From ee4ecb8ac63a5792bec448037d4b82ec4144f94b Mon Sep 17 00:00:00 2001 From: Oliver Neukum Date: Fri, 27 Nov 2009 15:17:59 +0100 Subject: USB: work around for EHCI with quirky periodic schedules a quirky chipset needs periodic schedules to run for a minimum time before they can be disabled again. This enforces the requirement with a time stamp and a calculated delay Signed-off-by: Oliver Neukum Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/ehci-sched.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (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 b25cdea93a1..a5535b5e3fe 100644 --- a/drivers/usb/host/ehci-sched.c +++ b/drivers/usb/host/ehci-sched.c @@ -475,6 +475,8 @@ static int enable_periodic (struct ehci_hcd *ehci) /* make sure ehci_work scans these */ ehci->next_uframe = ehci_readl(ehci, &ehci->regs->frame_index) % (ehci->periodic_size << 3); + if (unlikely(ehci->broken_periodic)) + ehci->last_periodic_enable = ktime_get_real(); return 0; } @@ -486,6 +488,16 @@ static int disable_periodic (struct ehci_hcd *ehci) if (--ehci->periodic_sched) return 0; + if (unlikely(ehci->broken_periodic)) { + /* delay experimentally determined */ + ktime_t safe = ktime_add_us(ehci->last_periodic_enable, 1000); + ktime_t now = ktime_get_real(); + s64 delay = ktime_us_delta(safe, now); + + if (unlikely(delay > 0)) + udelay(delay); + } + /* did setting PSE not take effect yet? * takes effect only at frame boundaries... */ -- cgit v1.2.3