[U-Boot] [PATCH 3/8] usb_kdb: only process events succesfully received

[Michal Suchánek]

On Tue, 2 Jul 2019 18:58:54 +0200
Marek Vasut <marex at denx.de> wrote:

> On 7/2/19 4:22 PM, Michal Suchánek wrote:
> > On Tue, 2 Jul 2019 15:11:07 +0200
> > Marek Vasut <marex at denx.de> wrote:
> >   
> >> On 7/2/19 3:04 PM, Michal Suchánek wrote:  
> >>> On Tue, 2 Jul 2019 13:58:30 +0200
> >>> Marek Vasut <marex at denx.de> wrote:
> >>>     
> >>>> On 7/1/19 5:56 PM, Michal Suchanek wrote:    
> >>>>> Causes unbound key repeat on error otherwise.
> >>>>>
> >>>>> Signed-off-by: Michal Suchanek <msuchanek at suse.de>
> >>>>> ---
> >>>>>  common/usb_kbd.c | 7 +++----
> >>>>>  1 file changed, 3 insertions(+), 4 deletions(-)
> >>>>>
> >>>>> diff --git a/common/usb_kbd.c b/common/usb_kbd.c
> >>>>> index cc99c6be0720..948f9fd68490 100644
> >>>>> --- a/common/usb_kbd.c
> >>>>> +++ b/common/usb_kbd.c
> >>>>> @@ -339,10 +339,9 @@ static inline void usb_kbd_poll_for_event(struct usb_device *dev)
> >>>>>  	struct usb_kbd_pdata *data = dev->privptr;
> >>>>>  
> >>>>>  	/* Submit a interrupt transfer request */
> >>>>> -	usb_submit_int_msg(dev, data->intpipe, &data->new[0], data->intpktsize,
> >>>>> -			   data->intinterval);
> >>>>> -
> >>>>> -	usb_kbd_irq_worker(dev);
> >>>>> +	if (!usb_submit_int_msg(dev, data->intpipe, &data->new[0],      
> >>>>
> >>>> Shouldn't you propagate return value from this function ? It can return
> >>>> ENOTSUPP.
> >>>>    
> >>>
> >>> If it did then probing keyboard would fail and we would not get here.    
> >>
> >> So there is no chance this function could return an error here, ever ?
> >> E.g. what if it's implemented and someone yanks the keyboard cable out
> >> just at the right time ?  
> > 
> > It returns errors all the time with dwc2. That's why we need to check
> > for the error condition. We should not get here if probing the keyboard
> > failed, though. So if the function is not supported we will not get
> > here. Anyway, if it's not supported or the keyboard is missing it by
> > definition cannot provide useful result so we should not process it.  
> 
> Except you start ignoring the error value from e.g. malfunctioning
> keyboard here, instead of propagating it, correct ?

It was never propagated to start with. The return value was not checked
at all. What I do here is check the return value and not process the
data on error whatever it contains (like the keypress returned last
time valid data was received).

Thanks

Michal