From sarah.a.sharp@linux.intel.com Tue Jun 1 13:37:36 2010 From: Sarah Sharp Date: Mon, 24 May 2010 13:25:21 -0700 Subject: USB: xhci: Wait for host to start running. To: Greg KH Cc: linux-usb@vger.kernel.org, Shinya Saito Message-ID: <20100524202521.GA5074@xanatos> Content-Disposition: inline When the run bit is set in the xHCI command register, it may take a few microseconds for the host to start running. We cannot ring any doorbells until the host is actually running, so wait until the status register says the host is running. Signed-off-by: Sarah Sharp Reported-by: Shinya Saito Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/xhci.c | 39 ++++++++++++++++++++++++++++++++------- 1 file changed, 32 insertions(+), 7 deletions(-) --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -106,6 +106,33 @@ int xhci_halt(struct xhci_hcd *xhci) } /* + * Set the run bit and wait for the host to be running. + */ +int xhci_start(struct xhci_hcd *xhci) +{ + u32 temp; + int ret; + + temp = xhci_readl(xhci, &xhci->op_regs->command); + temp |= (CMD_RUN); + xhci_dbg(xhci, "// Turn on HC, cmd = 0x%x.\n", + temp); + xhci_writel(xhci, temp, &xhci->op_regs->command); + + /* + * Wait for the HCHalted Status bit to be 0 to indicate the host is + * running. + */ + ret = handshake(xhci, &xhci->op_regs->status, + STS_HALT, 0, XHCI_MAX_HALT_USEC); + if (ret == -ETIMEDOUT) + xhci_err(xhci, "Host took too long to start, " + "waited %u microseconds.\n", + XHCI_MAX_HALT_USEC); + return ret; +} + +/* * Reset a halted HC, and set the internal HC state to HC_STATE_HALT. * * This resets pipelines, timers, counters, state machines, etc. @@ -460,13 +487,11 @@ int xhci_run(struct usb_hcd *hcd) if (NUM_TEST_NOOPS > 0) doorbell = xhci_setup_one_noop(xhci); - temp = xhci_readl(xhci, &xhci->op_regs->command); - temp |= (CMD_RUN); - xhci_dbg(xhci, "// Turn on HC, cmd = 0x%x.\n", - temp); - xhci_writel(xhci, temp, &xhci->op_regs->command); - /* Flush PCI posted writes */ - temp = xhci_readl(xhci, &xhci->op_regs->command); + if (xhci_start(xhci)) { + xhci_halt(xhci); + return -ENODEV; + } + xhci_dbg(xhci, "// @%p = 0x%x\n", &xhci->op_regs->command, temp); if (doorbell) (*doorbell)(xhci);