Re: [PATCH v36 02/31] usb: host: xhci-mem: Cleanup pending secondary event ring events

[Jung Daehwan <dh10.jung@samsung.com>]

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On Fri, Mar 28, 2025 at 03:42:00PM +0800, Puma Hsu wrote:
> On Wed, Mar 19, 2025 at 8:53 AM Wesley Cheng <quic_wcheng@quicinc.com> wrote:
> >
> > As part of xHCI bus suspend, the xHCI is halted.  However, if there are
> > pending events in the secondary event ring, it is observed that the xHCI
> > controller stops responding to further commands upon host or device
> > initiated bus resume.  Iterate through all pending events and update the
> > dequeue pointer to the beginning of the event ring.
> >
> > Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
> 
> Tested-by: Puma Hsu <pumahsu@google.com>
> 

 Tested-by: Daehwan Jung <dh10.jung@samsung.com>

> > ---
> >  drivers/usb/host/xhci-mem.c  |  7 +++++-
> >  drivers/usb/host/xhci-ring.c | 47 ++++++++++++++++++++++++++++++------
> >  drivers/usb/host/xhci.c      |  2 +-
> >  drivers/usb/host/xhci.h      |  7 ++++++
> >  4 files changed, 54 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
> > index d698095fc88d..daea0f76e844 100644
> > --- a/drivers/usb/host/xhci-mem.c
> > +++ b/drivers/usb/host/xhci-mem.c
> > @@ -1805,7 +1805,7 @@ xhci_remove_interrupter(struct xhci_hcd *xhci, struct xhci_interrupter *ir)
> >                 tmp &= ERST_SIZE_MASK;
> >                 writel(tmp, &ir->ir_set->erst_size);
> >
> > -               xhci_write_64(xhci, ERST_EHB, &ir->ir_set->erst_dequeue);
> > +               xhci_update_erst_dequeue(xhci, ir, true);
> >         }
> >  }
> >
> > @@ -1848,6 +1848,11 @@ void xhci_remove_secondary_interrupter(struct usb_hcd *hcd, struct xhci_interrup
> >                 return;
> >         }
> >
> > +       /*
> > +        * Cleanup secondary interrupter to ensure there are no pending events.
> > +        * This also updates event ring dequeue pointer back to the start.
> > +        */
> > +       xhci_skip_sec_intr_events(xhci, ir->event_ring, ir);
> >         intr_num = ir->intr_num;
> >
> >         xhci_remove_interrupter(xhci, ir);
> > diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
> > index 5d64c297721c..bfef765dd78c 100644
> > --- a/drivers/usb/host/xhci-ring.c
> > +++ b/drivers/usb/host/xhci-ring.c
> > @@ -3054,9 +3054,9 @@ static int xhci_handle_event_trb(struct xhci_hcd *xhci, struct xhci_interrupter
> >   * - When all events have finished
> >   * - To avoid "Event Ring Full Error" condition
> >   */
> > -static void xhci_update_erst_dequeue(struct xhci_hcd *xhci,
> > -                                    struct xhci_interrupter *ir,
> > -                                    bool clear_ehb)
> > +void xhci_update_erst_dequeue(struct xhci_hcd *xhci,
> > +                             struct xhci_interrupter *ir,
> > +                             bool clear_ehb)
> >  {
> >         u64 temp_64;
> >         dma_addr_t deq;
> > @@ -3099,10 +3099,11 @@ static void xhci_clear_interrupt_pending(struct xhci_interrupter *ir)
> >   * Handle all OS-owned events on an interrupter event ring. It may drop
> >   * and reaquire xhci->lock between event processing.
> >   */
> > -static int xhci_handle_events(struct xhci_hcd *xhci, struct xhci_interrupter *ir)
> > +static int xhci_handle_events(struct xhci_hcd *xhci, struct xhci_interrupter *ir,
> > +                             bool skip_events)
> >  {
> >         int event_loop = 0;
> > -       int err;
> > +       int err = 0;
> >         u64 temp;
> >
> >         xhci_clear_interrupt_pending(ir);
> > @@ -3125,7 +3126,8 @@ static int xhci_handle_events(struct xhci_hcd *xhci, struct xhci_interrupter *ir
> >
> >         /* Process all OS owned event TRBs on this event ring */
> >         while (unhandled_event_trb(ir->event_ring)) {
> > -               err = xhci_handle_event_trb(xhci, ir, ir->event_ring->dequeue);
> > +               if (!skip_events)
