This patch divides ehci-hcd's interrupt handler into a top half and a
bottom half, using a tasklet to execute the latter.
The conversion is very straightforward. The only subtle point is that
we have to ignore interrupts that arrive while the tasklet is running
(i.e., from another device on a shared IRQ line).
Not-yet-signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/host/ehci-hcd.c | 56 ++++++++++++++++++++++++++++++++++++--------
drivers/usb/host/ehci.h | 4 +++
2 files changed, 51 insertions(+), 9 deletions(-)
Index: usb-3.11/drivers/usb/host/ehci.h
===================================================================
--- usb-3.11.orig/drivers/usb/host/ehci.h
+++ usb-3.11/drivers/usb/host/ehci.h
@@ -98,6 +98,10 @@ enum ehci_hrtimer_event {
#define EHCI_HRTIMER_NO_EVENT 99
struct ehci_hcd { /* one per controller */
+ /* tasklet and IRQ support */
+ struct tasklet_struct tasklet;
+ bool irqs_are_masked;
+
/* timing support */
enum ehci_hrtimer_event next_hrtimer_event;
unsigned enabled_hrtimer_events;
Index: usb-3.11/drivers/usb/host/ehci-hcd.c
===================================================================
--- usb-3.11.orig/drivers/usb/host/ehci-hcd.c
+++ usb-3.11/drivers/usb/host/ehci-hcd.c
@@ -140,6 +140,8 @@ static inline void ehci_set_intr_enable(
ehci_writel(ehci, mask, &ehci->regs->intr_enable);
}
+static void ehci_tasklet_routine(unsigned long _ehci);
+
#include "ehci-dbg.c"
/*-------------------------------------------------------------------------*/
@@ -218,6 +220,7 @@ static int ehci_halt (struct ehci_hcd *e
spin_unlock_irq(&ehci->lock);
synchronize_irq(ehci_to_hcd(ehci)->irq);
+ tasklet_kill(&ehci->tasklet);
return ehci_handshake(ehci, &ehci->regs->status,
STS_HALT, STS_HALT, 16 * 125);
@@ -468,6 +471,8 @@ static int ehci_init(struct usb_hcd *hcd
struct ehci_qh_hw *hw;
spin_lock_init(&ehci->lock);
+ tasklet_init(&ehci->tasklet, ehci_tasklet_routine,
+ (unsigned long) ehci);
/*
* keep io watchdog by default, those good HCDs could turn off it later
@@ -691,13 +696,40 @@ EXPORT_SYMBOL_GPL(ehci_setup);
/*-------------------------------------------------------------------------*/
-static irqreturn_t ehci_irq (struct usb_hcd *hcd)
+static irqreturn_t ehci_irq(struct usb_hcd *hcd)
{
struct ehci_hcd *ehci = hcd_to_ehci (hcd);
+ u32 status, masked_status;
+
+ if (ehci->irqs_are_masked)
+ return IRQ_NONE;
+
+ /*
+ * We don't use STS_FLR, but some controllers don't like it to
+ * remain on, so mask it out along with the other status bits.
+ */
+ status = ehci_readl(ehci, &ehci->regs->status);
+ masked_status = status & (INTR_MASK | STS_FLR);
+
+ /* Shared IRQ? */
+ if (!masked_status || unlikely(ehci->rh_state == EHCI_RH_HALTED))
+ return IRQ_NONE;
+
+ /* Mask IRQs and let the tasklet do the work */
+ ehci_writel(ehci, 0, &ehci->regs->intr_enable);
+ ehci->irqs_are_masked = true;
+ tasklet_hi_schedule(&ehci->tasklet);
+ return IRQ_HANDLED;
+}
+
+static void ehci_tasklet_routine(unsigned long _ehci)
+{
+ struct ehci_hcd *ehci = (struct ehci_hcd *) _ehci;
+ struct usb_hcd *hcd = ehci_to_hcd(ehci);
u32 status, masked_status, pcd_status = 0, cmd;
int bh;
- spin_lock (&ehci->lock);
+ spin_lock_irq(&ehci->lock);
status = ehci_readl(ehci, &ehci->regs->status);
@@ -713,11 +745,9 @@ static irqreturn_t ehci_irq (struct usb_
*/
masked_status = status & (INTR_MASK | STS_FLR);
- /* Shared IRQ? */
- if (!masked_status || unlikely(ehci->rh_state == EHCI_RH_HALTED)) {
- spin_unlock(&ehci->lock);
- return IRQ_NONE;
- }
+ /* IRQ already handled? */
+ if (!masked_status || unlikely(ehci->rh_state == EHCI_RH_HALTED))
+ goto done;
/* clear (just) interrupts */
ehci_writel(ehci, masked_status, &ehci->regs->status);
@@ -833,10 +863,16 @@ dead:
if (bh)
ehci_work (ehci);
- spin_unlock (&ehci->lock);
+
+ done:
+ /* Unmask IRQs again */
+ ehci->irqs_are_masked = false;
+ smp_wmb(); /* Make sure ehci_irq() sees that assignment */
+ ehci_writel(ehci, ehci->intr_mask, &ehci->regs->intr_enable);
+
+ spin_unlock_irq(&ehci->lock);
if (pcd_status)
usb_hcd_poll_rh_status(hcd);
- return IRQ_HANDLED;
}
/*-------------------------------------------------------------------------*/
@@ -1093,6 +1129,8 @@ int ehci_suspend(struct usb_hcd *hcd, bo
clear_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
spin_unlock_irq(&ehci->lock);
+ synchronize_irq(ehci_to_hcd(ehci)->irq);
+ tasklet_kill(&ehci->tasklet);
return 0;
}
EXPORT_SYMBOL_GPL(ehci_suspend);
--
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