Hi
We have received the patch changing the way of interrupt disabling, thank you very much!
Over the past couple of days, we have also conducted tests using the modified kernel in the problematic scenarios.
I believe that this patch can resolve the issue and avoid some potential interrupt loss problems. Thank you once again!
We plan to conduct further testing on some basic USB functionalities based on the latest Linux kernel and our kernel in the coming period
(including read/write operations with USB drives or hard disks, multi-level devices, and basic read/write stress tests, etc.).
The testing is expected to take approximately two weeks to complete. We will finish the further verification process and provide you with feedback
about the results as soon as possible.
During this period, we may also engage in further discussions with hardware personnel to ensure that the hardware implementation aligns with expectations.
Thanks.
Best regards!
Devyn
>
> [RFT PATCH] xhci: Limit time spent with interrupts disabled during bus resume
>
> 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 taking and keeping the xhci spinlock with spin_lock_irqsave() 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.
>
> This way IP, EHB and INTE won't be set before IE is enabled again and a new interrupt is triggered.
>
> Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
> ---
> 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(-)
>
> diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c index 9693464c0520..d11b60f705bb 100644
> --- a/drivers/usb/host/xhci-hub.c
> +++ b/drivers/usb/host/xhci-hub.c
> @@ -1870,9 +1870,10 @@ 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;
> @@ -1888,17 +1889,20 @@ 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); @@ -1966,11 +1970,9 @@ 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;
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index 0c22b78358b9..ad229cb9a90b 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -322,7 +322,7 @@ static void xhci_zero_64b_regs(struct xhci_hcd *xhci)
> 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;
>
> @@ -335,7 +335,7 @@ static int xhci_enable_interrupter(struct xhci_interrupter *ir)
> return 0;
> }
>
> -static int xhci_disable_interrupter(struct xhci_interrupter *ir)
> +int xhci_disable_interrupter(struct xhci_interrupter *ir)
> {
> u32 iman;
>
> diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h index 6c00062a9acc..10572336fabe 100644
> --- a/drivers/usb/host/xhci.h
> +++ b/drivers/usb/host/xhci.h
> @@ -1891,6 +1891,8 @@ int xhci_alloc_tt_info(struct xhci_hcd *xhci,
> 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);
> --
> 2.43.0
