From: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx> [ Upstream commit 1bf661daf6b084bc4d753f55b54f35dc98709685 ] In USB2 Spec: "11.18.5 TT Response Generation In general, there will be two (or more) complete-split transactions scheduled for a periodic endpoint. However, for interrupt endpoints, the maximum size of the full-/low-speed transaction guarantees that it can never require more than two complete-split transactions. Two complete-split transactions are only required when the transaction spans a microframe boundary." Due to the maxp is 64, and less then 188 (at most in one microframe), seems never span boundary, so use only one CS for FS/LS interrupt transfer, this will save some bandwidth. Signed-off-by: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx> Link: https://lore.kernel.org/r/5b9ff09f53d23cf9e5c5437db4ffc18b798bf60c.1615170625.git.chunfeng.yun@xxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Stable-dep-of: 548011957d1d ("usb: xhci-mtk: relax TT periodic bandwidth allocation") Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/usb/host/xhci-mtk-sch.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/drivers/usb/host/xhci-mtk-sch.c b/drivers/usb/host/xhci-mtk-sch.c index 450fa22b7dc7..59ba25ca018d 100644 --- a/drivers/usb/host/xhci-mtk-sch.c +++ b/drivers/usb/host/xhci-mtk-sch.c @@ -408,13 +408,11 @@ static int check_sch_tt(struct usb_device *udev, { struct mu3h_sch_tt *tt = sch_ep->sch_tt; u32 extra_cs_count; - u32 fs_budget_start; u32 start_ss, last_ss; u32 start_cs, last_cs; int i; start_ss = offset % 8; - fs_budget_start = (start_ss + 1) % 8; if (sch_ep->ep_type == ISOC_OUT_EP) { last_ss = start_ss + sch_ep->cs_count - 1; @@ -450,16 +448,14 @@ static int check_sch_tt(struct usb_device *udev, if (sch_ep->ep_type == ISOC_IN_EP) extra_cs_count = (last_cs == 7) ? 1 : 2; else /* ep_type : INTR IN / INTR OUT */ - extra_cs_count = (fs_budget_start == 6) ? 1 : 2; + extra_cs_count = 1; cs_count += extra_cs_count; if (cs_count > 7) cs_count = 7; /* HW limit */ - for (i = 0; i < cs_count + 2; i++) { - if (test_bit(offset + i, tt->ss_bit_map)) - return -ERANGE; - } + if (test_bit(offset, tt->ss_bit_map)) + return -ERANGE; sch_ep->cs_count = cs_count; /* one for ss, the other for idle */ -- 2.35.1
