Re: [PATCH v2 1/1] usb: chipidea: udc: workaround for endpoint conflict issue

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, May 30, 2019 at 04:50:39PM +0800, Peter Chen wrote:
> An endpoint conflict occurs when the USB is working in device mode
> during an isochronous communication. When the endpointA IN direction
> is an isochronous IN endpoint, and the host sends an IN token to
> endpointA on another device, then the OUT transaction may be missed
> regardless the OUT endpoint number. Generally, this occurs when the
> device is connected to the host through a hub and other devices are
> connected to the same hub.
> 
> The affected OUT endpoint can be either control, bulk, isochronous, or
> an interrupt endpoint. After the OUT endpoint is primed, if an IN token
> to the same endpoint number on another device is received, then the OUT
> endpoint may be unprimed (cannot be detected by software), which causes
> this endpoint to no longer respond to the host OUT token, and thus, no
> corresponding interrupt occurs.
> 
> There is no good workaround for this issue, the only thing the software
> could do is numbering isochronous IN from the highest endpoint since we
> have observed most of device number endpoint from the lowest.
> 
> Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
> Cc: Jun Li <jun.li@nxp.com>
> Signed-off-by: Peter Chen <peter.chen@nxp.com>
> ---
> Changes for v2:
> - Improve the code sytle
> 
>  drivers/usb/chipidea/udc.c | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
> index 829e947cabf5..21c1344bfc42 100644
> --- a/drivers/usb/chipidea/udc.c
> +++ b/drivers/usb/chipidea/udc.c
> @@ -1622,6 +1622,28 @@ static int ci_udc_pullup(struct usb_gadget *_gadget, int is_on)
>  static int ci_udc_start(struct usb_gadget *gadget,
>  			 struct usb_gadget_driver *driver);
>  static int ci_udc_stop(struct usb_gadget *gadget);
> +
> +
> +/* Match ISOC IN from the highest endpoint */
> +static struct usb_ep *ci_udc_match_ep(struct usb_gadget *gadget,
> +			      struct usb_endpoint_descriptor *desc,
> +			      struct usb_ss_ep_comp_descriptor *comp_desc)
> +{
> +	struct ci_hdrc *ci = container_of(gadget, struct ci_hdrc, gadget);
> +	struct usb_ep *ep;
> +	u8 type = desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
> +
> +	if ((type == USB_ENDPOINT_XFER_ISOC) &&

usb_endpoint_xfer_isoc()?

> +			(desc->bEndpointAddress & USB_DIR_IN)) {

usb_endpoint_dir_in()?

thanks,

greg k-h