usb: dwc2: Fix HCD port connection race

On Raspberry Pis without onboard USB hub frequent device reconnects
can trigger a interrupt storm after DWC2 entered host clock gating.
This is caused by a race between _dwc2_hcd_suspend() and the port
interrupt, which sets port_connect_status. The issue occurs if
port_connect_status is still 1, but there is no connection anymore:

usb 1-1: USB disconnect, device number 25
dwc2 3f980000.usb: _dwc2_hcd_suspend: port_connect_status: 1
dwc2 3f980000.usb: Entering host clock gating.
Disabling IRQ #66
irq 66: nobody cared (try booting with the "irqpoll" option)
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.12.0-gc1bb81b13202-dirty #322
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(0xc1d01f20 to 0xc1d01f68)
 1f20: 0004ef3c 00000001 00000000 00000000 c1d09780 c1f6bb5c c1d04e54 c1c60ca8
 1f40: c1d04e94 00000000 00000000 c1d092a8 c1f6af20 c1d01f70 c1211b98 c1212f40
 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:
 [<e3a25c00>] dwc2_handle_common_intr
 [<58bf98a3>] usb_hcd_irq
Disabling IRQ #66

So avoid this by reading the connection status directly.

Fixes: 113f86d ("usb: dwc2: Update partial power down entering by system suspend")
Signed-off-by: Stefan Wahren <[email protected]>

drivers/usb/dwc2/hcd.c

@@ -4345,7 +4345,7 @@ static int _dwc2_hcd_suspend(struct usb_hcd *hcd)
 	if (hsotg->bus_suspended)
 		goto skip_power_saving;
 
-	if (hsotg->flags.b.port_connect_status == 0)
+	if (!(dwc2_read_hprt0(hsotg) & HPRT0_CONNSTS))
 		goto skip_power_saving;
 
 	switch (hsotg->params.power_down) {