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From: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
To: Peter Chen <peter.chen@nxp.com>, linux-usb@vger.kernel.org
Cc: linux-imx@nxp.com, stable@vger.kernel.org, Jun Li <jun.li@nxp.com>
Subject: Re: [PATCH 1/1] usb: chipidea: udc: workaround for endpoint conflict issue
Date: Mon, 27 May 2019 12:02:18 +0300	[thread overview]
Message-ID: <64ff033b-7f7e-ad91-ac06-73ebd8565286@cogentembedded.com> (raw)
In-Reply-To: <20190527074222.42970-1-peter.chen@nxp.com>

On 27.05.2019 10:42, 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: <stable@vger.kernel.org> #v3.14+
> Cc: Jun Li <jun.li@nxp.com>
> Signed-off-by: Peter Chen <peter.chen@nxp.com>
> ---
>   drivers/usb/chipidea/udc.c | 24 ++++++++++++++++++++++++
>   1 file changed, 24 insertions(+)
> 
> diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
> index 829e947cabf5..411d387a45c9 100644
> --- a/drivers/usb/chipidea/udc.c
> +++ b/drivers/usb/chipidea/udc.c
> @@ -1622,6 +1622,29 @@ 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

    Um, please break the line before the function's type is fully described.

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

    Please add 1 more tab here, so that this line doesn't blend with the 
following statement.

> +		list_for_each_entry_reverse(ep, &ci->gadget.ep_list, ep_list) {
> +			if (ep->caps.dir_in && !ep->claimed)
> +				return ep;
> +		}
> +	}
> +
> +	return NULL;
> +}
> +
>   /**
>    * Device operations part of the API to the USB controller hardware,
>    * which don't involve endpoints (or i/o)
[...]

MBR, Sergei

  reply	other threads:[~2019-05-27  9:02 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-27  7:42 [PATCH 1/1] usb: chipidea: udc: workaround for endpoint conflict issue Peter Chen
2019-05-27  9:02 ` Sergei Shtylyov [this message]
2019-05-27  9:44   ` Peter Chen
2019-05-27 11:49     ` Sergei Shtylyov
2019-05-30  6:45 Peter Chen
2019-05-30  8:22 ` Sergei Shtylyov
2019-05-30  8:48   ` Peter Chen
2019-06-17  1:49 [PATCH 0/1] usb: chipidea: fixes for v5.2 Peter Chen
2019-06-17  1:49 ` [PATCH 1/1] usb: chipidea: udc: workaround for endpoint conflict issue Peter Chen

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