Overview of stream transfer requirement:
* A transfer will have a set of TRBs of the same stream ID.
* A transfer is started with a stream ID in START_TRANSFER command.
* A new stream will only start when the previous completes.
Overview of stream events:
* A "prime" from host indicates that its endpoints are active
(buffers prepared and ready to receive/transmit data). The controller
automatically initiates stream if it sees this.
* A "NoStream" rejection event indicates that the host isn't ready.
Host will put the endpoint back to idle state. Device may need to
reinitiate the stream to start transfer again.
* A Stream Found event means host accepted device initiated stream.
Nothing needs to be done from driver.
To initiate a stream, the driver will issue START_TRANSFER command with
a stream ID. To reinitiate the stream, the driver must issue
END_TRANSFER and restart the transfer with START_TRANSFER command with
the same stream ID.
This implementation handles device-initated streams (e.g. UASP driver).
It also handles some hosts' quirky behavior where they only prime each
endpoint once.
Signed-off-by: Thinh Nguyen <thinhn@xxxxxxxxxxxx>
---
drivers/usb/dwc3/core.h | 8 ++++
drivers/usb/dwc3/debug.h | 2 +
drivers/usb/dwc3/gadget.c | 97 +++++++++++++++++++++++++++++++++++++++++++++--
3 files changed, 104 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index b11183a715a7..4def088329c7 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -495,6 +495,7 @@
#define DWC3_DGCMD_SELECTED_FIFO_FLUSH 0x09
#define DWC3_DGCMD_ALL_FIFO_FLUSH 0x0a
#define DWC3_DGCMD_SET_ENDPOINT_NRDY 0x0c
+#define DWC3_DGCMD_SET_ENDPOINT_PRIME 0x0d
#define DWC3_DGCMD_RUN_SOC_BUS_LOOPBACK 0x10
#define DWC3_DGCMD_STATUS(n) (((n) >> 12) & 0x0F)
@@ -702,6 +703,9 @@ struct dwc3_ep {
#define DWC3_EP_PENDING_REQUEST BIT(5)
#define DWC3_EP_DELAY_START BIT(6)
#define DWC3_EP_WAIT_TRANSFER_COMPLETE BIT(7)
+#define DWC3_EP_IGNORE_NEXT_NOSTREAM BIT(8)
+#define DWC3_EP_FORCE_RESTART_STREAM BIT(9)
+#define DWC3_EP_FIRST_STREAM_PRIMED BIT(10)
/* This last one is specific to EP0 */
#define DWC3_EP0_DIR_IN BIT(31)
@@ -1301,6 +1305,10 @@ struct dwc3_event_depevt {
#define DEPEVT_STREAMEVT_FOUND 1
#define DEPEVT_STREAMEVT_NOTFOUND 2
+/* Stream event parameter */
+#define DEPEVT_STREAM_PRIME 0xfffe
+#define DEPEVT_STREAM_NOSTREAM 0x0
+
/* Control-only Status */
#define DEPEVT_STATUS_CONTROL_DATA 1
#define DEPEVT_STATUS_CONTROL_STATUS 2
diff --git a/drivers/usb/dwc3/debug.h b/drivers/usb/dwc3/debug.h
index 0f95656c9622..d8f600e0e88f 100644
--- a/drivers/usb/dwc3/debug.h
+++ b/drivers/usb/dwc3/debug.h
@@ -68,6 +68,8 @@ dwc3_gadget_generic_cmd_string(u8 cmd)
return "All FIFO Flush";
case DWC3_DGCMD_SET_ENDPOINT_NRDY:
return "Set Endpoint NRDY";
+ case DWC3_DGCMD_SET_ENDPOINT_PRIME:
+ return "Set Endpoint Prime";
case DWC3_DGCMD_RUN_SOC_BUS_LOOPBACK:
return "Run SoC Bus Loopback Test";
default:
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 07824b670440..0380f76151a1 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -610,6 +610,9 @@ static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action)
return dwc3_send_gadget_ep_cmd(dep, DWC3_DEPCMD_SETEPCONFIG, ¶ms);
}
+static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
+ bool interrupt);
+
/**
* __dwc3_gadget_ep_enable - initializes a hw endpoint
* @dep: endpoint to be initialized
@@ -670,7 +673,7 @@ static int __dwc3_gadget_ep_enable(struct dwc3_ep *dep, unsigned int action)
* Issue StartTransfer here with no-op TRB so we can always rely on No
* Response Update Transfer command.
