This patch implements the work around for a Mentor cotroller related
bug. This bug is observed as BULK Tx toggle error on the bus when a
BULK IO gets scheduled on an endpoint that was earlier used for
handling ISOC transaction and needed to start on 1 toggle. When such
a situation arises even if the TXCSR toggle bits are progremmed
correctly by the musb driver (for 1 toggle) when data gets transmitted
over the bus it gets transmitted with 0 toggle. This leads to toggle
error on the bus and the BULK transaction fails. In case of MSC
write the device gets reset by the Host.
This Mentor bug is observed on almost all Mentor versions (1.3, 1.5,
1.8). Confirmed on DM644x, DM355, DM365, OMAPL13x platforms.
Signed-off-by: Swaminathan S <swami.iyer@xxxxxx>
---
drivers/usb/musb/musb_host.c | 24 ++++++++++++++++++++++++
1 files changed, 24 insertions(+), 0 deletions(-)
mode change 100644 => 100755 drivers/usb/musb/musb_host.c
diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
old mode 100644
new mode 100755
index 74c4c36..c3fdd6d
--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -1771,6 +1771,9 @@ static int musb_schedule(
int best_end, epnum;
struct musb_hw_ep *hw_ep = NULL;
struct list_head *head = NULL;
+ u8 toggle;
+ u8 txtype;
+ struct urb *urb = next_urb(qh);
/* use fixed hardware for control and bulk */
if (qh->type == USB_ENDPOINT_XFER_CONTROL) {
@@ -1809,6 +1812,27 @@ static int musb_schedule(
diff -= (qh->maxpacket * qh->hb_mult);
if (diff >= 0 && best_diff > diff) {
+
+ /*
+ * Mentor controller has a bug in that if we schedule
+ * a BULK Tx transfer on an endpoint that had earlier
+ * handled ISOC then the BULK transfer has to start on
+ * a zero toggle. If the BULK transfer starts on a 1
+ * toggle then this transfer will fail as the mentor
+ * controller starts the Bulk transfer on a 0 toggle
+ * irrespective of the programming of the toggle bits
+ * in the TXCSR register. Check for this condition
+ * while allocating the EP for a Tx Bulk transfer. If
+ * so skip this EP.
+ */
+ hw_ep = musb->endpoints + epnum;
+ toggle = usb_gettoggle(urb->dev, qh->epnum, !is_in);
+ txtype = (musb_readb(hw_ep->regs, MUSB_TXTYPE)
+ >> 4) & 0x3;
+ if (!is_in && (qh->type == USB_ENDPOINT_XFER_BULK) &&
+ toggle && (txtype == USB_ENDPOINT_XFER_ISOC))
+ continue;
+
best_diff = diff;
best_end = epnum;
}
--
1.6.0.rc1.64.g61192
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