linux-kernel - Re: [RFC 2/2] usb: gadget: udc: Handle gadget

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Message-ID: <33e7f57d-b3f3-b4cb-b466-49c0eeb28191@quicinc.com>
Date:   Wed, 22 Mar 2023 21:03:17 +0530
From:   Krishna Kurapati PSSNV <quic_kriskura@...cinc.com>
To:     Alan Stern <stern@...land.harvard.edu>
CC:     Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        "Geert Uytterhoeven" <geert+renesas@...der.be>,
        Sebastian Reichel <sre@...nel.org>,
        Colin Ian King <colin.i.king@...il.com>,
        Jiantao Zhang <water.zhangjiantao@...wei.com>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <quic_ppratap@...cinc.com>, <quic_wcheng@...cinc.com>,
        <quic_jackp@...cinc.com>, <quic_ugoswami@...cinc.com>
Subject: Re: [RFC 2/2] usb: gadget: udc: Handle gadget_connect failure during
 bind operation



On 3/22/2023 8:11 PM, Alan Stern wrote:
> On Wed, Mar 22, 2023 at 02:57:40PM +0530, 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@...cinc.com>
>> ---
>>   drivers/usb/gadget/udc/core.c | 17 +++++++++++++----
>>   1 file changed, 13 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c
>> index 23b0629a8774..26bfed5c3a45 100644
>> --- a/drivers/usb/gadget/udc/core.c
>> +++ b/drivers/usb/gadget/udc/core.c
>> @@ -1051,12 +1051,16 @@ EXPORT_SYMBOL_GPL(usb_gadget_set_state);
>>   
>>   /* ------------------------------------------------------------------------- */
>>   
>> -static void usb_udc_connect_control(struct usb_udc *udc)
>> +static int usb_udc_connect_control(struct usb_udc *udc)
>>   {
>> +	int ret;
>> +
>>   	if (udc->vbus)
>> -		usb_gadget_connect(udc->gadget);
>> +		ret = usb_gadget_connect(udc->gadget);
>>   	else
>> -		usb_gadget_disconnect(udc->gadget);
>> +		ret = usb_gadget_disconnect(udc->gadget);
>> +
>> +	return ret;
>>   }
>>   
>>   /**
>> @@ -1500,11 +1504,16 @@ static int gadget_bind_driver(struct device *dev)
>>   	if (ret)
>>   		goto err_start;
>>   	usb_gadget_enable_async_callbacks(udc);
>> -	usb_udc_connect_control(udc);
>> +	ret = usb_udc_connect_control(udc);
>> +	if (ret)
>> +		goto err_connect_control;
>>   
>>   	kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
>>   	return 0;
>>   
>> + err_connect_control:
> 
> At this point you need to copy the code in gadget_unbind_driver().  In
> particular, this should have:
> 
> +	usb_gadget_disable_async_callbacks(udc);
> +	if (gadget->irq)
> +		synchronize_irq(gadget->irq);
> 
> Alan Stern
> 
>> +	usb_gadget_udc_stop(udc);
>> +
>>    err_start:
>>   	driver->unbind(udc->gadget);
>>   
>> -- 
>> 2.40.0
>>
Hi Alan,

  Thanks for the review. Will make sure to add it in the formal patch.

Regards,
Krishna,