Gadget driver may take an unbounded amount of time to queue requests
after XferNotReady. This is important for isochronous endpoints which
need to be started for a specific (micro-)frame.
If we fail to start a transfer for isochronous endpoint, let's try
queueing to a future interval and see if that helps. We will stop trying
if we fail a start transfer for 5 intervals in the future.
Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
---
drivers/usb/dwc3/core.h | 1 +
drivers/usb/dwc3/gadget.c | 17 ++++++++++++++---
2 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index ea59f9b4908a..85599ad6648f 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -38,6 +38,7 @@
#define DWC3_EP0_SETUP_SIZE 512
#define DWC3_ENDPOINTS_NUM 32
#define DWC3_XHCI_RESOURCES_NUM 2
+#define DWC3_ISOC_MAX_RETRIES 5
#define DWC3_SCRATCHBUF_SIZE 4096 /* each buffer is assumed to be 4KiB */
#define DWC3_EVENT_BUFFERS_SIZE 4096
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index d8c7ad0c22e8..1590516735cb 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -27,7 +27,7 @@
#include "gadget.h"
#include "io.h"
-#define DWC3_ALIGN_FRAME(d) (((d)->frame_number + (d)->interval) \
+#define DWC3_ALIGN_FRAME(d, n) (((d)->frame_number + ((d)->interval * (n))) \
& ~((d)->interval - 1))
/**
@@ -1268,13 +1268,24 @@ static int __dwc3_gadget_get_frame(struct dwc3 *dwc)
static int __dwc3_gadget_start_isoc(struct dwc3_ep *dep)
{
+ int retries;
+ int ret;
+ int i;
+
if (list_empty(&dep->pending_list)) {
dep->flags |= DWC3_EP_PENDING_REQUEST;
return -EAGAIN;
}
- dep->frame_number = DWC3_ALIGN_FRAME(dep);
- return __dwc3_gadget_kick_transfer(dep);
+ for (i = 0; i < DWC3_ISOC_MAX_RETRIES; i++) {
+ dep->frame_number = DWC3_ALIGN_FRAME(dep, i);
+
+ ret = __dwc3_gadget_kick_transfer(dep);
+ if (ret != -EAGAIN)
+ break;
+ }
+
+ return ret;
}
static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)
--
2.19.1
