linux-kernel - Re: [PATCH v2 1/2] usb: dwc3: gadget: Bail out in pullup if soft reset timeout happens

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Date:   Wed, 29 Mar 2023 10:04:47 +0530
From:   Krishna Kurapati PSSNV <quic_kriskura@...cinc.com>
To:     Thinh Nguyen <Thinh.Nguyen@...opsys.com>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alan Stern <stern@...land.harvard.edu>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Colin Ian King <colin.i.king@...il.com>,
        Jiantao Zhang <water.zhangjiantao@...wei.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "quic_ppratap@...cinc.com" <quic_ppratap@...cinc.com>,
        "quic_wcheng@...cinc.com" <quic_wcheng@...cinc.com>,
        "quic_jackp@...cinc.com" <quic_jackp@...cinc.com>,
        "quic_ugoswami@...cinc.com" <quic_ugoswami@...cinc.com>
Subject: Re: [PATCH v2 1/2] usb: dwc3: gadget: Bail out in pullup if soft
 reset timeout happens



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@...cinc.com>
>> ---
>>   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>

kriskura@...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);

Regards,
Krishna,