Wesley Cheng wrote:
> In the DWC3 databook, for a device initiated disconnect or bus reset, the
> driver is required to send dependxfer commands for any pending transfers.
> In addition, before the controller can move to the halted state, the SW
> needs to acknowledge any pending events. If the controller is not halted
> properly, there is a chance the controller will continue accessing stale or
> freed TRBs and buffers.
>
> Signed-off-by: Wesley Cheng <wcheng@xxxxxxxxxxxxxx>
>
> ---
> Changes in v2:
> - Moved cleanup code to the pullup() API to differentiate between device
> disconnect and hibernation.
> - Added cleanup code to the bus reset case as well.
> - Verified the move to pullup() did not reproduce the problen using the
> same test sequence.
>
> Verified fix by adding a check for ETIMEDOUT during the run stop call.
> Shell script writing to the configfs UDC file to trigger disconnect and
> connect. Batch script to have PC execute data transfers over adb (ie adb
> push) After a few iterations, we'd run into a scenario where the
> controller wasn't halted. With the following change, no failed halts after
> many iterations.
> ---
> drivers/usb/dwc3/ep0.c | 2 +-
> drivers/usb/dwc3/gadget.c | 52 ++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 52 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
> index 59f2e8c31bd1..456aa87e8778 100644
> --- a/drivers/usb/dwc3/ep0.c
> +++ b/drivers/usb/dwc3/ep0.c
> @@ -197,7 +197,7 @@ int dwc3_gadget_ep0_queue(struct usb_ep *ep, struct usb_request *request,
> int ret;
>
> spin_lock_irqsave(&dwc->lock, flags);
> - if (!dep->endpoint.desc) {
> + if (!dep->endpoint.desc || !dwc->pullups_connected) {
> dev_err(dwc->dev, "%s: can't queue to disabled endpoint\n",
> dep->name);
> ret = -ESHUTDOWN;
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 3ab6f118c508..df8d89d6bdc9 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -1516,7 +1516,7 @@ static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)
> {
> struct dwc3 *dwc = dep->dwc;
>
> - if (!dep->endpoint.desc) {
> + if (!dep->endpoint.desc || !dwc->pullups_connected) {
> dev_err(dwc->dev, "%s: can't queue to disabled endpoint\n",
> dep->name);
> return -ESHUTDOWN;
> @@ -1926,6 +1926,24 @@ static int dwc3_gadget_set_selfpowered(struct usb_gadget *g,
> return 0;
> }
>
> +static void dwc3_stop_active_transfers(struct dwc3 *dwc)
> +{
> + u32 epnum;
> +
> + for (epnum = 2; epnum < DWC3_ENDPOINTS_NUM; epnum++) {
> + struct dwc3_ep *dep;
> +
> + dep = dwc->eps[epnum];
> + if (!dep)
> + continue;
> +
> + if (!(dep->flags & DWC3_EP_ENABLED))
> + continue;
Don't do the enabled check here. Let the dwc3_stop_active_transfer() do
that checking.
> +
> + dwc3_remove_requests(dwc, dep);
> + }
> +}
> +
> static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on, int suspend)
> {
> u32 reg;
> @@ -1994,9 +2012,39 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
> }
> }
>
> + /*
> + * Synchronize and disable any further event handling while controller
> + * is being enabled/disabled.
> + */
> + disable_irq(dwc->irq_gadget);
I think it's better to do dwc3_gadget_disable_irq(). This only stops
handling events. Although it's unlikely, the controller may still
generate events before it's halted.
> spin_lock_irqsave(&dwc->lock, flags);
> +
> + /* Controller is not halted until pending events are acknowledged */
> + if (!is_on) {
> + u32 reg;
> +
> + __dwc3_gadget_ep_disable(dwc->eps[0]);
> + __dwc3_gadget_ep_disable(dwc->eps[1]);
You can just do __dwc3_gadget_stop(), and do that after
dwc3_stop_active_transfers().
> +
> + /*
> + * The databook explicitly mentions for a device-initiated
> + * disconnect sequence, the SW needs to ensure that it ends any
> + * active transfers.
> + */
> + dwc3_stop_active_transfers(dwc);
> +
> + reg = dwc3_readl(dwc->regs, DWC3_GEVNTCOUNT(0));
> + reg &= DWC3_GEVNTCOUNT_MASK;
Can we use another variable "count" instead of reusing reg to make it a
little clearer?
> + if (reg > 0) {
> + dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), reg);
> + dwc->ev_buf->lpos = (dwc->ev_buf->lpos + reg) %
> + dwc->ev_buf->length;
> + }
> + }
> +
> ret = dwc3_gadget_run_stop(dwc, is_on, false);
> spin_unlock_irqrestore(&dwc->lock, flags);
> + enable_irq(dwc->irq_gadget);
>
> return ret;
> }
> @@ -3100,6 +3148,8 @@ static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)
> }
>
> dwc3_reset_gadget(dwc);
> + /* Stop any active/pending transfers when receiving bus reset */
> + dwc3_stop_active_transfers(dwc);
>
> reg = dwc3_readl(dwc->regs, DWC3_DCTL);
> reg &= ~DWC3_DCTL_TSTCTRL_MASK;
Looks good to me.
Thanks,
Thinh