*/
- if ((usb_endpoint_xfer_bulk(desc) && !dep->stream_capable) ||
+ if (usb_endpoint_xfer_bulk(desc) ||
usb_endpoint_xfer_int(desc)) {
struct dwc3_gadget_ep_cmd_params params;
struct dwc3_trb *trb;
@@ -689,6 +692,29 @@ static int __dwc3_gadget_ep_enable(struct dwc3_ep *dep, unsigned int action)
ret = dwc3_send_gadget_ep_cmd(dep, cmd, ¶ms);
if (ret < 0)
return ret;
+
+ if (dep->stream_capable) {
+ /*
+ * For streams, at start, there maybe a race where the
+ * host primes the endpoint before the function driver
+ * queues a request to initiate a stream. In that case,
+ * the controller will not see the prime to generate the
+ * ERDY and start stream. To workaround this, issue a
+ * no-op TRB as normal, but end it immediately. As a
+ * result, when the function driver queues the request,
+ * the next START_TRANSFER command will cause the
+ * controller to generate an ERDY to initiate the
+ * stream.
+ */
+ dwc3_stop_active_transfer(dep, true, true);
+
+ /*
+ * All stream eps will reinitiate stream on NoStream
+ * rejection until we can determine that the host can
+ * prime after the first transfer.
+ */
+ dep->flags |= DWC3_EP_FORCE_RESTART_STREAM;
+ }
}
out:
@@ -697,8 +723,6 @@ static int __dwc3_gadget_ep_enable(struct dwc3_ep *dep, unsigned int action)
return 0;
}
-static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
- bool interrupt);
static void dwc3_remove_requests(struct dwc3 *dwc, struct dwc3_ep *dep)
{
struct dwc3_request *req;
@@ -2772,6 +2796,63 @@ static void dwc3_gadget_endpoint_transfer_not_ready(struct dwc3_ep *dep,
(void) __dwc3_gadget_start_isoc(dep);
}
+static void dwc3_gadget_endpoint_stream_event(struct dwc3_ep *dep,
+ const struct dwc3_event_depevt *event)
+{
+ struct dwc3 *dwc = dep->dwc;
+
+ if (event->status == DEPEVT_STREAMEVT_FOUND) {
+ dep->flags |= DWC3_EP_FIRST_STREAM_PRIMED;
+ goto out;
+ }
+
+ /* Note: NoStream rejection event param value is 0 and not 0xFFFF */
+ switch (event->parameters) {
+ case DEPEVT_STREAM_PRIME:
+ /*
+ * If the host can properly transition the endpoint state from
+ * idle to prime after a NoStream rejection, there's no need to
+ * force restarting the endpoint to reinitiate the stream. To
+ * simplify the check, assume the host follows the USB spec if
+ * it primed the endpoint more than once.
+ */
+ if (dep->flags & DWC3_EP_FORCE_RESTART_STREAM) {
+ if (dep->flags & DWC3_EP_FIRST_STREAM_PRIMED)
+ dep->flags &= ~DWC3_EP_FORCE_RESTART_STREAM;
+ else
+ dep->flags |= DWC3_EP_FIRST_STREAM_PRIMED;
+ }
+
+ break;
+ case DEPEVT_STREAM_NOSTREAM:
+ if ((dep->flags & DWC3_EP_IGNORE_NEXT_NOSTREAM) ||
+ !(dep->flags & DWC3_EP_FORCE_RESTART_STREAM) ||
+ !(dep->flags & DWC3_EP_WAIT_TRANSFER_COMPLETE))
+ break;
+
+ /*
+ * If the host rejects a stream due to no active stream, by the
+ * USB and xHCI spec, the endpoint will be put back to idle
+ * state. When the host is ready (buffer added/updated), it will
+ * prime the endpoint to inform the usb device controller. This
+ * triggers the device controller to issue ERDY to restart the
+ * stream. However, some hosts don't follow this and keep the
+ * endpoint in the idle state. No prime will come despite host
+ * streams are updated, and the device controller will not be
+ * triggered to generate ERDY to move the next stream data. To
+ * workaround this and maintain compatibility with various
+ * hosts, force to reinitate the stream until the host is ready
+ * instead of waiting for the host to prime the endpoint.
+ */
+ dep->flags |= DWC3_EP_DELAY_START;
+ dwc3_stop_active_transfer(dep, true, true);
+ return;
+ }
+
+out:
+ dep->flags &= ~DWC3_EP_IGNORE_NEXT_NOSTREAM;
+}
+
static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
const struct dwc3_event_depevt *event)
{
@@ -2820,6 +2901,8 @@ static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
dwc3_gadget_endpoint_transfer_complete(dep, event);
break;
case DWC3_DEPEVT_STREAMEVT:
+ dwc3_gadget_endpoint_stream_event(dep, event);
+ break;
case DWC3_DEPEVT_RXTXFIFOEVT:
break;
}
@@ -2911,6 +2994,14 @@ static void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
WARN_ON_ONCE(ret);
dep->resource_index = 0;
+ /*
+ * The END_TRANSFER command will cause the controller to generate a
+ * NoStream Event, and it's not due to the host DP NoStream rejection.
+ * Ignore the next NoStream event.
+ */
+ if (dep->stream_capable)
+ dep->flags |= DWC3_EP_IGNORE_NEXT_NOSTREAM;
+
if (!interrupt)
dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
else
--
2.11.0
