4.20-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit b7a4fbe2300a8965ea760c7e871507b84aea17f6 ] Availability of TRB's is calculated using dwc3_calc_trbs_left(), which determines total available TRB's based on the HWO bit set in a TRB. In the present code, __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 yet have the HWO bit set before calling dwc3_calc_trbs_left(), there are chances that dwc3_calc_trbs_left() wrongly calculates this present working TRB as free(since the HWO bit is not yet set) and returns the total available TRBs as greater than zero (including the present working TRB). This could be a problem. This patch corrects the above mentioned problem in __dwc3_prepare_one_trb() by increementing the dep->trb_enqueue at the last (after preparing the TRB) instead of increementing at the start and setting the IOC bit only if the total available TRBs returned by dwc3_calc_trbs_left() is 1 . Since we are increementing the dep->trb_enqueue at the last, the present working TRB is also considered as available by dwc3_calc_trbs_left() and non zero value is returned . So, according to the modified logic, when the total available TRBs is equal to 1 that means the total available TRBs in the pool are 0. Signed-off-by: Anurag Kumar Vulisha <anurag.kumar.vulisha@xxxxxxxxxx> Reviewed-by: Thinh Nguyen <thinhn@xxxxxxxxxxxx> Tested-by: Tejas Joglekar <tejas.joglekar@xxxxxxxxxxxx> Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- 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 2a4ea9a1b1e3..88f69d823be5 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -921,8 +921,6 @@ 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); @@ -1001,7 +999,7 @@ 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) @@ -1012,6 +1010,8 @@ 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); } -- 2.19.1
