[v2,2/2] usb: dwc3: Wait for control tranfer completed when stopping gadget

Message ID 3a4c91231787d31e82874161aa2ef9351f1c4b73.1473405255.git.baolin.wang@linaro.org
State New
Headers show

Commit Message

Baolin Wang Sept. 9, 2016, 7:16 a.m.
When we change the USB function with configfs dynamically, we possibly met this
situation: one core is doing the control transfer, another core is trying to
unregister the USB gadget from userspace, we must wait for completing this
control tranfer, or it will hang the controller to set the DEVCTRLHLT flag.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>

---
 drivers/usb/dwc3/core.c   |    1 +
 drivers/usb/dwc3/core.h   |    2 ++
 drivers/usb/dwc3/ep0.c    |    2 ++
 drivers/usb/dwc3/gadget.c |   21 +++++++++++++++++++++
 4 files changed, 26 insertions(+)

-- 
1.7.9.5

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Comments

Baolin Wang Sept. 18, 2016, 4:58 a.m. | #1
Hi Felipe,

On 9 September 2016 at 19:03, Felipe Balbi <balbi@kernel.org> wrote:
>

> Hi,

>

> Baolin Wang <baolin.wang@linaro.org> writes:

>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c

>> index 057739d..22787b6 100644

>> --- a/drivers/usb/dwc3/core.c

>> +++ b/drivers/usb/dwc3/core.c

>> @@ -999,6 +999,7 @@ static int dwc3_probe(struct platform_device *pdev)

>>               goto err0;

>>

>>       spin_lock_init(&dwc->lock);

>> +     init_completion(&dwc->ep0_completed);

>

> this should be done only when gadget is required; meaning that this

> should be moved to dwc3_gadget_init()


OK.

>

>> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h

>> index b2317e7..858e661 100644

>> --- a/drivers/usb/dwc3/core.h

>> +++ b/drivers/usb/dwc3/core.h

>

> [...]

>

>> @@ -843,6 +844,7 @@ struct dwc3 {

>>       dma_addr_t              ep0_bounce_addr;

>>       dma_addr_t              scratch_addr;

>>       struct dwc3_request     ep0_usb_req;

>> +     struct completion       ep0_completed;

>

> when you call this "ep0_completed" it seems like you're defining a flag,

> but you're not :) How about "ep0_in_setup" instead? That conveys the

> idea that we're waiting for ep0 to reach setup phase.


Make sense and will change it.

>

>> diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c

>> index 632e5a4..baf932d 100644

>> --- a/drivers/usb/dwc3/ep0.c

>> +++ b/drivers/usb/dwc3/ep0.c

>> @@ -286,6 +286,7 @@ static void dwc3_ep0_stall_and_restart(struct dwc3 *dwc)

>>

>>       dwc->ep0state = EP0_SETUP_PHASE;

>>       dwc3_ep0_out_start(dwc);

>> +     complete(&dwc->ep0_completed);

>

> no, this is wrong. I see what you're trying to do here, but we don't

> want to duplicate this call to complete() right? One thing we can

> realize is that *always* after STATUS phase or after a STALL, we will go

> through dwc3_ep0_out_start(), this mean we can call complete() before

> starting the following SETUP phase.

>

> Single place to call complete() ;-)


Make sense to me and I will fix that in next version.

>

>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c

>> index 1a33308..c9026ce 100644

>> --- a/drivers/usb/dwc3/gadget.c

>> +++ b/drivers/usb/dwc3/gadget.c

>> @@ -1441,6 +1441,15 @@ static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on, int suspend)

>>       if (pm_runtime_suspended(dwc->dev))

>>               return 0;

>>

>> +     /*

>> +      * Per databook, when we want to stop the gadget, if a control transfer

>> +      * is still in process, complete it and get the core into setup phase.

>> +      */

>> +     if (!is_on && dwc->ep0state != EP0_SETUP_PHASE) {

>> +             reinit_completion(&dwc->ep0_completed);

>

> this seems unnecessary to me. Also, why return here so the caller has to


We should re-init the completion due to it will complete control
transfer many times before we try to stop gadget.

> wait? You could just have called wait_for_completion() here straight

> away:

>

>         if (!is_on && dwc->ep0state != EP0_SETUP_PHASE) {

>                 /* should this be interruptible? */

>                 ret = wait_for_completion_timeout(&dwc->ep0_in_setup,

>                                 msecs_to_jiffies(500));

>                 if (ret == 0) {

>                         dwc3_trace(trace_dwc3_gadget, "RUN/STOP timeout");

>                         return -ETIMEDOUT;

>                 }

>         }

>

> There's also no need for that "try_again" trickery. We either can halt

> the controller within 500ms or we cannot.


But this is in atomic context and we can not issue
wait_for_completion_timeout() in atomic context, then we should just
return here.

-- 
Baolin.wang
Best Regards
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Baolin Wang Sept. 19, 2016, 10:42 a.m. | #2
Hi Felipe,

On 19 September 2016 at 17:58, Felipe Balbi <balbi@kernel.org> wrote:
>

> Hi,

>

> Baolin Wang <baolin.wang@linaro.org> writes:

>>>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c

>>>> index 1a33308..c9026ce 100644

>>>> --- a/drivers/usb/dwc3/gadget.c

>>>> +++ b/drivers/usb/dwc3/gadget.c

>>>> @@ -1441,6 +1441,15 @@ static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on, int suspend)

>>>>       if (pm_runtime_suspended(dwc->dev))

>>>>               return 0;

>>>>

>>>> +     /*

>>>> +      * Per databook, when we want to stop the gadget, if a control transfer

>>>> +      * is still in process, complete it and get the core into setup phase.

