diff options
| author | Oliver Neukum <oliver@neukum.org> | 2009-11-27 17:17:59 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-12-01 03:43:16 +0300 |
| commit | ee4ecb8ac63a5792bec448037d4b82ec4144f94b (patch) | |
| tree | b272d4c5bcfe8ef8e7c94b6182fa2b3ed024b745 /drivers/usb/host/ehci-sched.c | |
| parent | 8d6499e5bde91ad05dea4f666bdfe79e65e7cf96 (diff) | |
| download | linux-ee4ecb8ac63a5792bec448037d4b82ec4144f94b.tar.xz | |
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 <oliver@neukum.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/host/ehci-sched.c')
| -rw-r--r-- | drivers/usb/host/ehci-sched.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c index b25cdea93a1f..a5535b5e3fe2 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... */ |