> > +                       err = xhci_handle_event_trb(xhci, ir, ir->event_ring->dequeue);
> >
> >                 /*
> >                  * If half a segment of events have been handled in one go then
> > @@ -3152,6 +3154,37 @@ static int xhci_handle_events(struct xhci_hcd *xhci, struct xhci_interrupter *ir
> >         return 0;
> >  }
> >
> > +/*
> > + * Move the event ring dequeue pointer to skip events kept in the secondary
> > + * event ring.  This is used to ensure that pending events in the ring are
> > + * acknowledged, so the xHCI HCD can properly enter suspend/resume.  The
> > + * secondary ring is typically maintained by an external component.
> > + */
> > +void xhci_skip_sec_intr_events(struct xhci_hcd *xhci,
> > +                              struct xhci_ring *ring,  struct xhci_interrupter *ir)
> > +{
> > +       union xhci_trb *current_trb;
> > +       u64 erdp_reg;
> > +       dma_addr_t deq;
> > +
> > +       /* disable irq, ack pending interrupt and ack all pending events */
> > +       xhci_disable_interrupter(ir);
> > +
> > +       /* last acked event trb is in erdp reg  */
> > +       erdp_reg = xhci_read_64(xhci, &ir->ir_set->erst_dequeue);
> > +       deq = (dma_addr_t)(erdp_reg & ERST_PTR_MASK);
> > +       if (!deq) {
> > +               xhci_err(xhci, "event ring handling not required\n");
> > +               return;
> > +       }
> > +
> > +       current_trb = ir->event_ring->dequeue;
> > +       /* read cycle state of the last acked trb to find out CCS */
> > +       ring->cycle_state = le32_to_cpu(current_trb->event_cmd.flags) & TRB_CYCLE;
> > +
> > +       xhci_handle_events(xhci, ir, true);
> > +}
> > +
> >  /*
> >   * xHCI spec says we can get an interrupt, and if the HC has an error condition,
> >   * we might get bad data out of the event ring.  Section 4.10.2.7 has a list of
> > @@ -3196,7 +3229,7 @@ irqreturn_t xhci_irq(struct usb_hcd *hcd)
> >         writel(status, &xhci->op_regs->status);
> >
> >         /* This is the handler of the primary interrupter */
> > -       xhci_handle_events(xhci, xhci->interrupters[0]);
> > +       xhci_handle_events(xhci, xhci->interrupters[0], false);
> >  out:
> >         spin_unlock(&xhci->lock);
> >
> > diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> > index 83a4adf57bae..61950a350432 100644
> > --- a/drivers/usb/host/xhci.c
> > +++ b/drivers/usb/host/xhci.c
> > @@ -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 39db228f0b84..3fa8669e3b2d 100644
> > --- a/drivers/usb/host/xhci.h
> > +++ b/drivers/usb/host/xhci.h
> > @@ -1856,6 +1856,9 @@ xhci_create_secondary_interrupter(struct usb_hcd *hcd, unsigned int segs,
> >                                   u32 imod_interval);
> >  void xhci_remove_secondary_interrupter(struct usb_hcd
> >                                        *hcd, struct xhci_interrupter *ir);
> > +void xhci_skip_sec_intr_events(struct xhci_hcd *xhci,
> > +                              struct xhci_ring *ring,
> > +                              struct xhci_interrupter *ir);
> >
> >  /* xHCI host controller glue */
> >  typedef void (*xhci_get_quirks_t)(struct device *, struct xhci_hcd *);
> > @@ -1895,6 +1898,7 @@ 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_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);
> > @@ -1939,6 +1943,9 @@ unsigned int count_trbs(u64 addr, u64 len);
> >  int xhci_stop_endpoint_sync(struct xhci_hcd *xhci, struct xhci_virt_ep *ep,
> >                             int suspend, gfp_t gfp_flags);
> >  void xhci_process_cancelled_tds(struct xhci_virt_ep *ep);
> > +void xhci_update_erst_dequeue(struct xhci_hcd *xhci,
> > +                             struct xhci_interrupter *ir,
> > +                             bool clear_ehb);
> >
> >  /* xHCI roothub code */
> >  void xhci_set_link_state(struct xhci_hcd *xhci, struct xhci_port *port,
> >
> 
> 

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