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authorOliver Neukum <oliver@neukum.org>2009-11-27 15:17:59 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2009-11-30 16:43:16 -0800
commitee4ecb8ac63a5792bec448037d4b82ec4144f94b (patch)
treeb272d4c5bcfe8ef8e7c94b6182fa2b3ed024b745 /drivers/usb/host/ehci-sched.c
parent8d6499e5bde91ad05dea4f666bdfe79e65e7cf96 (diff)
downloadlinux-stericsson-ee4ecb8ac63a5792bec448037d4b82ec4144f94b.tar.gz
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.c12
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...
*/