Availability of TRB's are calculated using dwc3_calc_trbs_left(), which determines available TRB's based on the HWO bit set in a TRB. __dwc3_prepare_one_trb() is called with a TRB which needs to be prepared for transfer. This __dwc3_prepare_one_trb() calls dwc3_calc_trbs_left() to determine total available TRBs and set IOC bit if the total available TRBs are zero. Since the present working TRB(which is passed as an argument to __dwc3_prepare_one_trb() ) doesn't have HWO bit already set, there are chances where dwc3_calc_trbs_left() wrongly calculates this present working TRB as free(since the HWO bit is not yet set). This could be a problem. This patch correct this issue by setting HWO bit before calling dwc3_calc_trbs_left() Signed-off-by: Anurag Kumar Vulisha <anurag.kumar.vulisha@xxxxxxxxxx> Reviewed-by: Thinh Nguyen <thinhn@xxxxxxxxxxxx> --- Changes in v3: 1. Corrected the logic for setting HWO bit as suggested by "Thinh Nguyen" Changes in v2: 1. Changed the commit message --- drivers/usb/dwc3/gadget.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index 032ea7d..8a1622b 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -911,8 +911,6 @@ static void __dwc3_prepare_one_trb(struct dwc3_ep *dep, struct dwc3_trb *trb, struct usb_gadget *gadget = &dwc->gadget; enum usb_device_speed speed = gadget->speed; - dwc3_ep_inc_enq(dep); - trb->size = DWC3_TRB_SIZE_LENGTH(length); trb->bpl = lower_32_bits(dma); trb->bph = upper_32_bits(dma); @@ -991,7 +989,7 @@ static void __dwc3_prepare_one_trb(struct dwc3_ep *dep, struct dwc3_trb *trb, } if ((!no_interrupt && !chain) || - (dwc3_calc_trbs_left(dep) == 0)) + (dwc3_calc_trbs_left(dep) == 1)) trb->ctrl |= DWC3_TRB_CTRL_IOC; if (chain) @@ -1002,6 +1000,8 @@ static void __dwc3_prepare_one_trb(struct dwc3_ep *dep, struct dwc3_trb *trb, trb->ctrl |= DWC3_TRB_CTRL_HWO; + dwc3_ep_inc_enq(dep); + trace_dwc3_prepare_trb(dep, trb); } -- 2.1.1
