Hi, On Fri, May 16, 2014 at 11:50:13PM +0800, Zhuang Jin Can wrote: > > On Fri, May 16, 2014 at 05:57:57AM +0800, Zhuang Jin Can wrote: > > > In ISOC transfers, when free_slot points to the last TRB (i.e. Link > > > TRB), and all queued requests meet Missed Interval Isoc error, busy_slot > > > points to trb0. > > > busy_slot->trb0 > > > trb1 > > > ... > > > free_slot->trb31(Link TRB) > > > > > > After end transfer and receiving the XferNotReady event, trb_left is > > > caculated as 1 which is wrong, and no TRB will be primed to the > > > endpoint. > > > > > > The root cause is free_slot is not increased the same way as busy_slot. > > > When busy_slot is increased by one, it checks if points to a link TRB > > > after increasement, but free_slot checks it before increasement. > > > free_slot should behave the same as busy_slot to make the trb_left > > > caculation correct. > > > > > > Signed-off-by: Zhuang Jin Can <jin.can.zhuang@xxxxxxxxx> > > > Signed-off-by: Jiebing Li <jiebing.li@xxxxxxxxx> > > > --- > > > drivers/usb/dwc3/gadget.c | 8 ++++---- > > > 1 file changed, 4 insertions(+), 4 deletions(-) > > > > > > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c > > > index 54da8c8..2ebe82b 100644 > > > --- a/drivers/usb/dwc3/gadget.c > > > +++ b/drivers/usb/dwc3/gadget.c > > > @@ -828,10 +828,6 @@ static void dwc3_prepare_one_trb(struct dwc3_ep *dep, > > > length, last ? " last" : "", > > > chain ? " chain" : ""); > > > > > > - /* Skip the LINK-TRB on ISOC */ > > > - if (((dep->free_slot & DWC3_TRB_MASK) == DWC3_TRB_NUM - 1) && > > > - usb_endpoint_xfer_isoc(dep->endpoint.desc)) > > > - dep->free_slot++; > > > > > > trb = &dep->trb_pool[dep->free_slot & DWC3_TRB_MASK]; > > > > I have a feeling this has a negative side effect of letting us use the > > link TRB for data transfer... I mean, if we don't increment free_slot > > before accessing our trb_pool, we have no way to skip link trb on this > > access here. > After every free_slot++ Link TRB is checked and increased if appropriate, > this guarantees you next time access free_slot, it can't be a Link > TRB. right, next access will be fine, but you're forgetting about current access. > > How did you find the bug ? do you have good instructions on how to > > reproduce it ? How did you test the patch and for how long ? > The bug is reproduced on Android with f_audio_source.c enabled, which > has an isoc-in endpoint keeps sending audio data to host in an interval > of 1 ms. Normally, you need to run for 12+ hours to hit the issue. > So I think you can just run some isoc transfers for a long time to > reproduce it. To accelarte the reproducing, you can run some concurrent > data transfer as well, so the possibility to meet missed interval error > is larger. > > The patch is tested for basic functionality like enumeration, data > transfers. For this bug, it was tested for 20+ hours. thanks, g_audio loop should be fine. -- balbi
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