On Wed, 3 Jul 2019 13:26:50 +0200 Marek Vasut <ma...@denx.de> wrote: > On 7/3/19 11:46 AM, Michal Suchánek wrote: > > On Tue, 2 Jul 2019 23:20:28 +0200 > > Marek Vasut <ma...@denx.de> wrote: > > > >> On 7/2/19 9:31 PM, Michal Suchánek wrote: > >>> On Tue, 2 Jul 2019 20:38:27 +0200 > >>> Marek Vasut <ma...@denx.de> wrote: > >>> > >>>> On 7/2/19 7:50 PM, Michal Suchánek wrote: > >>>>> On Tue, 2 Jul 2019 18:58:54 +0200 > >>>>> Marek Vasut <ma...@denx.de> wrote: > >>>>> > >>>>>> On 7/2/19 4:22 PM, Michal Suchánek wrote: > >>>>>>> On Tue, 2 Jul 2019 15:11:07 +0200 > >>>>>>> Marek Vasut <ma...@denx.de> wrote: > >>>>>>> > >>>>>>>> On 7/2/19 3:04 PM, Michal Suchánek wrote: > >>>>>>>>> On Tue, 2 Jul 2019 13:58:30 +0200 > >>>>>>>>> Marek Vasut <ma...@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 <msucha...@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). > >>>> > >>>> I can see a patch which checks usb_kbd_poll_for_event() return value. > >>>> Can you add one ? > >>> > >>> What for? Apparently the keypress is processed in usb_kbd_irq_worker. > >>> So checking the return value is needed to decide if the worker should > >>> run, and is not particularly useful outside usb_kbd_poll_for_event. We > >>> could signal a getc() failure but do we have any code handling getc() > >>> failures? > >> > >> I presume getc() might signal EOF if the underlying hardware fails. > >> But in general, it's a good practice to not ignore errors. > >> > > > > It is not such a great idea. You might have multiple input hardware (ie > > serial and usb keyboard). What does it mean that usb keyboard failed in > > this context? > > I'd say, the behavior is undefined ?
But we need to define it which the code does by ignoring the device-specific error and relying on devices that are still working (like a serial port) or for which error detection is not available (like most serial ports). > > > So in my view the ultimate consumer of getc() has no use for the error > > so there is no point in propagating it. > > Ignoring errors and not reporting them isn't nice either, so what other > option(s) do we have here ? Ignoring the errors is exactly the desirable behavior when facing broken hardware like dwc2. On non-broken hardware you will get fewer errors to ignore. It is up to the device driver to report device failure with a message when the error condition could be informative to the user (such as previously working device going away completely). Thanks Michal _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
