Thinh Nguyen [off-list ref] writes:

The driver incorrectly uses req->num_pending_sgs to track both the
number of pending and queued SG entries. It only prepares the next
request if the previous is done, and it doesn't update num_pending_sgs
until there is TRB completion interrupt. This may starve the controller
of more TRBs until the num_pending_sgs is decremented.

Fix this by decrementing the num_pending_sgs after they are queued and
properly track both num_mapped_sgs and num_queued_sgs.

Cc: <redacted>
Tested-by: Michael Grzeschik <redacted>
Reported-by: Michael Grzeschik <redacted>
Fixes: c96e6725db9d ("usb: dwc3: gadget: Correct the logic for queuing sgs")
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>

Acked-by: Felipe Balbi <balbi@kernel.org>

-- 
balbi