Scsi - Index of

月有关,友情,并非总与疯斗打闹有关.这几个函数应该说是给后面做铺垫,红花总要有绿叶配,没有这段代码
的铺垫,到了后面usb 设备恐怕也无法正常工作吧.不过,一个利好消息是,这几个函数我们只会遇见这一次,
它们在整个故事中就这么一次露脸的机会,像我们每个人的青春,只有一次,无法回头.和我们每个人的青春
一样,都是绝版的.所以,让我们享受这段平淡无奇的代码吧.
get_device_info, 这个函数定义于drivers/usb/storage/usb.c 中:
466 /* Get the unusual_devs entries and the string descriptors */
467 static void get_device_info(struct us_data *us, int id_index)
468 {
469 struct usb_device *dev = us->pusb_dev;
470 struct usb_interface_descriptor *idesc =
471 &us->pusb_intf->cur_altsetting->desc;
472 struct us_unusual_dev *unusual_dev = &us_unusual_dev_list[id_index];
473 struct usb_device_id *id = &storage_usb_ids[id_index];
474
475 /* Store the entries */
476 us->unusual_dev = unusual_dev;
477 us->subclass = (unusual_dev->useProtocol == US_SC_DEVICE) ?
478 idesc->bInterfaceSubClass :
479 unusual_dev->useProtocol;
480 us->protocol = (unusual_dev->useTransport == US_PR_DEVICE) ?
481 idesc->bInterfaceProtocol :
482 unusual_dev->useTransport;
483 us->flags = unusual_dev->flags;
484
485 /* Log a message if a non-generic unusual_dev entry contains an
486 * unnecessary subclass or protocol override. This may stimulate
487 * reports from users that will help us remove unneeded entries
488 * from the unusual_devs.h table.
489 */
490 if (id->idVendor || id->idProduct) {
491 static char *msgs[3] = {
492 "an unneeded SubClass entry",
493 "an unneeded Protocol entry",
494 "unneeded SubClass and Protocol entries"};
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495 struct usb_device_descriptor *ddesc = &dev->descriptor;
496 int msg = -1;
497
498 if (unusual_dev->useProtocol != US_SC_DEVICE &&
499 us->subclass == idesc->bInterfaceSubClass)
500 msg += 1;
501 if (unusual_dev->useTransport != US_PR_DEVICE &&
502 us->protocol == idesc->bInterfaceProtocol)
503 msg += 2;