usb: dwc3: gadget: give better command return code

if Start Transfer command fails, let's try a little
harder to figure out why the command failed and give
slightly better return codes. This will be usefulf
or isochronous endpoints, at least, which could
decide to retry a given request.

Signed-off-by: Konrad Leszczynski <konrad.leszczynski@intel.com>
Signed-off-by: Rafal Redzimski <rafal.f.redzimski@intel.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index bbbd1789596e38bbefb589b95e8ede44e4983e2c..87df6dd20d23b8e6572e0b6009b5a751b65639bb 100644 (file)
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -970,6 +970,10 @@ struct dwc3_event_depevt {
 #define DEPEVT_STATUS_CONTROL_DATA     1
 #define DEPEVT_STATUS_CONTROL_STATUS   2
 
+/* In response to Start Transfer */
+#define DEPEVT_TRANSFER_NO_RESOURCE    1
+#define DEPEVT_TRANSFER_BUS_EXPIRY     2
+
        u32     parameters:16;
 } __packed;
 

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 88fd30bf0c464ce0cf2be2abcad70037ffc6c685..43efb627d1cf179395213c841727751393648c54 100644 (file)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -287,12 +287,39 @@ int dwc3_send_gadget_ep_cmd(struct dwc3 *dwc, unsigned ep,
        do {
                reg = dwc3_readl(dwc->regs, DWC3_DEPCMD(ep));
                if (!(reg & DWC3_DEPCMD_CMDACT)) {
+                       int cmd_status = DWC3_DEPCMD_STATUS(reg);
+
                        dwc3_trace(trace_dwc3_gadget,
                                        "Command Complete --> %d",
-                                       DWC3_DEPCMD_STATUS(reg));
-                       if (DWC3_DEPCMD_STATUS(reg))
+                                       cmd_status);
+
+                       switch (cmd_status) {
+                       case 0:
+                               ret = 0;
+                               break;
+                       case DEPEVT_TRANSFER_NO_RESOURCE:
+                               dwc3_trace(trace_dwc3_gadget, "%s: no resource available");
+                               ret = -EINVAL;
                                break;
-                       ret = 0;
+                       case DEPEVT_TRANSFER_BUS_EXPIRY:
+                               /*
+                                * SW issues START TRANSFER command to
+                                * isochronous ep with future frame interval. If
+                                * future interval time has already passed when
+                                * core receives the command, it will respond
+                                * with an error status of 'Bus Expiry'.
+                                *
+                                * Instead of always returning -EINVAL, let's
+                                * give a hint to the gadget driver that this is
+                                * the case by returning -EAGAIN.
+                                */
+                               dwc3_trace(trace_dwc3_gadget, "%s: bus expiry");
+                               ret = -EAGAIN;
+                               break;
+                       default:
+                               dev_WARN(dwc->dev, "UNKNOWN cmd status\n");
+                       }
+
                        break;
                }