Re: [PATCH V2 1/5] usb: serial: f81534: add high baud rate support

[Ji-Ze Hong (Peter Hong)]

Hi Johan,

Johan Hovold æ 2018/1/10 äå 04:49 åé:
> > Normally, the communication with F81534 ep0 will take less than 1 sec
> > (even only some milliseconds), but It maybe take much long time with
> > huge loading with UART functional.
> >
> > We had tested it on BurnInTest, 4 ports with 921600bps + MSR status
> > check to perform huge loading test. The worst case to read MSR register
> > via ep0 will take 15~18 seconds. So We'll still remain the max waiting
> > time for access ep0 with 2x10=20s in high baud rate mode.
>
> Wow, that's unfortunate. But note that your patch only doubles the
> timeout to 2000 ms, that is, two seconds and not twenty:
>
> -#define F81534_USB_TIMEOUT             1000
> +#define F81534_USB_TIMEOUT             2000
>
> If you really intended to increase this to twenty seconds, then please
> do so in a separate (preparatory) patch where you describe why that is
> needed (e.g. what you wrote above).

In f81534_set_register()/f81534_get_register(), We'll use a while loop
with 10 times to get/set register and the timeout is 1000ms. So the
total minimum retry timeout is 1000x10=10s.

But when introducing the high baud rate support, 10s is not enough for
heavily loading. We had tested the minimum retry is 16~18s, so we
enlarge the F81534_USB_TIMEOUT from 1000 to 2000 and the total minimum
retry timeout is 20s.

Should I separate it as 2 patches? This issue is due to introducing
high baud patch.

Thanks
--
With Best Regards,
Peter Hong