On Tue, Jan 02, 2018 at 11:24:26AM +0800, Ji-Ze Hong (Peter Hong) wrote: > 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? That should be fine. Thanks for verifying. Johan -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
