[PATCH v8 10/25] usb: dwc3: gadget: flush and invalidate cache around transfers

[Anders Roxell <anders.roxell@linaro.org>]

Same problem as ep0, but for the normal endpoints. In u-boot the trb
pool and the request buffers are plain cached memory, so the controller
and the CPU do not see the same data. The resync dropped the cache
maintenance u-boot had here.

Without it the controller reads a stale trb and no data moves. DFU still
works because it goes over ep0, but ums does not. The device enumerates
and usb-storage binds, but no disk shows up and the host gives up after
20 seconds.

Flush the data buffer and the trb once the trb is set up. Invalidate the
trb before reading it back, and the request buffer before handing it to
the gadget driver.

Tested on BeagleBoard-X15 with ums.

Reported-by: Anshul Dalal <anshuld@ti.com>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
---
 drivers/usb/dwc3/gadget.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index b3a371df3749..fd0ae9e3e092 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -228,6 +228,10 @@ void dwc3_gadget_giveback(struct dwc3_ep *dep, struct dwc3_request *req,
 	dwc3_gadget_del_and_unmap_request(dep, req, status);
 	req->status = DWC3_REQUEST_STATUS_COMPLETED;
 
+	if (req->request.dma && req->request.length)
+		dwc3_invalidate_cache((uintptr_t)req->request.dma,
+				      req->request.length);
+
 	spin_unlock(&dwc->lock);
 	usb_gadget_giveback_request(&dep->endpoint, &req->request);
 	spin_lock(&dwc->lock);
@@ -1385,6 +1389,9 @@ static void dwc3_prepare_one_trb(struct dwc3_ep *dep,
 	wmb();
 	trb->ctrl |= DWC3_TRB_CTRL_HWO;
 
+	dwc3_flush_cache((uintptr_t)dma, trb_length);
+	dwc3_flush_cache((uintptr_t)trb, sizeof(*trb));
+
 	dwc3_ep_inc_enq(dep);
 }
 
@@ -3153,6 +3160,8 @@ static int dwc3_gadget_ep_reclaim_completed_trb(struct dwc3_ep *dep,
 {
 	unsigned int		count;
 
+	dwc3_invalidate_cache((uintptr_t)trb, sizeof(*trb));
+
 	dwc3_ep_inc_deq(dep);
 
 	req->num_trbs--;
-- 
2.53.0