From fbcdd80b0d5bde06f3483b9a13f9599a0452431c Mon Sep 17 00:00:00 2001 From: Albert Lee Date: Tue, 1 Nov 2005 19:30:05 +0800 Subject: [PATCH] [PATCH] libata irq-pio: eliminate unnecessary queuing in ata_pio_first_block() - change the return value of ata_pio_complete() 0 <-> 1 - add return value for ata_pio_first_block() - rename variable "qc_completed" to "has_next" in ata_pio_task() - use has_next to eliminate unnecessary queuing in ata_pio_first_block() Signed-off-by: Albert Lee ========== Signed-off-by: Jeff Garzik --- drivers/scsi/libata-core.c | 53 ++++++++++++++++++++++++-------------- 1 file changed, 33 insertions(+), 20 deletions(-) diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c index 96b8bbaa763..2e0e6cca327 100644 --- a/drivers/scsi/libata-core.c +++ b/drivers/scsi/libata-core.c @@ -2790,7 +2790,8 @@ static unsigned long ata_pio_poll(struct ata_port *ap) * None. (executing in kernel thread context) * * RETURNS: - * Non-zero if qc completed, zero otherwise. + * Zero if qc completed. + * Non-zero if has next. */ static int ata_pio_complete (struct ata_port *ap) @@ -2812,14 +2813,14 @@ static int ata_pio_complete (struct ata_port *ap) if (drv_stat & (ATA_BUSY | ATA_DRQ)) { ap->hsm_task_state = HSM_ST_LAST_POLL; ap->pio_task_timeout = jiffies + ATA_TMOUT_PIO; - return 0; + return 1; } } drv_stat = ata_wait_idle(ap); if (!ata_ok(drv_stat)) { ap->hsm_task_state = HSM_ST_ERR; - return 0; + return 1; } qc = ata_qc_from_tag(ap, ap->active_tag); @@ -2831,7 +2832,7 @@ static int ata_pio_complete (struct ata_port *ap) /* another command may start at this point */ - return 1; + return 0; } @@ -3068,27 +3069,42 @@ static void atapi_send_cdb(struct ata_port *ap, struct ata_queued_cmd *qc) * * LOCKING: * Kernel thread context (may sleep) + * + * RETURNS: + * Zero if irq handler takes over + * Non-zero if has next (polling). */ -static void ata_pio_first_block(struct ata_port *ap) +static int ata_pio_first_block(struct ata_port *ap) { struct ata_queued_cmd *qc; u8 status; unsigned long flags; + int has_next; qc = ata_qc_from_tag(ap, ap->active_tag); assert(qc != NULL); assert(qc->flags & ATA_QCFLAG_ACTIVE); + /* if polling, we will stay in the work queue after sending the data. + * otherwise, interrupt handler takes over after sending the data. + */ + has_next = (qc->tf.flags & ATA_TFLAG_POLLING); + /* sleep-wait for BSY to clear */ DPRINTK("busy wait\n"); - if (ata_busy_sleep(ap, ATA_TMOUT_DATAOUT_QUICK, ATA_TMOUT_DATAOUT)) + if (ata_busy_sleep(ap, ATA_TMOUT_DATAOUT_QUICK, ATA_TMOUT_DATAOUT)) { + ap->hsm_task_state = HSM_ST_TMOUT; goto err_out; + } /* make sure DRQ is set */ status = ata_chk_status(ap); - if ((status & (ATA_BUSY | ATA_DRQ)) != ATA_DRQ) + if ((status & (ATA_BUSY | ATA_DRQ)) != ATA_DRQ) { + /* device status error */ + ap->hsm_task_state = HSM_ST_ERR; goto err_out; + } /* Send the CDB (atapi) or the first data block (ata pio out). * During the state transition, interrupt handler shouldn't @@ -3112,18 +3128,15 @@ static void ata_pio_first_block(struct ata_port *ap) /* send CDB */ atapi_send_cdb(ap, qc); + spin_unlock_irqrestore(&ap->host_set->lock, flags); + /* if polling, ata_pio_task() handles the rest. * otherwise, interrupt handler takes over from here. */ - if (qc->tf.flags & ATA_TFLAG_POLLING) - queue_work(ata_wq, &ap->pio_task); - - spin_unlock_irqrestore(&ap->host_set->lock, flags); - - return; + return has_next; err_out: - ata_pio_error(ap); + return 1; /* has next */ } /** @@ -3338,23 +3351,23 @@ static void ata_pio_task(void *_data) { struct ata_port *ap = _data; unsigned long timeout; - int qc_completed; + int has_next; fsm_start: timeout = 0; - qc_completed = 0; + has_next = 1; switch (ap->hsm_task_state) { case HSM_ST_FIRST: - ata_pio_first_block(ap); - return; + has_next = ata_pio_first_block(ap); + break; case HSM_ST: ata_pio_block(ap); break; case HSM_ST_LAST: - qc_completed = ata_pio_complete(ap); + has_next = ata_pio_complete(ap); break; case HSM_ST_POLL: @@ -3374,7 +3387,7 @@ fsm_start: if (timeout) queue_delayed_work(ata_wq, &ap->pio_task, timeout); - else if (!qc_completed) + else if (has_next) goto fsm_start; } -- 2.39.2