61 lines
2.4 KiB
Diff
61 lines
2.4 KiB
Diff
From a5022829821b27e00790f8fe2fd9cd8090a47e36 Mon Sep 17 00:00:00 2001
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From: Hans de Goede <hdegoede@redhat.com>
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Date: Mon, 10 Sep 2012 12:44:11 +0200
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Subject: [PATCH] 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
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time minus 80 frames. If we make a large jump in where we are in the
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schedule, ie 40 frames, then the scheduler all of a sudden will only have
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40 frames left to work in, causing it to fail packet submissions
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with error -27 (-EFBIG).
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Changes in v2:
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-Don't hardcode a maximum number of frames to process in one tick, instead:
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-Process a minimum number of frames to ensure we do eventually catch up
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-Stop (after the minimum number) when the guest has requested an irq
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Signed-off-by: Hans de Goede <hdegoede@redhat.com>
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Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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(cherry picked from commit 8f74ed1e43263293301031a10e440549bab19a6e)
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Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
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---
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hw/usb/hcd-ehci.c | 14 ++++++++++++++
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1 file changed, 14 insertions(+)
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diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
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index 54273d7..017a01d 100644
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--- a/hw/usb/hcd-ehci.c
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+++ b/hw/usb/hcd-ehci.c
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@@ -139,6 +139,7 @@
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#define NB_PORTS 6 // Number of downstream ports
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#define BUFF_SIZE 5*4096 // Max bytes to transfer per transaction
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#define MAX_QH 100 // Max allowable queue heads in a chain
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+#define MIN_FR_PER_TICK 3 // Min frames to process when catching up
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/* Internal periodic / asynchronous schedule state machine states
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*/
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@@ -2448,6 +2449,19 @@ static void ehci_frame_timer(void *opaque)
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}
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for (i = 0; i < frames; i++) {
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+ /*
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+ * If we're running behind schedule, we should not catch up
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+ * too fast, as that will make some guests unhappy:
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+ * 1) We must process a minimum of MIN_FR_PER_TICK frames,
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+ * otherwise we will never catch up
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+ * 2) Process frames until the guest has requested an irq (IOC)
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+ */
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+ if (i >= MIN_FR_PER_TICK) {
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+ ehci_commit_irq(ehci);
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+ if ((ehci->usbsts & USBINTR_MASK) & ehci->usbintr) {
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+ break;
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+ }
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+ }
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ehci_update_frindex(ehci, 1);
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ehci_advance_periodic_state(ehci);
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ehci->last_run_ns += FRAME_TIMER_NS;
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--
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1.7.12.1
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