Re: [PATCH v2 1/2] usb: dwc3: gadget: Bail out in pullup if soft reset timeout happens
From: Krishna Kurapati PSSNV
Date: Tue Apr 04 2023 - 00:39:56 EST
On 4/4/2023 5:19 AM, Thinh Nguyen wrote:
On Thu, Mar 30, 2023, Krishna Kurapati PSSNV wrote:
On 3/30/2023 5:40 AM, Thinh Nguyen wrote:
On Wed, Mar 29, 2023, Krishna Kurapati PSSNV wrote:
On 3/29/2023 2:50 AM, Thinh Nguyen wrote:
Hi,
On Tue, Mar 28, 2023, Krishna Kurapati wrote:
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@xxxxxxxxxxx>
---
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 3c63fa97a680..f0472801d9a5 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2620,13 +2620,16 @@ 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, false);
}
+done:
pm_runtime_put(dwc->dev);
return ret;
--
2.40.0
I think there's one more place that may needs this check. Can you also
add this check in __dwc3_set_mode()?
Hi Thinh,
Sure. Will do it.
Will the below be good enough ? Or would it be good to add an error/warn log
there>
There's already a warning message in dwc3_core_soft_reset() if it fails.
kriskura@hu-kriskura-hyd:/local/mnt/workspace/krishna/skales2/skales/kernel$
git diff drivers/usb/
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 476b63618511..8d1d213d1dcd 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -210,7 +210,9 @@ static void __dwc3_set_mode(struct work_struct *work)
}
break;
case DWC3_GCTL_PRTCAP_DEVICE:
- dwc3_core_soft_reset(dwc);
+ ret = dwc3_core_soft_reset(dwc);
+ if (ret)
+ goto out;
dwc3_event_buffers_setup(dwc);
If soft-reset failed, the controller is in a bad state. We should not
perform any further operation until the next hard reset. We should flag
the controller as dead. I don't think we have the equivalent of the
host's HCD_FLAG_DEAD. It may require some work in the UDC core. Perhaps
we can flag within dwc3 for now and prevent any further operation for a
simpler fix.
Hi Thinh,
Are you referring that if __dwc3_set_mode failed with core soft reset
timing out, the caller i.e., dwc3_set_mode who queues the work need to know
that the operation actually failed. So we can add a flag to indicate that
gadget is dead and the caller of dwc3_set_mode can check the flag to see if
the operation is successful or not.
Or am I misunderstanding your comment ?
Not just in __dwc3_set_mode(). I mean any time dwc3_core_soft_reset
fails, then we set this flag. So that it can prevent the user calling
any gadget ops causing more crashes/invalid behavior. The
dwc->softconnect is already wrong on pullup() on failure.
So that we can have a check in different gadget ops. For pullup():
static int dwc3_gadget_pullup() {
if (dwc->udc_is_dead) {
dev_err(dev, "reset me. x_x \n");
return;
}
abc();
}
Perhaps the effort is probably the same if we enhance the UDC core for
this? In any case, I'm fine either way.
Thanks,
Thinh
Hi Thinh,
So you don't want UDC to retry pullup if it fails the first time ? As
per patch-2 of this series, I was trying to propagate the EITMEDOUT to
UDC so that the caller (most probably configfs) can take appropriate
action as to whether it must retry pullup or not.
Regards,
Krishna,