usb: dwc3: gadget: Remove END_TRANSFER delay

We had a 100us delay to synchronize the END_TRANSFER command completion
before giving back requests to the function drivers. Now, the controller
driver can handle cancelled TRBs with the requests' cancelled_list and
it can also wait until the END_TRANSFER completion before starting new
transfers. Synchronization can simply base on the controller's command
completion interrupt. The 100us delay is no longer needed. Remove this
arbitrary delay.

Signed-off-by: Thinh Nguyen <thinhn@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 696fbeb8d03a9cea377311e07c0404ffd31d4bf8..1b8014ab0b25098a3d976c98cdf036646aac885f 100644 (file)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2693,7 +2693,6 @@ static void dwc3_reset_gadget(struct dwc3 *dwc)
 static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
        bool interrupt)
 {
-       struct dwc3 *dwc = dep->dwc;
        struct dwc3_gadget_ep_cmd_params params;
        u32 cmd;
        int ret;
@@ -2709,16 +2708,13 @@ static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
         * much trouble synchronizing between us and gadget driver.
         *
         * We have discussed this with the IP Provider and it was
-        * suggested to giveback all requests here, but give HW some
-        * extra time to synchronize with the interconnect. We're using
-        * an arbitrary 100us delay for that.
+        * suggested to giveback all requests here.
         *
         * Note also that a similar handling was tested by Synopsys
         * (thanks a lot Paul) and nothing bad has come out of it.
-        * In short, what we're doing is:
-        *
-        * - Issue EndTransfer WITH CMDIOC bit set
-        * - Wait 100us
+        * In short, what we're doing is issuing EndTransfer with
+        * CMDIOC bit set and delay kicking transfer until the
+        * EndTransfer command had completed.
         *
         * As of IP version 3.10a of the DWC_usb3 IP, the controller
         * supports a mode to work around the above limitation. The
@@ -2727,8 +2723,7 @@ static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
         * by writing GUCTL2[14]. This polling is already done in the
         * dwc3_send_gadget_ep_cmd() function so if the mode is
         * enabled, the EndTransfer command will have completed upon
-        * returning from this function and we don't need to delay for
-        * 100us.
+        * returning from this function.
         *
         * This mode is NOT available on the DWC_usb31 IP.
         */
@@ -2746,9 +2741,6 @@ static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
                dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
        else
                dep->flags |= DWC3_EP_END_TRANSFER_PENDING;
-
-       if (dwc3_is_usb31(dwc) || dwc->revision < DWC3_REVISION_310A)
-               udelay(100);
 }
 
 static void dwc3_clear_stall_all_ep(struct dwc3 *dwc)