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USB: EHCI: fix up locking
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This patch (as1588) adjusts the locking in ehci-hcd's various halt,
shutdown, and suspend/resume pathways.  We want to hold the spinlock
while writing device registers and accessing shared variables, but not
while polling in a loop.

In addition, there's no need to call ehci_work() at times when no URBs
can be active, i.e., in ehci_stop() and ehci_bus_suspend().

Finally, ehci_adjust_port_wakeup_flags() is called only in situations
where interrupts are enabled; therefore it can use spin_lock_irq
rather than spin_lock_irqsave.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Alan Stern authored and Greg Kroah-Hartman committed Jul 16, 2012
1 parent f428907 commit c4f3476
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Showing 3 changed files with 64 additions and 30 deletions.
48 changes: 33 additions & 15 deletions drivers/usb/host/ehci-hcd.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -167,21 +167,24 @@ static int tdi_in_host_mode (struct ehci_hcd *ehci)
return (tmp & 3) == USBMODE_CM_HC;
}

/* force HC to halt state from unknown (EHCI spec section 2.3) */
/*
* Force HC to halt state from unknown (EHCI spec section 2.3).
* Must be called with interrupts enabled and the lock not held.
*/
static int ehci_halt (struct ehci_hcd *ehci)
{
u32 temp = ehci_readl(ehci, &ehci->regs->status);
u32 temp;

spin_lock_irq(&ehci->lock);

/* disable any irqs left enabled by previous code */
ehci_writel(ehci, 0, &ehci->regs->intr_enable);

if (ehci_is_TDI(ehci) && tdi_in_host_mode(ehci) == 0) {
if (ehci_is_TDI(ehci) && !tdi_in_host_mode(ehci)) {
spin_unlock_irq(&ehci->lock);
return 0;
}

if ((temp & STS_HALT) != 0)
return 0;

/*
* This routine gets called during probe before ehci->command
* has been initialized, so we can't rely on its value.
Expand All @@ -190,7 +193,11 @@ static int ehci_halt (struct ehci_hcd *ehci)
temp = ehci_readl(ehci, &ehci->regs->command);
temp &= ~(CMD_RUN | CMD_IAAD);
ehci_writel(ehci, temp, &ehci->regs->command);
return handshake (ehci, &ehci->regs->status,

spin_unlock_irq(&ehci->lock);
synchronize_irq(ehci_to_hcd(ehci)->irq);

return handshake(ehci, &ehci->regs->status,
STS_HALT, STS_HALT, 16 * 125);
}

Expand All @@ -210,7 +217,10 @@ static void tdi_reset (struct ehci_hcd *ehci)
ehci_writel(ehci, tmp, &ehci->regs->usbmode);
}

/* reset a non-running (STS_HALT == 1) controller */
/*
* Reset a non-running (STS_HALT == 1) controller.
* Must be called with interrupts enabled and the lock not held.
*/
static int ehci_reset (struct ehci_hcd *ehci)
{
int retval;
Expand Down Expand Up @@ -248,7 +258,10 @@ static int ehci_reset (struct ehci_hcd *ehci)
return retval;
}

/* idle the controller (from running) */
/*
* Idle the controller (turn off the schedules).
* Must be called with interrupts enabled and the lock not held.
*/
static void ehci_quiesce (struct ehci_hcd *ehci)
{
u32 temp;
Expand All @@ -261,8 +274,10 @@ static void ehci_quiesce (struct ehci_hcd *ehci)
handshake(ehci, &ehci->regs->status, STS_ASS | STS_PSS, temp, 16 * 125);

/* then disable anything that's still active */
spin_lock_irq(&ehci->lock);
ehci->command &= ~(CMD_ASE | CMD_PSE);
ehci_writel(ehci, ehci->command, &ehci->regs->command);
spin_unlock_irq(&ehci->lock);

/* hardware can take 16 microframes to turn off ... */
handshake(ehci, &ehci->regs->status, STS_ASS | STS_PSS, 0, 16 * 125);
Expand Down Expand Up @@ -301,18 +316,22 @@ static void ehci_turn_off_all_ports(struct ehci_hcd *ehci)

/*
* Halt HC, turn off all ports, and let the BIOS use the companion controllers.
* Should be called with ehci->lock held.
* Must be called with interrupts enabled and the lock not held.
*/
static void ehci_silence_controller(struct ehci_hcd *ehci)
{
ehci_halt(ehci);

spin_lock_irq(&ehci->lock);
ehci->rh_state = EHCI_RH_HALTED;
ehci_turn_off_all_ports(ehci);

