• Pratyush Anand's avatar
    usb: dwc3: gadget: fix missed isoc · 7efea86c
    Pratyush Anand authored
    There are two reasons to generate missed isoc.
    
    1. when the host does not poll for all the data.
    2. because of application-side delays that prevent all the data from
    being transferred in programmed microframe.
    
    Current code was able to handle first case only.  This patch handles
    scenario 2 as well.Scenario 2 sometime may occur with complex gadget
    application, however it can be easily reproduced for testing purpose as
    follows:
    
    a. use isoc binterval as 1 in f_sourcesink.
    b. use pattern=0
    c. introduce a delay of 150us deliberately in source_sink_complete, so
    that after few frames it lands into scenario 2.
    d. now run testusb 16 (isoc in  test). You will notice that if this
    patch is not applied then isoc transfer is not able to recover after
    first missed.
    
    Current patch's approach is as under:
    
    If missed isoc occurs and there is no request queued then issue END
    TRANSFER, so that core generates next xfernotready and we will issue a
    fresh START TRANSFER.
    If there are still queued request then wait, do not issue either END or
    UPDATE TRANSFER, just attach next request in request_list during giveback.
    If any future queued request is successfully transferred then we will issue
    UPDATE TRANSFER for all request in the request_list.
    
    Cc: <stable@vger.kernel.org> # v3.6 v3.7 v3.8
    Signed-off-by: default avatarPratyush Anand <pratyush.anand@st.com>
    Signed-off-by: default avatarFelipe Balbi <balbi@ti.com>
    7efea86c
core.h 25.7 KB