From 1e12c910eed82da6971f1c0421a069c680faba2e Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Tue, 17 May 2011 10:40:51 -0400 Subject: EHCI: don't rescan interrupt QHs needlessly This patch (as1466) speeds up processing of ehci-hcd's periodic list. The existing code will pointlessly rescan an interrupt endpoint queue each time it encounters the queue's QH in the periodic list, which can happen quite a few times if the endpoint's period is low. On some embedded systems, this useless overhead can waste so much time that the driver falls hopelessly behind and loses events. The patch introduces a "periodic_stamp" variable, which gets incremented each time scan_periodic() runs and each time the scan advances to a new frame. If the corresponding stamp in an interrupt QH is equal to the current periodic_stamp, we assume the QH has already been scanned and skip over it. Otherwise we scan the QH as usual, and if none of its URBs have completed then we store the current periodic_stamp in the QH's stamp, preventing it from being scanned again. Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/ehci-sched.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'drivers/usb/host/ehci-sched.c') diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c index 1543c83..a7408d8 100644 --- a/drivers/usb/host/ehci-sched.c +++ b/drivers/usb/host/ehci-sched.c @@ -2287,6 +2287,7 @@ scan_periodic (struct ehci_hcd *ehci) } clock &= mod - 1; clock_frame = clock >> 3; + ++ehci->periodic_stamp; for (;;) { union ehci_shadow q, *q_p; @@ -2315,10 +2316,14 @@ restart: temp.qh = qh_get (q.qh); type = Q_NEXT_TYPE(ehci, q.qh->hw->hw_next); q = q.qh->qh_next; - modified = qh_completions (ehci, temp.qh); - if (unlikely(list_empty(&temp.qh->qtd_list) || - temp.qh->needs_rescan)) - intr_deschedule (ehci, temp.qh); + if (temp.qh->stamp != ehci->periodic_stamp) { + modified = qh_completions(ehci, temp.qh); + if (!modified) + temp.qh->stamp = ehci->periodic_stamp; + if (unlikely(list_empty(&temp.qh->qtd_list) || + temp.qh->needs_rescan)) + intr_deschedule(ehci, temp.qh); + } qh_put (temp.qh); break; case Q_TYPE_FSTN: @@ -2460,6 +2465,7 @@ restart: if (ehci->clock_frame != clock_frame) { free_cached_lists(ehci); ehci->clock_frame = clock_frame; + ++ehci->periodic_stamp; } } else { now_uframe++; -- cgit v1.1 From 69fff59de4d844f8b4c2454c3c23d32b69dcbfd7 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Tue, 17 May 2011 17:27:12 -0400 Subject: USB: remove remaining usages of hcd->state from usbcore and fix regression This patch (as1467) removes the last usages of hcd->state from usbcore. We no longer check to see if an interrupt handler finds that a controller has died; instead we rely on host controller drivers to make an explicit call to usb_hc_died(). This fixes a regression introduced by commit 9b37596a2e860404503a3f2a6513db60c296bfdc (USB: move usbcore away from hcd->state). It used to be that when a controller shared an IRQ with another device and an interrupt arrived while hcd->state was set to HC_STATE_HALT, the interrupt handler would be skipped. The commit removed that test; as a result the current code doesn't skip calling the handler and ends up believing the controller has died, even though it's only temporarily stopped. The solution is to ignore HC_STATE_HALT following the handler's return. As a consequence of this change, several of the host controller drivers need to be modified. They can no longer implicitly rely on usbcore realizing that a controller has died because of hcd->state. The patch adds calls to usb_hc_died() in the appropriate places. The patch also changes a few of the interrupt handlers. They don't expect to be called when hcd->state is equal to HC_STATE_HALT, even if the controller is still alive. Early returns were added to avoid any confusion. Signed-off-by: Alan Stern Tested-by: Manuel Lauss CC: Rodolfo Giometti CC: Olav Kongas CC: Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/ehci-sched.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'drivers/usb/host/ehci-sched.c') diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c index a7408d8..6c9fbe3 100644 --- a/drivers/usb/host/ehci-sched.c +++ b/drivers/usb/host/ehci-sched.c @@ -471,8 +471,10 @@ static int enable_periodic (struct ehci_hcd *ehci) */ status = handshake_on_error_set_halt(ehci, &ehci->regs->status, STS_PSS, 0, 9 * 125); - if (status) + if (status) { + usb_hc_died(ehci_to_hcd(ehci)); return status; + } cmd = ehci_readl(ehci, &ehci->regs->command) | CMD_PSE; ehci_writel(ehci, cmd, &ehci->regs->command); @@ -510,8 +512,10 @@ static int disable_periodic (struct ehci_hcd *ehci) */ status = handshake_on_error_set_halt(ehci, &ehci->regs->status, STS_PSS, STS_PSS, 9 * 125); - if (status) + if (status) { + usb_hc_died(ehci_to_hcd(ehci)); return status; + } cmd = ehci_readl(ehci, &ehci->regs->command) & ~CMD_PSE; ehci_writel(ehci, cmd, &ehci->regs->command); -- cgit v1.1