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authorStephen Warren <swarren@nvidia.com>2014-02-07 09:53:50 -0700
committerMarek Vasut <marex@denx.de>2014-03-10 18:53:36 +0100
commit2456b97f0c9411d0bc2637ba1033a910c8b4b971 (patch)
tree1c88cdc0bf55fb5c4fd9ca8d3ac6aac104167ba1 /drivers/usb/host
parent247161b8160fc699b0a517f081220bb50bc502a8 (diff)
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ush: ehci: initialize altnext pointers in QH
Section 4.10.2 "Advance Queue" of ehci-specification-for-usb.pdf specifies how an EHCI controller loads a new QTD for processing if the QH is not already marked as active. It states: ===== If the field Bytes to Transfer is not zero and the T-bit in the Alternate Next qTD Pointer is set to zero, then the host controller uses the Alternate Next qTD Pointer. Otherwise, the host controller uses the Next qTD Pointer. If Next qTD Pointer’s T-bit is set to a one, then the host controller exits this state and uses the horizontal pointer to the next schedule data structure. ===== Hence, we must ensure that the alternate next QTD pointer's T-bit (TERMINATE) is set, so the EHCI controller knows to use the next QTD pointer. Signed-off-by: Stephen Warren <swarren@nvidia.com>
Diffstat (limited to 'drivers/usb/host')
-rw-r--r--drivers/usb/host/ehci-hcd.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index 17187ca..7068b76 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -395,6 +395,7 @@ ehci_submit_async(struct usb_device *dev, unsigned long pipe, void *buffer,
QH_ENDPT2_UFCMASK(0) | QH_ENDPT2_UFSMASK(0);
qh->qh_endpt2 = cpu_to_hc32(endpt);
qh->qh_overlay.qt_next = cpu_to_hc32(QT_NEXT_TERMINATE);
+ qh->qh_overlay.qt_altnext = cpu_to_hc32(QT_NEXT_TERMINATE);
tdp = &qh->qh_overlay.qt_next;
@@ -1186,6 +1187,7 @@ create_int_queue(struct usb_device *dev, unsigned long pipe, int queuesize,
qh->qh_link = QH_LINK_TERMINATE;
qh->qh_overlay.qt_next = (uint32_t)td;
+ qh->qh_overlay.qt_altnext = QT_NEXT_TERMINATE;
qh->qh_endpt1 = (0 << 28) | /* No NAK reload (ehci 4.9) */
(usb_maxpacket(dev, pipe) << 16) | /* MPS */
(1 << 14) |