[PATCH 1/3] usb: dwc2: Fix HCD resume

[Stefan Wahren]

The Raspberry Pi can suffer on interrupt storms on HCD resume. The dwc2
driver sometimes misses to enable HCD_FLAG_HW_ACCESSIBLE before re-enabling
the interrupts. This causes a situation where both handler ignore a incoming
port interrupt and force the upper layers to disable the dwc2 interrupt
line. This leaves the USB interface in a unusable state:

irq 66: nobody cared (try booting with the "irqpoll" option)
CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W          6.10.0-rc3
Hardware name: BCM2835
Call trace:
unwind_backtrace from show_stack+0x10/0x14
show_stack from dump_stack_lvl+0x50/0x64
dump_stack_lvl from __report_bad_irq+0x38/0xc0
__report_bad_irq from note_interrupt+0x2ac/0x2f4
note_interrupt from handle_irq_event+0x88/0x8c
handle_irq_event from handle_level_irq+0xb4/0x1ac
handle_level_irq from generic_handle_domain_irq+0x24/0x34
generic_handle_domain_irq from bcm2836_chained_handle_irq+0x24/0x28
bcm2836_chained_handle_irq from generic_handle_domain_irq+0x24/0x34
generic_handle_domain_irq from generic_handle_arch_irq+0x34/0x44
generic_handle_arch_irq from __irq_svc+0x88/0xb0
Exception stack(0xc1b01f20 to 0xc1b01f68)
1f20: 0005c0d4 00000001 00000000 00000000 c1b09780 c1d6b32c c1b04e54 c1a5eae8
1f40: c1b04e90 00000000 00000000 00000000 c1d6a8a0 c1b01f70 c11d2da8 c11d4160
1f60: 60000013 ffffffff
__irq_svc from default_idle_call+0x1c/0xb0
default_idle_call from do_idle+0x21c/0x284
do_idle from cpu_startup_entry+0x28/0x2c
cpu_startup_entry from kernel_init+0x0/0x12c
handlers:
[<f539e0f4>] dwc2_handle_common_intr
[<75cd278b>] usb_hcd_irq
Disabling IRQ #66

So enable the HCD_FLAG_HW_ACCESSIBLE flag in case there is a port
connection.

Fixes: c74c26f6e398 ("usb: dwc2: Fix partial power down exiting by system resume")
Closes: https://lore.kernel.org/linux-usb/3fd0c2fb-4752-45b3-94eb-42352703e1fd@gmx.net/T/
Link: https://lore.kernel.org/all/5e8cbce0-3260-2971-484f-fc73a3b2bd28@synopsys.com/
Signed-off-by: Stefan Wahren <wahrenst at gmx.net>
---
 drivers/usb/dwc2/hcd.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index cb54390e7de4..26a320c1979a 100644
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -4431,6 +4431,7 @@ static int _dwc2_hcd_resume(struct usb_hcd *hcd)
 	 * Power Down mode.
 	 */
 	if (hprt0 & HPRT0_CONNSTS) {
+		set_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
 		hsotg->lx_state = DWC2_L0;
 		goto unlock;
 	}
--
2.34.1