| Message ID | 20230915091737.31721-1-quic_ugoswami@quicinc.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [RFC] usb: XHCI: Implement xhci_handshake_check_state() API | expand |
On 15.9.2023 12.17, Udipto Goswami wrote: > In some situations where xhci removal happens parallel to > xhci_handshake, we enoughter a scenario where the > xhci_handshake will fails because the status does not change > the entire duration of polling. This causes the xhci_handshake > to timeout resulting in long wait which might lead to watchdog > timeout. > > The API handles command timeout which may happen upon XHCI > stack removal. Check for xhci state and exit the handshake if > xhci is removed. > > Signed-off-by: Udipto Goswami <quic_ugoswami@quicinc.com> > --- > drivers/usb/host/xhci-ring.c | 2 +- > drivers/usb/host/xhci.c | 27 ++++++++++++++++++++++++++- > drivers/usb/host/xhci.h | 2 ++ > 3 files changed, 29 insertions(+), 2 deletions(-) > > diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c > index 1dde53f6eb31..af9e27d3d303 100644 > --- a/drivers/usb/host/xhci-ring.c > +++ b/drivers/usb/host/xhci-ring.c > @@ -450,7 +450,7 @@ static int xhci_abort_cmd_ring(struct xhci_hcd *xhci, unsigned long flags) > * In the future we should distinguish between -ENODEV and -ETIMEDOUT > * and try to recover a -ETIMEDOUT with a host controller reset. > */ > - ret = xhci_handshake(&xhci->op_regs->cmd_ring, > + ret = xhci_handshake_check_state(xhci, &xhci->op_regs->cmd_ring, > CMD_RING_RUNNING, 0, 5 * 1000 * 1000); > if (ret < 0) { > xhci_err(xhci, "Abort failed to stop command ring: %d\n", ret); > diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c > index e1b1b64a0723..7bfcb09bcad0 100644 > --- a/drivers/usb/host/xhci.c > +++ b/drivers/usb/host/xhci.c > @@ -84,6 +84,30 @@ int xhci_handshake(void __iomem *ptr, u32 mask, u32 done, u64 timeout_us) > /* > * Disable interrupts and begin the xHCI halting process. > */ > +int xhci_handshake_check_state(struct xhci_hcd *xhci, > + void __iomem *ptr, u32 mask, u32 done, int usec) > +{ > + u32 result; > + > + do { > + result = readl_relaxed(ptr); > + if (result == ~(u32)0) > + return -ENODEV; > + > + if (xhci->xhc_state & XHCI_STATE_REMOVING) > + return -ENODEV; > + > + result &= mask; > + if (result == done) > + return 0; > + > + udelay(1); > + usec--; > + } while (usec > 0); > + > + return -ETIMEDOUT; > +} > + Could we use the same readl_poll_timeout_atomic() macro that xhci_handshake() does? Something like: int xhci_handshake_check_state(struct xhci_hcd *xhci, void __iomem *ptr, u32 mask, u32 done, int usec, unsigned int exit_state) { ... ret = readl_poll_timeout_atomic(ptr, result, (result & mask) == done || result == U32_MAX || xhci->xhc_state & exit_state, 1, timeout_us); if (result == U32_MAX || xhci->xch_state & exit_state) return -ENODEV; return ret; } -Mathias
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index 1dde53f6eb31..af9e27d3d303 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -450,7 +450,7 @@ static int xhci_abort_cmd_ring(struct xhci_hcd *xhci, unsigned long flags) * In the future we should distinguish between -ENODEV and -ETIMEDOUT * and try to recover a -ETIMEDOUT with a host controller reset. */ - ret = xhci_handshake(&xhci->op_regs->cmd_ring, + ret = xhci_handshake_check_state(xhci, &xhci->op_regs->cmd_ring, CMD_RING_RUNNING, 0, 5 * 1000 * 1000); if (ret < 0) { xhci_err(xhci, "Abort failed to stop command ring: %d\n", ret); diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index e1b1b64a0723..7bfcb09bcad0 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -84,6 +84,30 @@ int xhci_handshake(void __iomem *ptr, u32 mask, u32 done, u64 timeout_us) /* * Disable interrupts and begin the xHCI halting process. */ +int xhci_handshake_check_state(struct xhci_hcd *xhci, + void __iomem *ptr, u32 mask, u32 done, int usec) +{ + u32 result; + + do { + result = readl_relaxed(ptr); + if (result == ~(u32)0) + return -ENODEV; + + if (xhci->xhc_state & XHCI_STATE_REMOVING) + return -ENODEV; + + result &= mask; + if (result == done) + return 0; + + udelay(1); + usec--; + } while (usec > 0); + + return -ETIMEDOUT; +} + void xhci_quiesce(struct xhci_hcd *xhci) { u32 halted; @@ -201,7 +225,8 @@ int xhci_reset(struct xhci_hcd *xhci, u64 timeout_us) if (xhci->quirks & XHCI_INTEL_HOST) udelay(1000); - ret = xhci_handshake(&xhci->op_regs->command, CMD_RESET, 0, timeout_us); + ret = xhci_handshake_check_state(xhci, &xhci->op_regs->command, + CMD_RESET, 0, timeout_us); if (ret) return ret; diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h index 7e282b4522c0..504c04d19c05 100644 --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -2119,6 +2119,8 @@ void xhci_free_container_ctx(struct xhci_hcd *xhci, /* xHCI host controller glue */ typedef void (*xhci_get_quirks_t)(struct device *, struct xhci_hcd *); int xhci_handshake(void __iomem *ptr, u32 mask, u32 done, u64 timeout_us); +int xhci_handshake_check_state(struct xhci_hcd *xhci, + void __iomem *ptr, u32 mask, u32 done, int usec); void xhci_quiesce(struct xhci_hcd *xhci); int xhci_halt(struct xhci_hcd *xhci); int xhci_start(struct xhci_hcd *xhci);
In some situations where xhci removal happens parallel to xhci_handshake, we enoughter a scenario where the xhci_handshake will fails because the status does not change the entire duration of polling. This causes the xhci_handshake to timeout resulting in long wait which might lead to watchdog timeout. The API handles command timeout which may happen upon XHCI stack removal. Check for xhci state and exit the handshake if xhci is removed. Signed-off-by: Udipto Goswami <quic_ugoswami@quicinc.com> --- drivers/usb/host/xhci-ring.c | 2 +- drivers/usb/host/xhci.c | 27 ++++++++++++++++++++++++++- drivers/usb/host/xhci.h | 2 ++ 3 files changed, 29 insertions(+), 2 deletions(-)