Re: [PATCH V1 3/4] usb: serial: f81534: add output pin control

[Ji-Ze Hong (Peter Hong)]

Hi Johan,

> > In this code, I'm only read/write 3 registers of 0x2ae8, 0x2a90, 0x2a80,
> > but some register will read/write more than once. Should I change the
> > code from port_probe() to attach() and re-write it as:
> > 	1: read the 3 register
> > 	2: change them will 12 pin desire value
> > 	3: write it back
> > Is it ok?
>
> Do you expect these pins to ever be changed after probe? If not, then
> perhaps it can be moved to attach(), but otherwise I guess they should
> be set at port_probe(). By using shadow registers, you should be able to
> reduce the number of device accesses, but perhaps it's not worth the
> complexity.
>
> Do you have a rough idea about how long these register updates take? I
> was just worried that these changes will add up to really long probe
> times.

I had measured the time of the loop in f81534_set_port_output_pin() via
getnstimeofday() with 685.410 ~ 3681.682us per port, but normally with
600~800us per port. So I prefer remain the current method of
f81534_set_port_output_pin(). Is it ok?

Thanks
--
With Best Regards,
Peter Hong