/* make BIOS/etc use companion controller during reboot */
ehci_writel(ehci, 0, &ehci->regs->configured_flag);

/* unblock posted writes */
ehci_readl(ehci, &ehci->regs->configured_flag);
spin_unlock_irq(&ehci->lock);
}

/* ehci_shutdown kick in for silicon on any bus (not just pci, etc).
Expand All @@ -325,10 +344,11 @@ static void ehci_shutdown(struct usb_hcd *hcd)

spin_lock_irq(&ehci->lock);
ehci->rh_state = EHCI_RH_STOPPING;
ehci_silence_controller(ehci);
ehci->enabled_hrtimer_events = 0;
spin_unlock_irq(&ehci->lock);

ehci_silence_controller(ehci);

hrtimer_cancel(&ehci->hrtimer);
}

Expand Down Expand Up @@ -400,20 +420,18 @@ static void ehci_stop (struct usb_hcd *hcd)

spin_lock_irq(&ehci->lock);
ehci->enabled_hrtimer_events = 0;
ehci_quiesce(ehci);
spin_unlock_irq(&ehci->lock);

ehci_quiesce(ehci);
ehci_silence_controller(ehci);
ehci_reset (ehci);
spin_unlock_irq(&ehci->lock);

hrtimer_cancel(&ehci->hrtimer);
remove_sysfs_files(ehci);
remove_debug_files (ehci);

/* root hub is shut down separately (first, when possible) */
spin_lock_irq (&ehci->lock);
if (ehci->async)
ehci_work (ehci);
end_free_itds(ehci);
spin_unlock_irq (&ehci->lock);
ehci_mem_cleanup (ehci);
Expand Down
41 changes: 29 additions & 12 deletions drivers/usb/host/ehci-hub.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,7 @@ static void ehci_handover_companion_ports(struct ehci_hcd *ehci)
/* Give the connections some time to appear */
msleep(20);

spin_lock_irq(&ehci->lock);
port = HCS_N_PORTS(ehci->hcs_params);
while (port--) {
if (test_bit(port, &ehci->owned_ports)) {
Expand All @@ -70,23 +71,30 @@ static void ehci_handover_companion_ports(struct ehci_hcd *ehci)
clear_bit(port, &ehci->owned_ports);
else if (test_bit(port, &ehci->companion_ports))
ehci_writel(ehci, status & ~PORT_PE, reg);
else
else {
spin_unlock_irq(&ehci->lock);
ehci_hub_control(hcd, SetPortFeature,
USB_PORT_FEAT_RESET, port + 1,
NULL, 0);
spin_lock_irq(&ehci->lock);
}
}
}
spin_unlock_irq(&ehci->lock);

if (!ehci->owned_ports)
return;
msleep(90); /* Wait for resets to complete */

spin_lock_irq(&ehci->lock);
port = HCS_N_PORTS(ehci->hcs_params);
while (port--) {
if (test_bit(port, &ehci->owned_ports)) {
spin_unlock_irq(&ehci->lock);
ehci_hub_control(hcd, GetPortStatus,
0, port + 1,
(char *) &buf, sizeof(buf));
spin_lock_irq(&ehci->lock);

/* The companion should now own the port,
* but if something went wrong the port must not
Expand All @@ -105,6 +113,7 @@ static void ehci_handover_companion_ports(struct ehci_hcd *ehci)
}

ehci->owned_ports = 0;
spin_unlock_irq(&ehci->lock);
}

static int ehci_port_change(struct ehci_hcd *ehci)
Expand Down Expand Up @@ -133,7 +142,6 @@ static void ehci_adjust_port_wakeup_flags(struct ehci_hcd *ehci,
{
int port;
u32 temp;
unsigned long flags;

/* If remote wakeup is enabled for the root hub but disabled
* for the controller, we must adjust all the port wakeup flags
Expand All @@ -143,7 +151,7 @@ static void ehci_adjust_port_wakeup_flags(struct ehci_hcd *ehci,
if (!ehci_to_hcd(ehci)->self.root_hub->do_remote_wakeup || do_wakeup)
return;

spin_lock_irqsave(&ehci->lock, flags);
spin_lock_irq(&ehci->lock);

