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The usb_ep_clear_halt() API can be called from the function driver, and translates to dwc3_gadget_ep_set_halt(). This routine is shared with when the host issues a clear feature ENDPOINT_HALT, and is differentiated by the protocol argument. If the following sequence occurs, there can be a situation where the delayed_status flag is improperly cleared for the wrong SETUP transaction: 1. Vendor specific control transfer returns USB_GADGET_DELAYED_STATUS. 2. DWC3 gadget sets dwc->delayed_status to '1'. 3. Another function driver issues a usb_ep_clear_halt() call. 4. DWC3 gadget issues dwc3_stop_active_transfer() and sets DWC3_EP_PENDING_CLEAR_STALL. 5. EP command complete interrupt triggers for the end transfer, and dwc3_ep0_send_delayed_status() is allowed to run, as delayed_status is '1' due to step#1. 6. STATUS phase is sent, and delayed_status is cleared. 7. Vendor specific control transfer is finished being handled, and issues usb_composite_setup_continue(). This results in queuing of a data phase. Cache the protocol flag so that DWC3 gadget is aware of when the clear halt is due to a SETUP request from the host versus when it is sourced from a function driver. This allows for the EP command complete interrupt to know if it needs to issue a delayed status phase. Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com> Link: https://lore.kernel.org/r/20220414073902.21960-1-quic_wcheng@quicinc.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.