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-rw-r--r--drivers/usb/host/ehci-sched.c11
1 files changed, 6 insertions, 5 deletions
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index ebcca970067..88419c6823a 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -707,6 +707,7 @@ iso_stream_init (
} else {
u32 addr;
int think_time;
+ int hs_transfers;
addr = dev->ttport << 24;
if (!ehci_is_TDI(ehci)
@@ -719,6 +720,7 @@ iso_stream_init (
think_time = dev->tt ? dev->tt->think_time : 0;
stream->tt_usecs = NS_TO_US (think_time + usb_calc_bus_time (
dev->speed, is_input, 1, maxp));
+ hs_transfers = max (1u, (maxp + 187) / 188);
if (is_input) {
u32 tmp;
@@ -727,12 +729,11 @@ iso_stream_init (
stream->usecs = HS_USECS_ISO (1);
stream->raw_mask = 1;
- /* pessimistic c-mask */
- tmp = usb_calc_bus_time (USB_SPEED_FULL, 1, 0, maxp)
- / (125 * 1000);
- stream->raw_mask |= 3 << (tmp + 9);
+ /* c-mask as specified in USB 2.0 11.18.4 3.c */
+ tmp = (1 << (hs_transfers + 2)) - 1;
+ stream->raw_mask |= tmp << (8 + 2);
} else
- stream->raw_mask = smask_out [maxp / 188];
+ stream->raw_mask = smask_out [hs_transfers - 1];
bandwidth = stream->usecs + stream->c_usecs;
bandwidth /= 1 << (interval + 2);