6.12-stable review patch. If anyone has any objections, please let me know.
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From: Mathias Nyman mathias.nyman@linux.intel.com
commit bea5892d0ed274e03655223d1977cf59f9aff2f2 upstream.
Current xhci bus resume implementation prevents xHC host from generating interrupts during high-speed USB 2 and super-speed USB 3 bus resume.
Only reason to disable interrupts during bus resume would be to prevent the interrupt handler from interfering with the resume process of USB 2 ports.
Host initiated resume of USB 2 ports is done in two stages.
The xhci driver first transitions the port from 'U3' to 'Resume' state, then wait in Resume for 20ms, and finally moves port to U0 state. xhci driver can't prevent interrupts by keeping the xhci spinlock due to this 20ms sleep.
Limit interrupt disabling to the USB 2 port resume case only. resuming USB 2 ports in bus resume is only done in special cases where USB 2 ports had to be forced to suspend during bus suspend.
The current way of preventing interrupts by clearing the 'Interrupt Enable' (INTE) bit in USBCMD register won't prevent the Interrupter registers 'Interrupt Pending' (IP), 'Event Handler Busy' (EHB) and USBSTS register Event Interrupt (EINT) bits from being set.
New interrupts can't be issued before those bits are properly clered.
Disable interrupts by clearing the interrupter register 'Interrupt Enable' (IE) bit instead. This way IP, EHB and INTE won't be set before IE is enabled again and a new interrupt is triggered.
Reported-by: Devyn Liu liudingyuan@huawei.com Closes: https://lore.kernel.org/linux-usb/b1a9e2d51b4d4ff7a304f77c5be8164e@huawei.co... Cc: stable@vger.kernel.org Tested-by: Devyn Liu liudingyuan@huawei.com Signed-off-by: Mathias Nyman mathias.nyman@linux.intel.com Link: https://lore.kernel.org/r/20250410151828.2868740-6-mathias.nyman@linux.intel... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/host/xhci-hub.c | 30 ++++++++++++++++-------------- drivers/usb/host/xhci.c | 4 ++-- drivers/usb/host/xhci.h | 2 ++ 3 files changed, 20 insertions(+), 16 deletions(-)
--- a/drivers/usb/host/xhci-hub.c +++ b/drivers/usb/host/xhci-hub.c @@ -1878,9 +1878,10 @@ int xhci_bus_resume(struct usb_hcd *hcd) int max_ports, port_index; int sret; u32 next_state; - u32 temp, portsc; + u32 portsc; struct xhci_hub *rhub; struct xhci_port **ports; + bool disabled_irq = false;
rhub = xhci_get_rhub(hcd); ports = rhub->ports; @@ -1896,17 +1897,20 @@ int xhci_bus_resume(struct usb_hcd *hcd) return -ESHUTDOWN; }
- /* delay the irqs */ - temp = readl(&xhci->op_regs->command); - temp &= ~CMD_EIE; - writel(temp, &xhci->op_regs->command); - /* bus specific resume for ports we suspended at bus_suspend */ - if (hcd->speed >= HCD_USB3) + if (hcd->speed >= HCD_USB3) { next_state = XDEV_U0; - else + } else { next_state = XDEV_RESUME; - + if (bus_state->bus_suspended) { + /* + * prevent port event interrupts from interfering + * with usb2 port resume process + */ + xhci_disable_interrupter(xhci->interrupters[0]); + disabled_irq = true; + } + } port_index = max_ports; while (port_index--) { portsc = readl(ports[port_index]->addr); @@ -1974,11 +1978,9 @@ int xhci_bus_resume(struct usb_hcd *hcd) (void) readl(&xhci->op_regs->command);
bus_state->next_statechange = jiffies + msecs_to_jiffies(5); - /* re-enable irqs */ - temp = readl(&xhci->op_regs->command); - temp |= CMD_EIE; - writel(temp, &xhci->op_regs->command); - temp = readl(&xhci->op_regs->command); + /* re-enable interrupter */ + if (disabled_irq) + xhci_enable_interrupter(xhci->interrupters[0]);
spin_unlock_irqrestore(&xhci->lock, flags); return 0; --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -321,7 +321,7 @@ static void xhci_zero_64b_regs(struct xh xhci_info(xhci, "Fault detected\n"); }
-static int xhci_enable_interrupter(struct xhci_interrupter *ir) +int xhci_enable_interrupter(struct xhci_interrupter *ir) { u32 iman;
@@ -334,7 +334,7 @@ static int xhci_enable_interrupter(struc return 0; }
-static int xhci_disable_interrupter(struct xhci_interrupter *ir) +int xhci_disable_interrupter(struct xhci_interrupter *ir) { u32 iman;
--- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -1881,6 +1881,8 @@ int xhci_alloc_tt_info(struct xhci_hcd * struct usb_tt *tt, gfp_t mem_flags); int xhci_set_interrupter_moderation(struct xhci_interrupter *ir, u32 imod_interval); +int xhci_enable_interrupter(struct xhci_interrupter *ir); +int xhci_disable_interrupter(struct xhci_interrupter *ir);
/* xHCI ring, segment, TRB, and TD functions */ dma_addr_t xhci_trb_virt_to_dma(struct xhci_segment *seg, union xhci_trb *trb);