Commit 140ca4cf authored by Thinh Nguyen's avatar Thinh Nguyen Committed by Felipe Balbi
Browse files

usb: dwc3: gadget: Handle stream transfers 



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: default avatarThinh Nguyen <thinhn@synopsys.com>
Signed-off-by: default avatarFelipe Balbi <balbi@kernel.org>
parent aefe3d23

drivers/usb/dwc3/core.h

+8 −0
Original line number Diff line number Diff line
@@ -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

drivers/usb/dwc3/debug.h

+2 −0
Original line number Diff line number Diff line
@@ -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:

drivers/usb/dwc3/gadget.c

+94 −3
Original line number Diff line number Diff line
@@ -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, &params);

}



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, &params);

		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