usb: xhci-mtk: fix wrong remainder of bandwidth budget

The remainder of the last bandwidth bugdget is wrong,
it's the value alloacted in last bugdget, not unused.

Reported-by: Yaqii Wu <Yaqii.Wu@mediatek.com>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1617179142-2681-1-git-send-email-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/xhci-mtk-sch.c b/drivers/usb/host/xhci-mtk-sch.c
index a59d1f6..7ac76ae 100644 (file)
--- a/drivers/usb/host/xhci-mtk-sch.c
+++ b/drivers/usb/host/xhci-mtk-sch.c
@@ -341,7 +341,6 @@ static void setup_sch_info(struct xhci_ep_ctx *ep_ctx,
                }
 
                if (ep_type == ISOC_IN_EP || ep_type == ISOC_OUT_EP) {
-                       u32 remainder;
 
                        if (sch_ep->esit == 1)
                                sch_ep->pkts = esit_pkts;
@@ -357,14 +356,12 @@ static void setup_sch_info(struct xhci_ep_ctx *ep_ctx,
                        sch_ep->repeat = !!(sch_ep->num_budget_microframes > 1);
                        sch_ep->bw_cost_per_microframe = maxpkt * sch_ep->pkts;
 
-                       remainder = sch_ep->bw_cost_per_microframe;
-                       remainder *= sch_ep->num_budget_microframes;
-                       remainder -= (maxpkt * esit_pkts);
                        for (i = 0; i < sch_ep->num_budget_microframes - 1; i++)
                                bwb_table[i] = sch_ep->bw_cost_per_microframe;
 
                        /* last one <= bw_cost_per_microframe */
-                       bwb_table[i] = remainder;
+                       bwb_table[i] = maxpkt * esit_pkts
+                                      - i * sch_ep->bw_cost_per_microframe;
                }
        } else if (is_fs_or_ls(sch_ep->speed)) {
                sch_ep->pkts = 1; /* at most one packet for each microframe */