And there are no multiple TRBs on EP0 and WA1 workaround, so it doesn't need to change TRB for EP0. It fixes below oops. configfs-gadget gadget: high-speed config #1: b android_work: sent uevent USB_STATE=CONFIGURED Unable to handle kernel read from unreadable memory at virtual address 0000000000000008 Mem abort info: android_work: sent uevent USB_STATE=DISCONNECTED ESR = 0x96000004 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 Data abort info: ISV = 0, ISS = 0x00000004 CM = 0, WnR = 0 user pgtable: 4k pages, 48-bit VAs, pgdp=00000008b5bb7000 [0000000000000008] pgd=0000000000000000 Internal error: Oops: 96000004 [#1] PREEMPT SMP Modules linked in: CPU: 2 PID: 430 Comm: HwBinder:401_1 Not tainted 5.4.24-06071-g6fa8921409c1-dirty #77 Hardware name: Freescale i.MX8QXP MEK (DT) pstate: 60400085 (nZCv daIf +PAN -UAO) pc : cdns3_gadget_ep_dequeue+0x1d4/0x270 lr : cdns3_gadget_ep_dequeue+0x48/0x270 sp : ffff800012763ba0 x29: ffff800012763ba0 x28: ffff00082c653c00 x27: 0000000000000000 x26: ffff000068fa7b00 x25: ffff0000699b2000 x24: ffff00082c6ac000 x23: ffff000834f0a480 x22: ffff000834e87b9c x21: 0000000000000000 x20: ffff000834e87800 x19: ffff000069eddc00 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000001 x11: ffff80001180fbe8 x10: 0000000000000001 x9 : ffff800012101558 x8 : 0000000000000001 x7 : 0000000000000006 x6 : ffff000835d9c668 x5 : ffff000834f0a4c8 x4 : 0000000096000000 x3 : 0000000000001810 x2 : 0000000000000000 x1 : ffff800024bd001c x0 : 0000000000000001 Call trace: cdns3_gadget_ep_dequeue+0x1d4/0x270 usb_ep_dequeue+0x34/0xf8 composite_dev_cleanup+0x154/0x170 configfs_composite_unbind+0x6c/0xa8 usb_gadget_remove_driver+0x44/0x70 usb_gadget_unregister_driver+0x74/0xe0 unregister_gadget+0x28/0x58 gadget_dev_desc_UDC_store+0x80/0x110 configfs_write_file+0x1e0/0x2a0 __vfs_write+0x48/0x90 vfs_write+0xe4/0x1c8 ksys_write+0x78/0x100 __arm64_sys_write+0x24/0x30 el0_svc_common.constprop.0+0x74/0x168 el0_svc_handler+0x34/0xa0 el0_svc+0x8/0xc Code: 52830203 b9407660 f94042e4 11000400 (b9400841) ---[ end trace 1574516e4c1772ca ]--- Kernel panic - not syncing: Fatal exception SMP: stopping secondary CPUs Kernel Offset: disabled CPU features: 0x0002,20002008 Memory Limit: none Rebooting in 5 seconds.. Fixes: f616c3bda47e ("usb: cdns3: Fix dequeue implementation") Cc: stable <stable@xxxxxxxxxxxxxxx> Signed-off-by: Peter Chen <peter.chen@xxxxxxx> --- drivers/usb/cdns3/gadget.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/usb/cdns3/gadget.c b/drivers/usb/cdns3/gadget.c index 996699bd312f..c6908374232a 100644 --- a/drivers/usb/cdns3/gadget.c +++ b/drivers/usb/cdns3/gadget.c @@ -2552,7 +2552,7 @@ int cdns3_gadget_ep_dequeue(struct usb_ep *ep, link_trb = priv_req->trb; /* Update ring only if removed request is on pending_req_list list */ - if (req_on_hw_ring) { + if (req_on_hw_ring && link_trb) { link_trb->buffer = TRB_BUFFER(priv_ep->trb_pool_dma + ((priv_req->end_trb + 1) * TRB_SIZE)); link_trb->control = (link_trb->control & TRB_CYCLE) | -- 2.17.1