diff options
Diffstat (limited to 'drivers/usb/dwc2/hcd_queue.c')
| -rw-r--r-- | drivers/usb/dwc2/hcd_queue.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/usb/dwc2/hcd_queue.c b/drivers/usb/dwc2/hcd_queue.c index 9b3c435339ee..76f3c6596bef 100644 --- a/drivers/usb/dwc2/hcd_queue.c +++ b/drivers/usb/dwc2/hcd_queue.c @@ -985,6 +985,14 @@ static int dwc2_next_periodic_start(struct dwc2_hsotg *hsotg, * and next_active_frame are always 1 frame before we want things * to be active and we assume we can still get scheduled in the * current frame number. + * - It's possible for start_active_frame (now incremented) to be + * next_active_frame if we got an EO MISS (even_odd miss) which + * basically means that we detected there wasn't enough time for + * the last packet and dwc2_hc_set_even_odd_frame() rescheduled us + * at the last second. We want to make sure we don't schedule + * another transfer for the same frame. My test webcam doesn't seem + * terribly upset by missing a transfer but really doesn't like when + * we do two transfers in the same frame. * - Some misses are expected. Specifically, in order to work * perfectly dwc2 really needs quite spectacular interrupt latency * requirements. It needs to be able to handle its interrupts @@ -995,7 +1003,8 @@ static int dwc2_next_periodic_start(struct dwc2_hsotg *hsotg, * guarantee that a system will have interrupt latency < 125 us, so * we have to be robust to some misses. */ - if (dwc2_frame_num_gt(prev_frame_number, qh->start_active_frame)) { + if (qh->start_active_frame == qh->next_active_frame || + dwc2_frame_num_gt(prev_frame_number, qh->start_active_frame)) { u16 ideal_start = qh->start_active_frame; /* Adjust interval as per gcd with plan length. */ |