[PATCH v3 0/2] Handle core soft reset failure in pullup

[PATCH v3 0/2] Handle core soft reset failure in pullup

[Krishna Kurapati]

When core soft reset timeout happens, pullup doesn't check for the
return value and proceeds setting up of event buffers and starts the
controller.

In this scneario, it is observed sometimes that the GEVTADDR LO/HI
registers read zero while we are setting the run stop bit and we end
up accessing address 0x00 leading to a crash. This series tries to
address this issue by handling the timeout and return back appropriate
error code to configfs for it to retry enumeration if it chooses to.

Link to v1: https://lore.kernel.org/all/20230322092740.28491-1-quic_kriskura@quicinc.com/
Link to v2: https://lore.kernel.org/all/20230328160756.30520-1-quic_kriskura@quicinc.com/

changes in v3:
Rebased on top of latest usb-next to resolve merge issues
Fixed comments from v2 related to code styling

changes in v2:
Fixed comments addressing incomplete error handling in udc core

Krishna Kurapati (2):
  usb: dwc3: gadget: Bail out in pullup if soft reset timeout happens
  usb: gadget: udc: Handle gadget_connect failure during bind operation

 drivers/usb/dwc3/gadget.c     |  5 ++++-
 drivers/usb/gadget/udc/core.c | 21 +++++++++++++++++----
 2 files changed, 21 insertions(+), 5 deletions(-)

-- 
2.40.0

[PATCH v3 1/2] usb: dwc3: gadget: Bail out in pullup if soft reset timeout happens

[Krishna Kurapati]

If the core soft reset timeout happens, avoid setting up event
buffers and starting gadget as the writes to these registers
may not reflect when in reset and setting the run stop bit
can lead the controller to access wrong event buffer address
resulting in a crash.

Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
---
changes in v3: Rebase on top of usb-next

 drivers/usb/dwc3/gadget.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index c0ca4d12f95d..9ab5161881bd 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2746,13 +2746,16 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 		 * device-initiated disconnect requires a core soft reset
 		 * (DCTL.CSftRst) before enabling the run/stop bit.
 		 */
-		dwc3_core_soft_reset(dwc);
+		ret = dwc3_core_soft_reset(dwc);
+		if (ret)
+			goto done;
 
 		dwc3_event_buffers_setup(dwc);
 		__dwc3_gadget_start(dwc);
 		ret = dwc3_gadget_run_stop(dwc, true);
 	}
 
+done:
 	pm_runtime_put(dwc->dev);
 
 	return ret;
-- 
2.40.0

[PATCH v3 2/2] usb: gadget: udc: Handle gadget_connect failure during bind operation

[Krishna Kurapati]

In the event, gadget_connect call (which invokes pullup) fails,
propagate the error to udc bind operation which inturn sends the
error to configfs. The userspace can then retry enumeartion if
it chooses to.

Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
---
changes in v3: Rebase on top of usb-next

 drivers/usb/gadget/udc/core.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
index 4641153e9706..69041cca5d24 100644
--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -1122,12 +1122,16 @@ EXPORT_SYMBOL_GPL(usb_gadget_set_state);
 /* ------------------------------------------------------------------------- */
 
 /* Acquire connect_lock before calling this function. */
-static void usb_udc_connect_control_locked(struct usb_udc *udc) __must_hold(&udc->connect_lock)
+static int usb_udc_connect_control_locked(struct usb_udc *udc) __must_hold(&udc->connect_lock)
 {
+	int ret;
+
 	if (udc->vbus && udc->started)
-		usb_gadget_connect_locked(udc->gadget);
+		ret = usb_gadget_connect_locked(udc->gadget);
 	else
-		usb_gadget_disconnect_locked(udc->gadget);
+		ret = usb_gadget_disconnect_locked(udc->gadget);
+
+	return ret;
 }
 
 /**
@@ -1583,12 +1587,21 @@ static int gadget_bind_driver(struct device *dev)
 		goto err_start;
 	}
 	usb_gadget_enable_async_callbacks(udc);
-	usb_udc_connect_control_locked(udc);
+	ret = usb_udc_connect_control_locked(udc);
+	if (ret)
+		goto err_connect_control;
+
 	mutex_unlock(&udc->connect_lock);
 
 	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
 	return 0;
 
+ err_connect_control:
+	usb_gadget_disable_async_callbacks(udc);
+	if (gadget->irq)
+		synchronize_irq(gadget->irq);
+	usb_gadget_udc_stop_locked(udc);
+
  err_start:
 	driver->unbind(udc->gadget);
 
-- 
2.40.0

Re: [PATCH v3 2/2] usb: gadget: udc: Handle gadget_connect failure during bind operation

[Sergei Shtylyov]

Hello!

On 5/10/23 10:52 AM, Krishna Kurapati wrote:

> In the event, gadget_connect call (which invokes pullup) fails,
> propagate the error to udc bind operation which inturn sends the
> error to configfs. The userspace can then retry enumeartion if
> it chooses to.
> 
> Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com>
> Acked-by: Alan Stern <stern@rowland.harvard.edu>
> ---
> changes in v3: Rebase on top of usb-next
> 
>  drivers/usb/gadget/udc/core.c | 21 +++++++++++++++++----
>  1 file changed, 17 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
> index 4641153e9706..69041cca5d24 100644
> --- a/drivers/usb/gadget/udc/core.c
> +++ b/drivers/usb/gadget/udc/core.c
> @@ -1122,12 +1122,16 @@ EXPORT_SYMBOL_GPL(usb_gadget_set_state);
>  /* ------------------------------------------------------------------------- */
>  
>  /* Acquire connect_lock before calling this function. */
> -static void usb_udc_connect_control_locked(struct usb_udc *udc) __must_hold(&udc->connect_lock)
> +static int usb_udc_connect_control_locked(struct usb_udc *udc) __must_hold(&udc->connect_lock)
>  {
> +	int ret;
> +
>  	if (udc->vbus && udc->started)
> -		usb_gadget_connect_locked(udc->gadget);
> +		ret = usb_gadget_connect_locked(udc->gadget);

   Why not just:

	return usb_gadget_connect_locked(udc->gadget)

>  	else
> -		usb_gadget_disconnect_locked(udc->gadget);
> +		ret = usb_gadget_disconnect_locked(udc->gadget);

   Likewise here?

> +
> +	return ret;
>  }
>  
>  /**
[...]

MBR, Sergey