>>>> +      */

>>>> +     if (!is_on && dwc->ep0state != EP0_SETUP_PHASE) {

>>>> +             reinit_completion(&dwc->ep0_completed);

>>>

>>> this seems unnecessary to me. Also, why return here so the caller has to

>>

>> We should re-init the completion due to it will complete control

>> transfer many times before we try to stop gadget.

>

> not sure I get this comment, care to furter explain what you mean?


Sorry for confusing comment. What I mean is it will issue
'complete(&dwc->ep0_completed)' when one control transfer is
completed, and it will increase the completion->done when every
'complete()' function is issued.

If there are seveal control transfers are completed (completion->done
is not 0 bow) and dwc->ep0state is not in EP0_SETUP_PHASE satus when
we want to stop gadget, then we should wait for completion. If we
don't call 'reinit_completion(&dwc->ep0_completed)' (it will reset
completion->done as 0 ), it will not wait for 500ms in
wait_for_completion_timeout() funtion. Hope I make it clear.

>

>>> wait? You could just have called wait_for_completion() here straight

>>> away:

>>>

>>>         if (!is_on && dwc->ep0state != EP0_SETUP_PHASE) {

>>>                 /* should this be interruptible? */

>>>                 ret = wait_for_completion_timeout(&dwc->ep0_in_setup,

>>>                                 msecs_to_jiffies(500));

>>>                 if (ret == 0) {

>>>                         dwc3_trace(trace_dwc3_gadget, "RUN/STOP timeout");

>>>                         return -ETIMEDOUT;

>>>                 }

>>>         }

>>>

>>> There's also no need for that "try_again" trickery. We either can halt

>>> the controller within 500ms or we cannot.

>>

>> But this is in atomic context and we can not issue

>> wait_for_completion_timeout() in atomic context, then we should just

>> return here.

>

> heh, good point. Missed that :-)


OK:)

-- 
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Patch hide | download patch | download mbox

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 057739d..22787b6 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -999,6 +999,7 @@  static int dwc3_probe(struct platform_device *pdev)
 		goto err0;
 
 	spin_lock_init(&dwc->lock);
+	init_completion(&dwc->ep0_completed);
 
 	if (!dev->dma_mask) {
 		dev->dma_mask = dev->parent->dma_mask;
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index b2317e7..858e661 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -745,6 +745,7 @@  struct dwc3_scratchpad_array {
  * @ep0_usb_req: dummy req used while handling STD USB requests
  * @ep0_bounce_addr: dma address of ep0_bounce
  * @scratch_addr: dma address of scratchbuf
+ * @ep0_completed: One control tranfer is completed
  * @lock: for synchronizing
  * @dev: pointer to our struct device
  * @xhci: pointer to our xHCI child
@@ -843,6 +844,7 @@  struct dwc3 {
 	dma_addr_t		ep0_bounce_addr;
 	dma_addr_t		scratch_addr;
 	struct dwc3_request	ep0_usb_req;
+	struct completion	ep0_completed;
 
 	/* device lock */
 	spinlock_t		lock;
diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
index 632e5a4..baf932d 100644
--- a/drivers/usb/dwc3/ep0.c
+++ b/drivers/usb/dwc3/ep0.c
@@ -286,6 +286,7 @@  static void dwc3_ep0_stall_and_restart(struct dwc3 *dwc)
 
 	dwc->ep0state = EP0_SETUP_PHASE;
 	dwc3_ep0_out_start(dwc);
+	complete(&dwc->ep0_completed);
 }
 
 int __dwc3_gadget_ep0_set_halt(struct usb_ep *ep, int value)
@@ -935,6 +936,7 @@  static void dwc3_ep0_complete_status(struct dwc3 *dwc,
 
 	dwc->ep0state = EP0_SETUP_PHASE;
 	dwc3_ep0_out_start(dwc);
+	complete(&dwc->ep0_completed);
 }
 
 static void dwc3_ep0_xfer_complete(struct dwc3 *dwc,
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 1a33308..c9026ce 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1441,6 +1441,15 @@  static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on, int suspend)
 	if (pm_runtime_suspended(dwc->dev))
 		return 0;
 
+	/*
+	 * Per databook, when we want to stop the gadget, if a control transfer
+	 * is still in process, complete it and get the core into setup phase.
+	 */
+	if (!is_on && dwc->ep0state != EP0_SETUP_PHASE) {
+		reinit_completion(&dwc->ep0_completed);
+		return -EBUSY;
+	}
+
 	reg = dwc3_readl(dwc->regs, DWC3_DCTL);
 	if (is_on) {
 		if (dwc->revision <= DWC3_REVISION_187A) {
@@ -1491,10 +1500,22 @@  static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
 
 	is_on = !!is_on;
 
+try_again:
 	spin_lock_irqsave(&dwc->lock, flags);
 	ret = dwc3_gadget_run_stop(dwc, is_on, false);
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
+	if (ret == -EBUSY) {
+		ret = wait_for_completion_timeout(&dwc->ep0_completed,
+						  msecs_to_jiffies(100));
+		if (ret == 0) {
+			dev_err(dwc->dev, "timeout to stop gadget.\n");
+			return -ETIMEDOUT;
+		} else {
+			goto try_again;
+		}
+	}
+
 	return ret;
 }