/* clear phy low-power mode before changing wakeup flags */
if (ehci->has_hostpc) {
Expand All @@ -154,9 +162,9 @@ static void ehci_adjust_port_wakeup_flags(struct ehci_hcd *ehci,
temp = ehci_readl(ehci, hostpc_reg);
ehci_writel(ehci, temp & ~HOSTPC_PHCD, hostpc_reg);
}
spin_unlock_irqrestore(&ehci->lock, flags);
spin_unlock_irq(&ehci->lock);
msleep(5);
spin_lock_irqsave(&ehci->lock, flags);
spin_lock_irq(&ehci->lock);
}

port = HCS_N_PORTS(ehci->hcs_params);
Expand Down Expand Up @@ -194,7 +202,7 @@ static void ehci_adjust_port_wakeup_flags(struct ehci_hcd *ehci,
if (!suspending && ehci_port_change(ehci))
usb_hcd_resume_root_hub(ehci_to_hcd(ehci));

spin_unlock_irqrestore(&ehci->lock, flags);
spin_unlock_irq(&ehci->lock);
}

static int ehci_bus_suspend (struct usb_hcd *hcd)
Expand All @@ -209,6 +217,9 @@ static int ehci_bus_suspend (struct usb_hcd *hcd)
if (time_before (jiffies, ehci->next_statechange))
msleep(5);

/* stop the schedules */
ehci_quiesce(ehci);

spin_lock_irq (&ehci->lock);

/* Once the controller is stopped, port resumes that are already
Expand All @@ -224,10 +235,6 @@ static int ehci_bus_suspend (struct usb_hcd *hcd)
}
}

/* stop schedules, clean any completed work */
ehci_quiesce(ehci);
ehci_work(ehci);

/* Unlike other USB host controller types, EHCI doesn't have
* any notion of "global" or bus-wide suspend. The driver has
* to manually suspend all the active unsuspended ports, and
Expand Down Expand Up @@ -289,13 +296,16 @@ static int ehci_bus_suspend (struct usb_hcd *hcd)
"succeeded" : "failed");
}
}
spin_unlock_irq(&ehci->lock);

/* Apparently some devices need a >= 1-uframe delay here */
if (ehci->bus_suspended)
udelay(150);

/* turn off now-idle HC */
ehci_halt (ehci);

spin_lock_irq(&ehci->lock);
ehci->rh_state = EHCI_RH_SUSPENDED;

end_unlink_async(ehci);
Expand Down Expand Up @@ -424,13 +434,14 @@ static int ehci_bus_resume (struct usb_hcd *hcd)
}

ehci->next_statechange = jiffies + msecs_to_jiffies(5);
spin_unlock_irq(&ehci->lock);

ehci_handover_companion_ports(ehci);

/* Now we can safely re-enable irqs */
ehci_writel(ehci, INTR_MASK, &ehci->regs->intr_enable);
(void) ehci_readl(ehci, &ehci->regs->intr_enable);

spin_unlock_irq (&ehci->lock);
ehci_handover_companion_ports(ehci);
return 0;
}

Expand Down Expand Up @@ -1018,7 +1029,9 @@ static int ehci_hub_control (
case USB_PORT_FEAT_TEST:
if (!selector || selector > 5)
goto error;
spin_unlock_irqrestore(&ehci->lock, flags);
ehci_quiesce(ehci);
spin_lock_irqsave(&ehci->lock, flags);

/* Put all enabled ports into suspend */
while (ports--) {
Expand All @@ -1030,7 +1043,11 @@ static int ehci_hub_control (
ehci_writel(ehci, temp | PORT_SUSPEND,
sreg);
}

spin_unlock_irqrestore(&ehci->lock, flags);
ehci_halt(ehci);
spin_lock_irqsave(&ehci->lock, flags);

temp = ehci_readl(ehci, status_reg);
temp |= selector << 16;
ehci_writel(ehci, temp, status_reg);
Expand Down
5 changes: 2 additions & 3 deletions drivers/usb/host/ehci-tegra.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -445,12 +445,11 @@ static int controller_suspend(struct device *dev)
if (time_before(jiffies, ehci->next_statechange))
msleep(10);

spin_lock_irqsave(&ehci->lock, flags);
ehci_halt(ehci);

spin_lock_irqsave(&ehci->lock, flags);
tegra->port_speed = (readl(&hw->port_status[0]) >> 26) & 0x3;
ehci_halt(ehci);
clear_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);

spin_unlock_irqrestore(&ehci->lock, flags);

tegra_ehci_power_down(hcd);
Expand Down

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