> on EP 82 with 42 bytes 00> NET xfer callback <----CUTOUT-FOR-REGULAR-TRAFFIC-ON-THE-BUS-----------------> 00> NET xfer callback 00> USBD Xfer Complete on EP 80 with 0 bytes 00> buf_status = 0x00000004 00> Sync BufCtrl: [0] = 0x4008 [1] = 0x0000 00> Short packet on buffer 0 with 8 bytes 00> Completed transfer of 8 bytes on ep 81 00> USBD Xfer Complete on EP 81 with 8 bytes 00> NET xfer callback 00> Queue EP 81 with 16 bytes ... 00> Prepare BufCtrl: [0] = 0xf410 [1] = 0x0000 5 SECONDS AFTER ENTER INTO SLEEP MODE! (M4 iPad + iOS 18) 00> USBD Suspend : Remote Wakeup = 0 00> BUS RESET 00> USBD Bus Reset: Full Speed SINCE THIS MOMENT THE USB BUS STALLS!
CASE 2: SAME TEST BUT FOR M1 iPadPro + iOS18.2.1
START of INIT
00> USBD Setup Received 00 05 01 00 00 00 00 00
00> Set Address
00> Prepare BufCtrl: [0] = 0xf400 [1] = 0x0000
00> buf_status = 0x00000001
00> Sync BufCtrl: [0] = 0x6000 [1] = 0x0000
00> Short packet on buffer 0 with 0 bytes
00> Completed transfer of 0 bytes on ep 80
00> USBD Xfer Complete on EP 80 with 0 bytes
00> USBD Setup Received 00 09 02 00 00 00 00 00
00> Set Configuration
00> Open EP 81 with Size = 64
00> Allocated 64 bytes at offset 0x180 (0x50100180)
00> NET opened
00> Bind EP 81 to driver id 0
00> Bind EP 82 to driver id 0
00> Bind EP 02 to driver id 0
00> Queue EP 80 with 0 bytes ...
00> Prepare BufCtrl: [0] = 0xf400 [1] = 0x0000
00> buf_status = 0x00000001
00> Sync BufCtrl: [0] = 0x6000 [1] = 0x0000
00> Short packet on buffer 0 with 0 bytes
00> Completed transfer of 0 bytes on ep 80
00> USBD Xfer Complete on EP 80 with 0 bytes
00>
00> USBD Setup Received 80 06 04 03 09 04 02 00
00> Get Descriptor String[4]
00> Queue EP 80 with 2 bytes ...
00> Prepare BufCtrl: [0] = 0xf402 [1] = 0x0000
00> buf_status = 0x00000001
00> Sync BufCtrl: [0] = 0x6002 [1] = 0x0000
00> Short packet on buffer 0 with 2 bytes
00> Completed transfer of 2 bytes on ep 80
00> USBD Xfer Complete on EP 80 with 2 bytes
00> Queue EP 00 with 0 bytes ...
00> Prepare BufCtrl: [0] = 0x7400 [1] = 0x0000
00> buf_status = 0x00000002
00> Sync BufCtrl: [0] = 0xe000 [1] = 0x0000
00> Short packet on buffer 0 with 0 bytes
00> Completed transfer of 0 bytes on ep 00
00> USBD Xfer Complete on EP 00 with 0 bytes
00>
00> USBD Setup Received 80 06 04 03 09 04 34 00
00> Get Descriptor String[4]
00> Queue EP 80 with 52 bytes ...
00> Prepare BufCtrl: [0] = 0xf434 [1] = 0x0000
00> buf_status = 0x00000001
00> Sync BufCtrl: [0] = 0x6034 [1] = 0x0000
00> Short packet on buffer 0 with 52 bytes
00> Completed transfer of 52 bytes on ep 80
00> USBD Xfer Complete on EP 80 with 52 bytes
00> Queue EP 00 with 0 bytes ...
