Messages in this thread | | | Date | Tue, 27 Dec 2022 13:07:45 -0800 | Subject | Re: [RFC PATCH 06/14] usb: core: hcd: Introduce USB HCD APIs for interrupter management | From | Wesley Cheng <> |
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Hi Alan,
On 12/24/2022 7:29 AM, Alan Stern wrote: > On Fri, Dec 23, 2022 at 03:31:52PM -0800, Wesley Cheng wrote: >> For USB HCDs that can support multiple USB interrupters, expose functions >> that class drivers can utilize for setting up secondary interrupters. >> Class drivers can pass this information to its respective clients, i.e. >> a dedicated DSP. >> >> Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com> >> --- >> drivers/usb/core/hcd.c | 86 +++++++++++++++++++++++++++++++++++++++++ >> include/linux/usb.h | 7 ++++ >> include/linux/usb/hcd.h | 16 +++++++- >> 3 files changed, 108 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c >> index 8300baedafd2..90ead90faf1d 100644 >> --- a/drivers/usb/core/hcd.c >> +++ b/drivers/usb/core/hcd.c > >> +/** >> + * usb_hcd_stop_endpoint - Halt USB EP transfers >> + * @udev: usb device >> + * @ep: usb ep to stop >> + * >> + * Stop pending transfers on a specific USB endpoint. >> + **/ >> +int usb_hcd_stop_endpoint(struct usb_device *udev, >> + struct usb_host_endpoint *ep) >> +{ >> + struct usb_hcd *hcd = bus_to_hcd(udev->bus); >> + int ret = 0; >> + >> + if (hcd->driver->stop_endpoint) >> + ret = hcd->driver->stop_endpoint(hcd, udev, ep); >> + >> + return ret; >> +} >> +EXPORT_SYMBOL_GPL(usb_hcd_stop_endpoint); > > You know, there already is a function that does this. It's named > usb_hcd_flush_endpoint(). No need to add another function that does the > same thing. >
Thanks for the suggestion and review.
Hmmm...maybe I should change the name of the API then to avoid the confusion. Yes, usb_hcd_flush_endpoint() does ensure that URBs submitted to the EP are stopped. However, with this offloading concept, we aren't actually submitting URBs from the main processor, so the ep->urb_list will be empty.
This means the usb_hcd_flush_endpoint() API won't actually do anything. What we need is to ensure that we send a XHCI stop ep command to the controller.
Thanks Wesley Cheng
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