usb: dwc3: gadget: Handle stream transfers

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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>

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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

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8

drivers/usb/dwc3/core.h

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2

drivers/usb/dwc3/debug.h

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97

drivers/usb/dwc3/gadget.c

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