diff options
Diffstat (limited to 'hw/usb/hcd-ehci.c')
-rw-r--r-- | hw/usb/hcd-ehci.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c index 54273d777b..017a01de8e 100644 --- a/hw/usb/hcd-ehci.c +++ b/hw/usb/hcd-ehci.c @@ -139,6 +139,7 @@ #define NB_PORTS 6 // Number of downstream ports #define BUFF_SIZE 5*4096 // Max bytes to transfer per transaction #define MAX_QH 100 // Max allowable queue heads in a chain +#define MIN_FR_PER_TICK 3 // Min frames to process when catching up /* Internal periodic / asynchronous schedule state machine states */ @@ -2448,6 +2449,19 @@ static void ehci_frame_timer(void *opaque) } for (i = 0; i < frames; i++) { + /* + * If we're running behind schedule, we should not catch up + * too fast, as that will make some guests unhappy: + * 1) We must process a minimum of MIN_FR_PER_TICK frames, + * otherwise we will never catch up + * 2) Process frames until the guest has requested an irq (IOC) + */ + if (i >= MIN_FR_PER_TICK) { + ehci_commit_irq(ehci); + if ((ehci->usbsts & USBINTR_MASK) & ehci->usbintr) { + break; + } + } ehci_update_frindex(ehci, 1); ehci_advance_periodic_state(ehci); ehci->last_run_ns += FRAME_TIMER_NS; |