00> Prepare BufCtrl: [0] = 0x7400 [1] = 0x0000
00> buf_status = 0x00000002
00> Sync BufCtrl: [0] = 0xe000 [1] = 0x0000
00> Short packet on buffer 0 with 0 bytes
00> Completed transfer of 0 bytes on ep 00
00> USBD Xfer Complete on EP 00 with 0 bytes
00>
00> USBD Setup Received 01 0B 00 00 01 00 00 00
00> Set Interface
00> NET control request
00> Queue EP 80 with 0 bytes ...
00> Prepare BufCtrl: [0] = 0xf400 [1] = 0x0000
00> buf_status = 0x00000001
00> Sync BufCtrl: [0] = 0x6000 [1] = 0x0000
00> Short packet on buffer 0 with 0 bytes
00> Completed transfer of 0 bytes on ep 80
00> USBD Xfer Complete on EP 80 with 0 bytes
00>
00> USBD Setup Received 01 0B 01 00 01 00 00 00
00> Set Interface
00> NET control request
00> Open EP 82 with Size = 64
00> Allocated 128 bytes at offset 0x1c0 (0x501001C0)
00> Open EP 02 with Size = 64
00> Allocated 128 bytes at offset 0x240 (0x50100240)
00> Queue EP 02 with 1602 bytes ...
00> Prepare BufCtrl: [0] = 0x1440 [1] = 0x0000
00> Queue EP 80 with 0 bytes ...
00> Prepare BufCtrl: [0] = 0xf400 [1] = 0x0000
00> buf_status = 0x00000001
00> Sync BufCtrl: [0] = 0x6000 [1] = 0x0000
00> Short packet on buffer 0 with 0 bytes
00> Completed transfer of 0 bytes on ep 80
00> USBD Xfer Complete on EP 80 with 0 bytes
00>
00> USBD Setup Received 21 43 00 00 00 00 00 00
00> NET control request
00> Queue EP 80 with 0 bytes ...
00> Prepare BufCtrl: [0] = 0xf400 [1] = 0x0000
00> Queue EP 81 with 8 bytes ...
00> Prepare BufCtrl: [0] = 0xd408 [1] = 0x0000
00> buf_status = 0x00000001
00> Sync BufCtrl: [0] = 0x6000 [1] = 0x0000
00> Short packet on buffer 0 with 0 bytes
00> Completed transfer of 0 bytes on ep 80
00> USBD Xfer Complete on EP 80 with 0 bytes
00>
00> USBD Setup Received 80 06 05 03 09 04 02 00
00> Get Descriptor String[5]
00> Queue EP 80 with 2 bytes ...
00> Prepare BufCtrl: [0] = 0xf402 [1] = 0x0000
00> buf_status = 0x00000001
00> Sync BufCtrl: [0] = 0x6002 [1] = 0x0000
00> Short packet on buffer 0 with 2 bytes
00> Completed transfer of 2 bytes on ep 80
00> buf_status = 0x00000010
00> Sync BufCtrl: [0] = 0x0040 [1] = 0x2040
00> Prepare BufCtrl: [0] = 0x9440 [1] = 0xa440
00> buf_status = 0x00000010
00> Sync BufCtrl: [0] = 0x0040 [1] = 0x2040
00> Prepare BufCtrl: [0] = 0xd42e [1] = 0x0000
00> USBD Xfer Complete buf_status = 0x00000010
00> Sync BufCtrl: [0] = 0x402e [1] = 0x0000
00> Short packet on buffer 0 with 46 bytes
00> Completed transfer of 558 bytes on ep 82
00> on EP 02 with 62 bytes
00> NET xfer callback
00> USBD Xfer Complete buf_status = 0x00000004
00> Sync BufCtrl: [0] = 0x6010 [1] = 0x0000
00> Short packet on buffer 0 with 16 bytes
00> Completed transfer of 16 bytes on ep 81
00> USBD Xfer Complete on EP 81 with 16 bytes
00> NET xfer callback
<----CUTOUT-OF-REGULAR-TRAFFIC-ON-THE-BUS----------------->
00> Completed transfer of 8 bytes on ep 81
00> USBD Xfer Complete on EP 81 with 8 bytes
00> NET xfer callback
00> Queue EP 81 with 16 bytes ...
