diff options
author | Hans de Goede <hdegoede@redhat.com> | 2012-09-10 12:44:11 +0200 |
---|---|---|
committer | Gerd Hoffmann <kraxel@redhat.com> | 2012-09-12 08:09:49 +0200 |
commit | 8f74ed1e43263293301031a10e440549bab19a6e (patch) | |
tree | d63514e77356995891e55c9d2727bc2d25753528 /hw/usb/hcd-ehci.c | |
parent | ffa1f2e088eb7e3d57f2fc35f21e7bdb23e592c5 (diff) |
ehci: Don't process too much frames in 1 timer tick (v2)
The Linux ehci isoc scheduling code fills the entire schedule ahead of
time minus 80 frames. If we make a large jump in where we are in the
schedule, ie 40 frames, then the scheduler all of a sudden will only have
40 frames left to work in, causing it to fail packet submissions
with error -27 (-EFBIG).
Changes in v2:
-Don't hardcode a maximum number of frames to process in one tick, instead:
-Process a minimum number of frames to ensure we do eventually catch up
-Stop (after the minimum number) when the guest has requested an irq
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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; |