-/*
- * Issue a new request to a drive from hwgroup
- * Caller must have already done spin_lock_irqsave(&ide_lock, ..);
- *
- * A hwgroup is a serialized group of IDE interfaces. Usually there is
- * exactly one hwif (interface) per hwgroup, but buggy controllers (eg. CMD640)
- * may have both interfaces in a single hwgroup to "serialize" access.
- * Or possibly multiple ISA interfaces can share a common IRQ by being grouped
- * together into one hwgroup for serialized access.
- *
- * Note also that several hwgroups can end up sharing a single IRQ,
- * possibly along with many other devices. This is especially common in
- * PCI-based systems with off-board IDE controller cards.
- *
- * The IDE driver uses the single global ide_lock spinlock to protect
- * access to the request queues, and to protect the hwgroup->busy flag.
- *
- * The first thread into the driver for a particular hwgroup sets the
- * hwgroup->busy flag to indicate that this hwgroup is now active,
- * and then initiates processing of the top request from the request queue.
- *
- * Other threads attempting entry notice the busy setting, and will simply
- * queue their new requests and exit immediately. Note that hwgroup->busy
- * remains set even when the driver is merely awaiting the next interrupt.
- * Thus, the meaning is "this hwgroup is busy processing a request".
- *
- * When processing of a request completes, the completing thread or IRQ-handler
- * will start the next request from the queue. If no more work remains,
- * the driver will clear the hwgroup->busy flag and exit.
- *
- * The ide_lock (spinlock) is used to protect all access to the
- * hwgroup->busy flag, but is otherwise not needed for most processing in
- * the driver. This makes the driver much more friendlier to shared IRQs
- * than previous designs, while remaining 100% (?) SMP safe and capable.
- */
-static void ide_do_request (ide_hwgroup_t *hwgroup, int masked_irq)
-{
- ide_drive_t *drive;
- ide_hwif_t *hwif;
- struct request *rq;
- ide_startstop_t startstop;
- int loops = 0;
-
- /* for atari only: POSSIBLY BROKEN HERE(?) */
- ide_get_lock(ide_intr, hwgroup);
-
- /* caller must own ide_lock */
- BUG_ON(!irqs_disabled());
-
- while (!hwgroup->busy) {
- hwgroup->busy = 1;
- drive = choose_drive(hwgroup);
- if (drive == NULL) {
- int sleeping = 0;
- unsigned long sleep = 0; /* shut up, gcc */
- hwgroup->rq = NULL;
- drive = hwgroup->drive;
- do {
- if ((drive->dev_flags & IDE_DFLAG_SLEEPING) &&
- (sleeping == 0 ||
- time_before(drive->sleep, sleep))) {
- sleeping = 1;
- sleep = drive->sleep;
- }
- } while ((drive = drive->next) != hwgroup->drive);
- if (sleeping) {
- /*
- * Take a short snooze, and then wake up this hwgroup again.
- * This gives other hwgroups on the same a chance to
- * play fairly with us, just in case there are big differences
- * in relative throughputs.. don't want to hog the cpu too much.
- */
- if (time_before(sleep, jiffies + WAIT_MIN_SLEEP))
- sleep = jiffies + WAIT_MIN_SLEEP;
-#if 1
- if (timer_pending(&hwgroup->timer))
- printk(KERN_CRIT "ide_set_handler: timer already active\n");
-#endif
- /* so that ide_timer_expiry knows what to do */
- hwgroup->sleeping = 1;
- hwgroup->req_gen_timer = hwgroup->req_gen;
- mod_timer(&hwgroup->timer, sleep);
- /* we purposely leave hwgroup->busy==1
- * while sleeping */
- } else {
- /* Ugly, but how can we sleep for the lock
- * otherwise? perhaps from tq_disk?
- */
-
- /* for atari only */
- ide_release_lock();
- hwgroup->busy = 0;
- }