Previously, there was a 100uS delay inserted after issuing an end transfer
command for specific controller revisions. This was due to the fact that
there was a GUCTL2 bit field which enabled synchronous completion of the
end transfer command once the CMDACT bit was cleared in the DEPCMD
register. Since this bit does not exist for all controller revisions and
the current implementation heavily relies on utizling the EndTransfer
command completion interrupt, add the delay back in for uses where the
interrupt on completion bit is not set, and increase the duration to 1ms
for the controller to complete the command.
An issue was seen where the USB request buffer was unmapped while the DWC3
controller was still accessing the TRB. However, it was confirmed that the
end transfer command was successfully submitted. (no end transfer timeout)
In situations, such as dwc3_gadget_soft_disconnect() and
__dwc3_gadget_ep_disable(), the dwc3_remove_request() is utilized, which
will issue the end transfer command, and follow up with
dwc3_gadget_giveback(). At least for the USB ep disable path, it is
required for any pending and started requests to be completed and returned
to the function driver in the same context of the disable call. Without
the GUCTL2 bit, it is not ensured that the end transfer is completed before
the buffers are unmapped.
Fixes: cf2f8b63f7 ("usb: dwc3: gadget: Remove END_TRANSFER delay")
Cc: stable <stable@kernel.org>
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/20230306200557.29387-1-quic_wcheng@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
d8a2bb4eb7