Commit 6ccb83d6 authored by Udipto Goswami's avatar Udipto Goswami Committed by Greg Kroah-Hartman
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usb: xhci: Implement xhci_handshake_check_state() helper 



In some situations where xhci removal happens parallel to xhci_handshake,
we encounter a scenario where the xhci_handshake can't succeed, and it
polls until timeout.

If xhci_handshake runs until timeout it can on some platforms result in
a long wait which might lead to a watchdog timeout.

Add a helper that checks xhci status during the handshake, and exits if
set state is entered. Use this helper in places where xhci_handshake is
called unlocked and has a long timeout. For example  xhci command timeout
and xhci reset.

[commit message and code comment rewording -Mathias]

Signed-off-by: default avatarUdipto Goswami <quic_ugoswami@quicinc.com>
Signed-off-by: default avatarMathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20231019102924.2797346-18-mathias.nyman@linux.intel.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 47f503cf

drivers/usb/host/xhci-ring.c

+3 −2
Original line number Diff line number Diff line
@@ -450,8 +450,9 @@ 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,

			CMD_RING_RUNNING, 0, 5 * 1000 * 1000);

	ret = xhci_handshake_check_state(xhci, &xhci->op_regs->cmd_ring,

			CMD_RING_RUNNING, 0, 5 * 1000 * 1000,

			XHCI_STATE_REMOVING);

	if (ret < 0) {

		xhci_err(xhci, "Abort failed to stop command ring: %d\n", ret);

		xhci_halt(xhci);

drivers/usb/host/xhci.c

+25 −1
Original line number Diff line number Diff line
@@ -81,6 +81,29 @@ int xhci_handshake(void __iomem *ptr, u32 mask, u32 done, u64 timeout_us) 
	return ret;

}



/*

 * xhci_handshake_check_state - same as xhci_handshake but takes an additional

 * exit_state parameter, and bails out with an error immediately when xhc_state

 * has exit_state flag set.

 */

int xhci_handshake_check_state(struct xhci_hcd *xhci, void __iomem *ptr,

		u32 mask, u32 done, int usec, unsigned int exit_state)

{

	u32	result;

	int	ret;



	ret = readl_poll_timeout_atomic(ptr, result,

				(result & mask) == done ||

				result == U32_MAX ||

				xhci->xhc_state & exit_state,

				1, usec);



	if (result == U32_MAX || xhci->xhc_state & exit_state)

		return -ENODEV;



	return ret;

}



/*

 * Disable interrupts and begin the xHCI halting process.

 */
@@ -201,7 +224,8 @@ 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, XHCI_STATE_REMOVING);

	if (ret)

		return ret;

drivers/usb/host/xhci.h

+2 −0
Original line number Diff line number Diff line
@@ -2084,6 +2084,8 @@ 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, unsigned int exit_state);

void xhci_quiesce(struct xhci_hcd *xhci);

int xhci_halt(struct xhci_hcd *xhci);

int xhci_start(struct xhci_hcd *xhci);