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>
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index b25cdea..a5535b5 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -475,6 +475,8 @@
/* 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 @@
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...
*/