00> Prepare BufCtrl: [0] = 0xf410 [1] = 0x0000
ON M1 iPAD � WENT ONTO SLEEP MODE
00> USBD Suspend : Remote Wakeup = 0
NO BUS RESET! THEN, THE CORRECT WAKE-UP WAS PERFORMED AND DEVICE FUNCTIONS WERE RESTORED
00> Queue EP 82 with 42 bytes ...
00> Prepare BufCtrl: [0] = 0xd42a [1] = 0x0000
00> USBD Resume
Correct resuming of the bus.
00> buf_status = 0x00000010
00> Sync BufCtrl: [0] = 0x402a [1] = 0x0000
00> Short packet on buffer 0 with 42 bytes
00> Completed transfer of 42 bytes on ep 82
00> USBD Xfer Complete on EP 82 with 42 bytes
00> NET xfer callback
00>
00> USBD Setup Received 21 43 0E 00 00 00 00 00
00> NET control request
00> Queue EP 80 with 0 bytes ...
00> Prepare BufCtrl: [0] = 0xf400 [1] = 0x0000
00> buf_status = 0x00000001
CASE 3 : The iPad Pro is the same M4-based model as in case 1 + USB HUB. Our device connected via a USB hub. 00> USBD Setup Received 00 05 06 00 00 00 00 00 00> Set Address 00> Prepare BufCtrl: [0] = 0xf400 [1] = 0x0000 00> buf_status = 0x00000001 00> Sync BufCtrl: [0] = 0x6000 [1] = 0x0000 00> Short packet on buffer 0 with 0 bytes 00> Completed transfer of 0 bytes on ep 80 00> USBD Xfer Complete on EP 80 with 0 bytes 00> 00> USBD Setup Received 80 06 00 01 00 00 08 00 00> Get Descriptor Device 00> Queue EP 80 with 8 bytes ... 00> Prepare BufCtrl: [0] = 0xf408 [1] = 0x0000 00> buf_status = 0x00000001 00> Sync BufCtrl: [0] = 0x6008 [1] = 0x0000 00> Short packet on buffer 0 with 8 bytes 00> Completed transfer of 8 bytes on ep 80 00> USBD Xfer Complete on EP 80 with 8 bytes 00> Queue EP 00 with 0 bytes ... 00> Prepare BufCtrl: [0] = 0x7400 [1] = 0x0000 00> buf_status = 0x00000002 00> Sync BufCtrl: [0] = 0xe000 [1] = 0x0000 00> Short packet on buffer 0 with 0 bytes 00> Completed transfer of 0 bytes on ep 00 00> USBD Xfer Complete on EP 00 with 0 bytes 00> 00> USBD Setup Received 80 06 00 01 00 00 12 00 00> 00> 00> buf_status = 0x00000020 00> Sync BufCtrl: [0] = 0xa040 [1] = 0x0000 00> Prepare BufCtrl: [0] = 0x1440 [1] = 0x0000 00> buf_status = 0x00000020 00> Sync BufCtrl: [0] = 0x8040 [1] = 0x0000 00> Prepare BufCtrl: [0] = 0x3440 [1] = 0x0000 00> buf_status = 0x00000020 00> Sync BufCtrl: [0] = 0xa010 [1] = 0x0000 00> Short packet on buffer 0 with 16 bytes 00> Completed transfer of 144 bytes on ep 02 00> Queue EP 82 with 42 bytes ... 00> Prepare BufCtrl: [0] = 0xf42a [1] = 0x0000 00> USBD Xfer Complete on EP 02 with 144 bytes 00> buf_status = 0x00000010 00> Sync BufCtrl: [0] = 0x602a [1] = 0x0000 00> Short packet on buffer 0 with 42 bytes 00> Completed transfer of 42 bytes on ep 82 00> NET xfer callback <----CUTOUT-FOR-REGULAR-TRAFFIC-ON-THE-BUS-----------------> 00> NET xfer callback 00> USBD Xfer Complete on EP 80 with 0 bytes 00> buf_status = 0x00000004 00> Sync BufCtrl: [0] = 0x4008 [1] = 0x0000 00> Short packet on buffer 0 with 8 bytes 00> Completed transfer of 8 bytes on ep 81 00> USBD Xfer Complete on EP 81 with 8 bytes 00> NET xfer callback 00> Queue EP 81 with 16 bytes ... 