Hello,
RL (NAK count reload) field in QH should be zero when using periodic
(interrupt) transfer.
Currently it is always set 8, but this causes high-speed interrupt transfer
malfunction in my machines, Hudson-D2 chipset(amd64) and Allwinner A10(armv7).
This causes USB2.0 hub cannot detect device attach/detach.
Here is a remedy, Linux sets the value 4 when asynchronous transfer so
I copied it.
Index: ehci.c
===================================================================
RCS file: /cvs/src/sys/dev/usb/ehci.c,v
retrieving revision 1.200
diff -u -p -r1.200 ehci.c
--- ehci.c 15 May 2017 10:52:08 -0000 1.200
+++ ehci.c 6 Jan 2019 06:08:37 -0000
@@ -1406,7 +1406,12 @@ ehci_open(struct usbd_pipe *pipe)
panic("ehci_open: bad device speed %d", dev->speed);
}
- naks = 8; /* XXX */
+ /*
+ * NAK reload count:
+ * must be zero with using periodic transfer.
+ * Linux 4.20's driver (ehci-q.c) sets 4, we use same value.
+ */
+ naks = ((xfertype == UE_CONTROL) || (xfertype == UE_BULK)) ? 4 : 0;
/* Allocate sqh for everything, save isoc xfers */
if (xfertype != UE_ISOCHRONOUS) {
--
SASANO Takayoshi (JG1UAA) <[email protected]>
