linux-kernel - Re: [PATCH v4 01/13] USB: ch341: fix error handling on resume

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Date:	Fri, 29 Apr 2016 17:11:13 +0200
From:	Grigori Goronzy <greg@...wn.ath.cx>
To:	Johan Hovold <johan@...nel.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	Johan Hovold <jhovold@...il.com>
Subject: Re: [PATCH v4 01/13] USB: ch341: fix error handling on resume

On 2016-04-29 14:16, Johan Hovold wrote:
> On Fri, Apr 15, 2016 at 11:14:04PM +0200, Grigori Goronzy wrote:
>> This may fail, do not assume it always works.
>> 
>> Signed-off-by: Grigori Goronzy <greg@...wn.ath.cx>
>> ---
>>  drivers/usb/serial/ch341.c | 4 +---
>>  1 file changed, 1 insertion(+), 3 deletions(-)
>> 
>> diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
>> index c73808f..63df8ce 100644
>> --- a/drivers/usb/serial/ch341.c
>> +++ b/drivers/usb/serial/ch341.c
>> @@ -544,9 +544,7 @@ static int ch341_reset_resume(struct usb_serial 
>> *serial)
>>  	priv = usb_get_serial_port_data(serial->port[0]);
>> 
>>  	/* reconfigure ch341 serial port after bus-reset */
>> -	ch341_configure(serial->dev, priv);
>> -
>> -	return 0;
>> +	return ch341_configure(serial->dev, priv);
> 
> This is correct, but have noticed that resume is currently broken in
> that the interrupt urb is never resubmitted on resume in case the port 
> is
> already open?
> 
> Also ch341_configure must not use GFP_KERNEL either if called from a
> resume path (use GFP_NOIO).
> 
> Care to fix this up as well?
> 

Sure. How can I trigger a reset properly? AFAIR, I tried USBDEVFS_RESET 
and it didn't really do what I wanted, at least the reset_resume 
callback wasn't invoked.

Grigori