Hi Johan, Johan Hovold 於 2017/12/19 上午 12:06 寫道:
On Thu, Nov 16, 2017 at 03:46:08PM +0800, Ji-Ze Hong (Peter Hong) wrote:+static int f81534_set_port_output_pin(struct usb_serial_port *port) +{ + struct f81534_serial_private *serial_priv; + struct f81534_port_private *port_priv; + struct usb_serial *serial; + const struct f81534_port_out_pin *pins; + int status; + int i; + u8 value; + u8 idx; + + serial = port->serial; + serial_priv = usb_get_serial_data(serial); + port_priv = usb_get_serial_port_data(port); + + idx = F81534_CONF_GPIO_OFFSET + port_priv->phy_num; + value = serial_priv->conf_data[idx]; + pins = &f81534_port_out_pins[port_priv->phy_num]; + + for (i = 0; i < ARRAY_SIZE(pins->pin); ++i) { + status = f81534_set_mask_register(serial, + pins->pin[i].reg_addr, pins->pin[i].reg_mask, + value & BIT(i) ? pins->pin[i].reg_mask : 0); + if (status) + return status; + }You're using 24 (get or set) accesses to update these three registers here. Why not read them out (if necessary), determine their new values and then write them back when done instead?
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? Thanks -- With Best Regards, Peter Hong -- 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
