50 lines
1.8 KiB
Diff
50 lines
1.8 KiB
Diff
From d2901e4798cb106d5b265aa4e3ae05c06bf2bd1c Mon Sep 17 00:00:00 2001
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From: Hans de Goede <hdegoede@redhat.com>
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Date: Thu, 6 Sep 2012 17:10:48 +0200
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Subject: [PATCH 360/366] ehci: Don't process too much frames in 1 timer tick
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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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Note at first I had MAX_FR_PER_TICK set to 8, which works well with newer
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Linux guest kernels, but not with older ones (such as the RHEL-6 kernel).
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Signed-off-by: Hans de Goede <hdegoede@redhat.com>
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---
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hw/usb/hcd-ehci.c | 9 +++++++++
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1 file changed, 9 insertions(+)
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diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
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index 30d2b56..5398544 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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@@ -140,6 +140,7 @@
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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 MAX_FR_PER_TICK 4 /* Max frames to process in one timer tick */
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/* Internal periodic / asynchronous schedule state machine states
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*/
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@@ -2460,6 +2461,14 @@ static void ehci_frame_timer(void *opaque)
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DPRINTF("WARNING - EHCI skipped %d frames\n", skipped_frames);
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}
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+ /*
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+ * Processing too much frames at once causes the Linux EHCI isoc
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+ * scheduling code to fail packet re-submissions with -EFBIG.
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+ */
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+ if (frames > MAX_FR_PER_TICK) {
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+ frames = MAX_FR_PER_TICK;
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+ }
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+
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for (i = 0; i < frames; i++) {
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ehci_update_frindex(ehci, 1);
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ehci_advance_periodic_state(ehci);
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--
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1.7.12
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