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SubjectRe: [PATCH v4 4/8] usb: dwc3: implement stream transfer timeout
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Hi Anurag,

On 9/8/2018 8:03 AM, Anurag Kumar Vulisha wrote:
> According to dwc3 databook when streams are used, it may be possible
> for the host and device become out of sync, where device may wait for
> host to issue prime transcation and host may wait for device to issue
> erdy. To avoid such deadlock, timeout needs to be implemented. After
> timeout occurs, device will first stop transfer and restart the transfer
> again. This patch does the same.
>
> Signed-off-by: Anurag Kumar Vulisha <anurag.kumar.vulisha@xilinx.com>
> Reviewed-by: Thinh Nguyen <thinhn@synopsys.com>
> ---
> Chnages in v4:
> 1. Added description for stream timeout timer as suggested by
> "Thinh Nguyen"
>
> Changes in v3:
> 1. Added the changes suggested by "Thinh Nguyen"
>
> Changes in v2:
> 1. Changed STREAM_TIMEOUT to STREAM_TIMEOUT_MS as suggested by
> "Andy Shevchenko"
> ---
> drivers/usb/dwc3/core.h | 7 +++++++
> drivers/usb/dwc3/gadget.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 52 insertions(+)
>
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 5bfb625..f62e8c4 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -633,6 +633,11 @@ struct dwc3_event_buffer {
>
> #define DWC3_TRB_NUM 256
>
> +/*
> + * Timeout value in msecs used by stream_timeout_timer when streams are enabled
> + */
> +#define STREAM_TIMEOUT_MS 50
> +
> /**
> * struct dwc3_ep - device side endpoint representation
> * @endpoint: usb endpoint
> @@ -656,6 +661,7 @@ struct dwc3_event_buffer {
> * @name: a human readable name e.g. ep1out-bulk
> * @direction: true for TX, false for RX
> * @stream_capable: true when streams are enabled
> + * @stream_timeout_timer: timeout timer used by bulk streams
> */
> struct dwc3_ep {
> struct usb_ep endpoint;
> @@ -705,6 +711,7 @@ struct dwc3_ep {
>
> unsigned direction:1;
> unsigned stream_capable:1;
> + struct timer_list stream_timeout_timer;
> };
>
> enum dwc3_phy {
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 13ea282..306d4c5 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -254,6 +254,7 @@ int dwc3_send_gadget_generic_command(struct dwc3 *dwc, unsigned cmd, u32 param)
> }
>
> static int __dwc3_gadget_wakeup(struct dwc3 *dwc);
> +static void stream_timeout_function(struct timer_list *arg);
>
> /**
> * dwc3_send_gadget_ep_cmd - issue an endpoint command
> @@ -574,6 +575,17 @@ static int dwc3_gadget_set_ep_config(struct dwc3_ep *dep, unsigned int action)
> | DWC3_DEPCFG_STREAM_EVENT_EN
> | DWC3_DEPCFG_XFER_COMPLETE_EN;
> dep->stream_capable = true;
> +
> + /*
> + * When BULK streams are enabled it may be possible for the host
> + * and device become out of sync, where device may wait for host
> + * to issue prime transcation and host may wait for device to
> + * issue ERDY. To avoid such deadlock, timeout needs to be
> + * implemented. After timeout occurs, device will first stop
> + * transfer and restart the transfer again.
> + */
> + timer_setup(&dep->stream_timeout_timer,
> + stream_timeout_function, 0);
> }
>
> if (!usb_endpoint_xfer_control(desc))
> @@ -730,6 +742,9 @@ static int __dwc3_gadget_ep_disable(struct dwc3_ep *dep)
>
> trace_dwc3_gadget_ep_disable(dep);
>
> + if (dep->stream_capable)
> + del_timer(&dep->stream_timeout_timer);
> +
> dwc3_remove_requests(dwc, dep);
>
> /* make sure HW endpoint isn't stalled */
> @@ -1257,6 +1272,12 @@ static int __dwc3_gadget_kick_transfer(struct dwc3_ep *dep)
> return ret;
> }
>
> + if (starting && dep->stream_capable) {
> + dep->stream_timeout_timer.expires = jiffies +
> + msecs_to_jiffies(STREAM_TIMEOUT_MS);
> + add_timer(&dep->stream_timeout_timer);
> + }
> +
> return 0;
> }
>
> @@ -2403,6 +2424,13 @@ static void dwc3_gadget_endpoint_transfer_in_progress(struct dwc3_ep *dep,
> stop = true;
> }
>
> + /*
> + * Delete the timer that was started in __dwc3_gadget_kick_transfer()
> + * for stream capable endpoints.
> + */
> + if (dep->stream_capable)
> + del_timer(&dep->stream_timeout_timer);
> +
> dwc3_gadget_ep_cleanup_completed_requests(dep, event, status);
>
> if (stop) {
> @@ -2487,6 +2515,11 @@ static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
> }
> break;
> case DWC3_DEPEVT_STREAMEVT:
> + if (event->status == DEPEVT_STREAMEVT_FOUND)
> + del_timer(&dep->stream_timeout_timer);
> + else
> + dev_dbg(dwc->dev, "unable to find suitable stream");

This debug message is already printed in the driver tracepoint. There's
no need to print it here. Also, I don't think Felipe will accept adding
new dev_dbg() after removing all of them and converting them to tracepoints.

Thinh

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