[PATCH next 1/2] 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 <redacted>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
---
 drivers/usb/host/xhci-mtk-sch.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/host/xhci-mtk-sch.c b/drivers/usb/host/xhci-mtk-sch.c
index a59d1f6d4744..7ac76ae28998 100644
--- 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 */

-- 
2.18.0
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The oops happens when unbind driver through sysfs as following,
because xhci_mtk_drop_ep() try to drop the endpoint of root hub
which is not added by xhci_add_endpoint() and the virtual device
is not allocated, in fact also needn't drop it, so should skip it.

Call trace:
 xhci_mtk_drop_ep+0x1b8/0x298
 usb_hcd_alloc_bandwidth+0x1d8/0x380
 usb_disable_device_endpoints+0x8c/0xe0
 usb_disable_device+0x128/0x168
 usb_disconnect+0xbc/0x2c8
 usb_remove_hcd+0xd8/0x210
 xhci_mtk_remove+0x98/0x108
 platform_remove+0x28/0x60
 device_release_driver_internal+0x110/0x1e8
 device_driver_detach+0x18/0x28
 unbind_store+0xd4/0x108
 drv_attr_store+0x24/0x38

Fixes: 14295a150050 ("usb: xhci-mtk: support to build xhci-mtk-hcd.ko")
Reported-by: Eddie Hung <redacted>
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
---
 drivers/usb/host/xhci-mtk-sch.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-mtk-sch.c b/drivers/usb/host/xhci-mtk-sch.c
index 7ac76ae28998..8b90da5a6ed1 100644
--- a/drivers/usb/host/xhci-mtk-sch.c
+++ b/drivers/usb/host/xhci-mtk-sch.c

@@ -872,6 +872,8 @@ int xhci_mtk_drop_ep(struct usb_hcd *hcd, struct usb_device *udev,
 	if (ret)
 		return ret;
 
-	drop_ep_quirk(hcd, udev, ep);
+	if (ep->hcpriv)
+		drop_ep_quirk(hcd, udev, ep);
+
 	return 0;
 }

-- 
2.18.0
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