[PATCH 5.19 125/155] usb: cdns3: fix incorrect handling TRB_SMM flag for ISOC transfer

[Greg Kroah-Hartman]

From: Pawel Laszczak <pawell@xxxxxxxxxxx>

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@xxxxxxxxxxxxxxx>
Acked-by: Peter Chen <peter.chen@xxxxxxxxxx>
Signed-off-by: Pawel Laszczak <pawell@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220825062207.5824-1-pawell@xxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/usb/cdns3/cdns3-gadget.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/usb/cdns3/cdns3-gadget.c
+++ b/drivers/usb/cdns3/cdns3-gadget.c
@@ -1530,7 +1530,8 @@ static void cdns3_transfer_completed(str
 						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);