Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 1833e8e0 authored by Chunfeng Yun's avatar Chunfeng Yun Committed by Greg Kroah-Hartman
Browse files

usb: xhci-mtk: add only one extra CS for FS/LS INTR 



[ 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: default avatarChunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/5b9ff09f53d23cf9e5c5437db4ffc18b798bf60c.1615170625.git.chunfeng.yun@mediatek.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 548011957d1d ("usb: xhci-mtk: relax TT periodic bandwidth allocation")
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 3826d4f0

drivers/usb/host/xhci-mtk-sch.c

+3 −7
Original line number Diff line number Diff line
@@ -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))

		if (test_bit(offset, tt->ss_bit_map))

			return -ERANGE;

		}



		sch_ep->cs_count = cs_count;

		/* one for ss, the other for idle */