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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2007-12-06 13:28:25 -0800
committerGreg Kroah-Hartman <gregkh@suse.de>2007-12-17 10:47:15 -0800
commit565227c08226e458da191518251dbff6831624c2 (patch)
tree95571e1e6aa150aa4f7792118532f5ad89edd03e /drivers/usb
parent08cbc706acd2dd601b0663e28fa97ffb0564e105 (diff)
usb: Remove broken optimisation in OHCI IRQ handler
The OHCI IRQ handler has an optimisation that avoids reading some chip registers when the controller reports that the interrupt was triggered *only* because completed requests were written into the controller's "done list" and handed to the host. This mechanism can't be used on some controllers. Among others, it fails for the SA1111 and the AMCC 440EP PowerPC processor. This patch removes the optimisation and makes the code clearer. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/host/ohci-hcd.c23
1 files changed, 13 insertions, 10 deletions
diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c
index 704f33fdd2f..ecfe800fd72 100644
--- a/drivers/usb/host/ohci-hcd.c
+++ b/drivers/usb/host/ohci-hcd.c
@@ -732,24 +732,27 @@ static irqreturn_t ohci_irq (struct usb_hcd *hcd)
struct ohci_regs __iomem *regs = ohci->regs;
int ints;
- /* we can eliminate a (slow) ohci_readl()
- * if _only_ WDH caused this irq
+ /* Read interrupt status (and flush pending writes). We ignore the
+ * optimization of checking the LSB of hcca->done_head; it doesn't
+ * work on all systems (edge triggering for OHCI can be a factor).
*/
- if ((ohci->hcca->done_head != 0)
- && ! (hc32_to_cpup (ohci, &ohci->hcca->done_head)
- & 0x01)) {
- ints = OHCI_INTR_WDH;
+ ints = ohci_readl(ohci, &regs->intrstatus);
- /* cardbus/... hardware gone before remove() */
- } else if ((ints = ohci_readl (ohci, &regs->intrstatus)) == ~(u32)0) {
+ /* Check for an all 1's result which is a typical consequence
+ * of dead, unclocked, or unplugged (CardBus...) devices
+ */
+ if (ints == ~(u32)0) {
disable (ohci);
ohci_dbg (ohci, "device removed!\n");
return IRQ_HANDLED;
+ }
+
+ /* We only care about interrupts that are enabled */
+ ints &= ohci_readl(ohci, &regs->intrenable);
/* interrupt for some other device? */
- } else if ((ints &= ohci_readl (ohci, &regs->intrenable)) == 0) {
+ if (ints == 0)
return IRQ_NOTMINE;
- }
if (ints & OHCI_INTR_UE) {
// e.g. due to PCI Master/Target Abort