From d2901e4798cb106d5b265aa4e3ae05c06bf2bd1c Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Thu, 6 Sep 2012 17:10:48 +0200 Subject: [PATCH 360/366] ehci: Don't process too much frames in 1 timer tick 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). Note at first I had MAX_FR_PER_TICK set to 8, which works well with newer Linux guest kernels, but not with older ones (such as the RHEL-6 kernel). Signed-off-by: Hans de Goede --- hw/usb/hcd-ehci.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c index 30d2b56..5398544 100644 --- a/hw/usb/hcd-ehci.c +++ b/hw/usb/hcd-ehci.c @@ -140,6 +140,7 @@ #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 MAX_FR_PER_TICK 4 /* Max frames to process in one timer tick */ /* Internal periodic / asynchronous schedule state machine states */ @@ -2460,6 +2461,14 @@ static void ehci_frame_timer(void *opaque) DPRINTF("WARNING - EHCI skipped %d frames\n", skipped_frames); } + /* + * Processing too much frames at once causes the Linux EHCI isoc + * scheduling code to fail packet re-submissions with -EFBIG. + */ + if (frames > MAX_FR_PER_TICK) { + frames = MAX_FR_PER_TICK; + } + for (i = 0; i < frames; i++) { ehci_update_frindex(ehci, 1); ehci_advance_periodic_state(ehci); -- 1.7.12