target/linux/brcm2708/patches-3.10/0060-dwc_otg-fix-NAK-holdoff-and-allow-on-split-transacti.patch

   1 From 3cb2c23c6dba5ae74976e85329b880876fadd787 Mon Sep 17 00:00:00 2001
   2 From: P33M <P33M@github.com>
   3 Date: Mon, 22 Apr 2013 00:08:36 +0100
   4 Subject: [PATCH 060/196] dwc_otg: fix NAK holdoff and allow on split
   5  transactions only
   6
   7 This corrects a bug where if a single active non-periodic endpoint
   8 had at least one transaction in its qh, on frnum == MAX_FRNUM the qh
   9 would get skipped and never get queued again. This would result in
  10 a silent device until error detection (automatic or otherwise) would
  11 either reset the device or flush and requeue the URBs.
  12
  13 Additionally the NAK holdoff was enabled for all transactions - this
  14 would potentially stall a HS endpoint for 1ms if a previous error state
  15 enabled this interrupt and the next response was a NAK. Fix so that
  16 only split transactions get held off.
  17 ---
  18  drivers/usb/host/dwc_otg/dwc_otg_hcd.c | 28 ++++++++++++++++++----------
  19  1 file changed, 18 insertions(+), 10 deletions(-)
  20
  21 diff --git a/drivers/usb/host/dwc_otg/dwc_otg_hcd.c b/drivers/usb/host/dwc_otg/dwc_otg_hcd.c
  22 index 91eefec..eaa8f38 100644
  23 --- a/drivers/usb/host/dwc_otg/dwc_otg_hcd.c
  24 +++ b/drivers/usb/host/dwc_otg/dwc_otg_hcd.c
  25 @@ -46,7 +46,7 @@
  26  #include "dwc_otg_hcd.h"
  27  #include "dwc_otg_regs.h"
  28
  29 -extern bool microframe_schedule;
  30 +extern bool microframe_schedule, nak_holdoff_enable;
  31
  32  //#define DEBUG_HOST_CHANNELS
  33  #ifdef DEBUG_HOST_CHANNELS
  34 @@ -1349,18 +1349,26 @@ dwc_otg_transaction_type_e dwc_otg_hcd_select_transactions(dwc_otg_hcd_t * hcd)
  35
  36                 /*
  37                  * Check to see if this is a NAK'd retransmit, in which case ignore for retransmission
  38 -                * we hold off on bulk retransmissions to reduce NAK interrupt overhead for
  39 +                * we hold off on bulk retransmissions to reduce NAK interrupt overhead for full-speed
  40                  * cheeky devices that just hold off using NAKs
  41                  */
  42 -               if (dwc_full_frame_num(qh->nak_frame) == dwc_full_frame_num(dwc_otg_hcd_get_frame_number(hcd))) {
  43 -                       // Make fiq interrupt run on next frame (i.e. 8 uframes)
  44 -                       g_next_sched_frame = ((qh->nak_frame + 8) & ~7) & DWC_HFNUM_MAX_FRNUM;
  45 -                       qh_ptr = DWC_LIST_NEXT(qh_ptr);
  46 -                       continue;
  47 +               if (nak_holdoff_enable && qh->do_split) {
  48 +                       if (qh->nak_frame != 0xffff &&
  49 +                               dwc_full_frame_num(qh->nak_frame) ==
  50 +                               dwc_full_frame_num(dwc_otg_hcd_get_frame_number(hcd))) {
  51 +                               /*
  52 +                                * Revisit: Need to avoid trampling on periodic scheduling.
  53 +                                * Currently we are safe because g_np_count != g_np_sent whenever we hit this,
  54 +                                * but if this behaviour is changed then periodic endpoints will get a slower
  55 +                                * polling rate.
  56 +                                */
  57 +                               g_next_sched_frame = ((qh->nak_frame + 8) & ~7) & DWC_HFNUM_MAX_FRNUM;
  58 +                               qh_ptr = DWC_LIST_NEXT(qh_ptr);
  59 +                               continue;
  60 +                       } else {
  61 +                               qh->nak_frame = 0xffff;
  62 +                       }
  63                 }
  64 -               else
  65 -                       qh->nak_frame = 0xffff;
  66 -
  67                 if (microframe_schedule) {
  68                                 DWC_SPINLOCK_IRQSAVE(channel_lock, &flags);
  69                                 if (hcd->available_host_channels < 1) {
  70 --
  71 1.9.1
  72