usb: cdns3: fix incorrect handling TRB_SMM flag for ISOC transfer

commit d5dcc33677d7415c5f23b3c052f9e80cbab9ea4e upstream.

The TRB_SMM flag indicates that DMA has completed the TD service with
this TRB. Usually it’s a last TRB in TD. In case of ISOC transfer for
bInterval > 1 each ISOC transfer contains more than one TD associated
with usb request (one TD per ITP). In such case the TRB_SMM flag will
be set in every TD and driver will recognize the end of transfer after
processing the first TD with TRB_SMM. In result driver stops updating
request->actual and returns incorrect actual length.
To fix this issue driver additionally must check TRB_CHAIN which is not
used for isochronous transfers.

Fixes: 249f0a25e8be ("usb: cdns3: gadget: handle sg list use case at completion correctly")
cc: <stable@vger.kernel.org>
Acked-by: Peter Chen <peter.chen@kernel.org>
Signed-off-by: Pawel Laszczak <pawell@cadence.com>
Link: https://lore.kernel.org/r/20220825062207.5824-1-pawell@cadence.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
index 621e696..1802f68 100644 (file)
--- a/drivers/usb/cdns3/cdns3-gadget.c
+++ b/drivers/usb/cdns3/cdns3-gadget.c
@@ -1530,7 +1530,8 @@ static void cdns3_transfer_completed(struct cdns3_device *priv_dev,
                                                TRB_LEN(le32_to_cpu(trb->length));
 
                                if (priv_req->num_of_trb > 1 &&
-                                       le32_to_cpu(trb->control) & TRB_SMM)
+                                       le32_to_cpu(trb->control) & TRB_SMM &&
+                                       le32_to_cpu(trb->control) & TRB_CHAIN)
                                        transfer_end = true;
 
                                cdns3_ep_inc_deq(priv_ep);