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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: Thinh Nguyen <thinhn@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
This commit is contained in:
Thinh Nguyen 2020-05-05 19:47:09 -07:00 committed by Felipe Balbi
parent aefe3d232b
commit 140ca4cfea
3 changed files with 104 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
drivers/usb/dwc3/core.h
View File

@ -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

2
drivers/usb/dwc3/debug.h
View File

@ -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:

97
drivers/usb/dwc3/gadget.c
View File

@ -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