From 5e8ec28765cd65b078c03d11a5e47e326f738def Mon Sep 17 00:00:00 2001 From: John Youn Date: Thu, 19 May 2016 17:26:17 -0700 Subject: [PATCH] UPSTREAM: usb: dwc3: gadget: Handle TRB index 0 when full or empty If the trb->enqueue == trb->dequeue, then it could be full or empty. This could also happen at TRB index 0, so modify the check to handle that condition. At index 0, the previous TRB is the one just before the link TRB. Change-Id: I17d5fd4e7592507dac08bef6c458ff14d7426461 Signed-off-by: John Youn Signed-off-by: Felipe Balbi Signed-off-by: Wu Liang feng (cherry picked from commit 361572b5f7a95b341a92d34b9bf41f71bbdae34d) --- drivers/usb/dwc3/gadget.c | 28 ++++++++++++++++++++++------ 1 file changed, 22 insertions(+), 6 deletions(-) diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index f027d4b32997..c8c07f667636 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -842,6 +842,25 @@ static void dwc3_prepare_one_trb(struct dwc3_ep *dep, trace_dwc3_prepare_trb(dep, trb); } +/** + * dwc3_ep_prev_trb() - Returns the previous TRB in the ring + * @dep: The endpoint with the TRB ring + * @index: The index of the current TRB in the ring + * + * Returns the TRB prior to the one pointed to by the index. If the + * index is 0, we will wrap backwards, skip the link TRB, and return + * the one just before that. + */ +static struct dwc3_trb *dwc3_ep_prev_trb(struct dwc3_ep *dep, u8 index) +{ + if (!index) + index = DWC3_TRB_NUM - 2; + else + index = dep->trb_enqueue - 1; + + return &dep->trb_pool[index]; +} + static u32 dwc3_calc_trbs_left(struct dwc3_ep *dep) { struct dwc3_trb *tmp; @@ -855,12 +874,9 @@ static u32 dwc3_calc_trbs_left(struct dwc3_ep *dep) * more transfers in our ring. */ if (dep->trb_enqueue == dep->trb_dequeue) { - /* If we're full, enqueue/dequeue are > 0 */ - if (dep->trb_enqueue) { - tmp = &dep->trb_pool[dep->trb_enqueue - 1]; - if (tmp->ctrl & DWC3_TRB_CTRL_HWO) - return 0; - } + tmp = dwc3_ep_prev_trb(dep, dep->trb_enqueue); + if (tmp->ctrl & DWC3_TRB_CTRL_HWO) + return 0; return DWC3_TRB_NUM - 1; } -- 2.34.1