00> Prepare BufCtrl: [0] = 0xf410 [1] = 0x0000 WENT INTO SLEEP MODE on M4 + HUB. 00> USBD Suspend : Remote Wakeup = 0 00> Queue EP 82 with 42 bytes ... 00> Prepare BufCtrl: [0] = 0xd42a [1] = 0x0000 00> USBD Resume And the bus woke up, as expected 00> buf_status = 0x00000010 00> Sync BufCtrl: [0] = 0x402a [1] = 0x0000 00> Short packet on buffer 0 with 42 bytes 00> Completed transfer of 42 bytes on ep 82 00> USBD Xfer Complete on EP 82 with 42 bytes 00> NET xfer callback 00> 00> USBD Setup Received 21 43 0E 00 00 00 00 00 00> NET control request 00> Queue EP 80 with 0 bytes ... 00> Prepare BufCtrl: [0] = 0xf400 [1] = 0x0000 00> buf_status = 0x00000001 00> Sync BufCtrl: [0] = 0x6000 [1] = 0x0000 00> Short packet on buffer 0 with 0 bytes 00> Completed transfer of 0 bytes on ep 80 00> USBD Xfer Complete on EP 80 with 0 bytes 00> 00> USBD Setup Received 21 43 0E 00 00 00 00 00 00> NET control request 00> Queue EP 80 with 0 bytes ... 00> buf_status = 0x00000004 00> Sync BufCtrl: [0] = 0x6010 [1] = 0x0000 00> Short packet on buffer 0 with 16 bytes 00> Completed transfer of 16 bytes on ep 81 00> Prepare BufCtrl: [0] = 0xf400 [1] = 0x0000 00> buf_status = 0x00000001 00> Sync BufCtrl: [0] = 0x6000 [1] = 0x0000 00> Short packet on buffer 0 with 0 bytes 00> Completed transfer of 0 bytes on ep 80 00> buf_status = 0x00000020 00> Sync BufCtrl: [0] = 0xa02a [1] = 0x0000 00> Short packet on buffer 0 with 42 bytes 00> Completed transfer of 42 bytes on ep 02 00> USBD Xfer Complete 00> 21 43 0E 00> Short packet on buffer 0 with 0 bytes 00> Completed transfer of 0 bytes on ep 80 00> buf_status = 0x00000020 00> Sync BufCtrl: [0] = 0x8040 [1] = 0x0000 00> Prepare BufCtrl: [0] = 0x3440 [1] = 0x0000 00> buf_status = 0x00000020 00> Sync BufCtrl: [0] = 0xa040 [1] = 0x0000 00> Prepare BufCtrl: [0] = 0x1440 [1] = 0x0000 00> Queue EP 81 with 8 bytes ... 00> buf_status = 0x00000020 00> Sync BufCtrl: [0] = 0x8040 [1] = 0x0000 00> buf_status = 0x00000020 00> USBD Xfer Complete Prepare BufCtrl: [0] = 0xf42e [1] = 0x0000 00> buf_status = 0x00000010 00> Sync BufCtrl: [0] = 0x602e [1] = 0x0000 00> Short packet on buffer 0 with 46 bytes 00> Completed transfer of 558 bytes on ep 82 00> USBD Xfer Complete on EP 82 with 558 bytes 00> NET xfer callback 00> buf_status = 0x00000004 00> Sync BufCtrl: [0] = 0x4008 [1] = 0x0000 00> Short packet on buffer 0 with 8 bytes 00> Completed transfer of 8 bytes on ep 81 00> USBD Xfer Complete on EP 81 with 8 bytes 00> NET xfer callback So, on the same iPad but with the external USB Hub communications we can observe the correct behavior of the USB bus in sleep mode.
This was already posted as feedback with id FB16366509
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