[RFC] Move the calling of usb_serial_register() from individual driver into usb_serial_probe()

[Huajun Li <huajun.li.lee@xxxxxxxxx>]

Hi ,
While working on a new USB serial driver, I find it need call
usb_serial_register() to register a serial driver, then call
usb_register() to register the USB one. So calling
usb_serial_register() is common for most of USB serial drivers,
moreover, these drivers are using usb_searil_probe() to probe the USB
devices. Then, how about move the calling of usb_serial_register()
from these modules' init routine into usb_serial_probe() ?

>From logical side, maybe it is reasonable:  While initiating  the
module, it only registers a USB driver as what other usual USB drivers
do, and passes the customized serial driver information through
'driver_info'.  When the driver does probing, it can retrieve serial
driver information from 'driver_info' to registers a serial driver to
system in order to talk with other subsystem.

Does this changes make sense to go ahead ?

BTW, following is a draft patch to show the changes taking pl2303.c as
an example:

--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -37,62 +37,63 @@
 #define DRIVER_DESC "Prolific PL2303 USB to serial adaptor driver"

 static int debug;
+static struct usb_serial_driver pl2303_device;

 #define PL2303_CLOSING_WAIT    (30*HZ)

 static const struct usb_device_id id_table[] = {
-       { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID) },
+       { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID),
.driver_info = (unsigned long)&pl2303_device },
@@ -859,24 +860,18 @@ static int __init pl2303_init(void)
 {
        int retval;

-       retval = usb_serial_register(&pl2303_device);
-       if (retval)
-               goto failed_usb_serial_register;
        retval = usb_register(&pl2303_driver);
        if (retval)
                goto failed_usb_register;
        printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_DESC "\n");
        return 0;
 failed_usb_register:
-       usb_serial_deregister(&pl2303_device);
-failed_usb_serial_register:
        return retval;
 }

 static void __exit pl2303_exit(void)
 {
        usb_deregister(&pl2303_driver);
-       usb_serial_deregister(&pl2303_device);
 }

 module_init(pl2303_init);

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index cc274fd..c60147b4 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -731,14 +731,16 @@ int usb_serial_probe(struct usb_interface *interface,
        int num_ports = 0;
        int max_endpoints;

-       mutex_lock(&table_lock);
-       type = search_serial_device(interface);
+        type = (struct usb_serial_driver *)id->driver_info;
        if (!type) {
-               mutex_unlock(&table_lock);
                dbg("none matched");
                return -ENODEV;
        }

+       usb_serial_register(type);
+
+       mutex_lock(&table_lock);
        if (!try_module_get(type->driver.owner)) {
                mutex_unlock(&table_lock);
                dev_err(&interface->dev, "module get failed, exiting\n");
@@ -1146,6 +1148,11 @@ void usb_serial_disconnect(struct usb_interface
*interface)

        /* let the last holder of this object cause it to be cleaned up */
        usb_serial_put(serial);
+
+       struct usb_serial_driver * drv = search_serial_device(interface);
+       if (drv)
+               usb_serial_deregister(drv);
+
        dev_info(dev, "device disconnected\n");
 }
 EXPORT_SYMBOL_GPL(usb_serial_disconnect);
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