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ehci: Don't process too much frames in 1 timer tick (v2)

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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>
This commit is contained in:
Hans de Goede 2012-09-10 12:44:11 +02:00 committed by Gerd Hoffmann
parent ffa1f2e088
commit 8f74ed1e43
1 changed files with 14 additions and 0 deletions
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14
hw/usb/hcd-ehci.c
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@ -139,6 +139,7 @@
#define NB_PORTS 6 // Number of downstream ports #define NB_PORTS 6 // Number of downstream ports
#define BUFF_SIZE 5*4096 // Max bytes to transfer per transaction #define BUFF_SIZE 5*4096 // Max bytes to transfer per transaction
#define MAX_QH 100 // Max allowable queue heads in a chain #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 /* Internal periodic / asynchronous schedule state machine states
*/ */
@ -2448,6 +2449,19 @@ static void ehci_frame_timer(void *opaque)
} }
for (i = 0; i < frames; i++) { 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_update_frindex(ehci, 1);
ehci_advance_periodic_state(ehci); ehci_advance_periodic_state(ehci);
ehci->last_run_ns += FRAME_TIMER_NS; ehci->last_run_ns += FRAME_TIMER_NS;