[PATCH 4/7] libata: use freeze/thaw for polling PIO

[Albert Lee <albertcc@tw.ibm.com>]

This patch let polling pio codes to use freeze()/thaw() for irq off/on.
The reason is: some ATAPI devices raises INTRQ even of nIEN = 1.
Using the host adapter irq mask mechanism, if available, is more reliable than the device nIEN bit.

ata_qc_set_polling() is also removed since now unused.

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>
---
Considerations:
Polling PIO, the new user of freeze()/thaw(), might have higher calling frequency to freeze()/thaw() than EH.
Can current implemention of freeze()/thaw() handle that?
We might need more testing on sata_nv, sata_promise, sata_sil, sata_sil24, sata_via and sata_vsc.


diff -Nrup 03_add_thaw_freeze/drivers/ata/libata-core.c 04_use_freeze_polling/drivers/ata/libata-core.c
--- 03_add_thaw_freeze/drivers/ata/libata-core.c	2007-07-07 10:38:55.000000000 +0800
+++ 04_use_freeze_polling/drivers/ata/libata-core.c	2007-07-07 10:40:10.000000000 +0800
@@ -4753,7 +4753,7 @@ static void ata_hsm_qc_complete(struct a
 			qc = ata_qc_from_tag(ap, qc->tag);
 			if (qc) {
 				if (likely(!(qc->err_mask & AC_ERR_HSM))) {
-					ap->ops->irq_on(ap);
+					ap->ops->thaw(ap);
 					ata_qc_complete(qc);
 				} else
 					ata_port_freeze(ap);
@@ -4769,7 +4769,7 @@ static void ata_hsm_qc_complete(struct a
 	} else {
 		if (in_wq) {
 			spin_lock_irqsave(ap->lock, flags);
-			ap->ops->irq_on(ap);
+			ap->ops->thaw(ap);
 			ata_qc_complete(qc);
 			spin_unlock_irqrestore(ap->lock, flags);
 		} else
@@ -5411,7 +5411,7 @@ unsigned int ata_qc_issue_prot(struct at
 	switch (qc->tf.protocol) {
 	case ATA_PROT_NODATA:
 		if (qc->tf.flags & ATA_TFLAG_POLLING)
-			ata_qc_set_polling(qc);
+			ap->ops->freeze(ap);
 
 		ata_tf_to_host(ap, &qc->tf);
 		ap->hsm_task_state = HSM_ST_LAST;
@@ -5432,7 +5432,7 @@ unsigned int ata_qc_issue_prot(struct at
 
 	case ATA_PROT_PIO:
 		if (qc->tf.flags & ATA_TFLAG_POLLING)
-			ata_qc_set_polling(qc);
+			ap->ops->freeze(ap);
 
 		ata_tf_to_host(ap, &qc->tf);
 
@@ -5461,7 +5461,7 @@ unsigned int ata_qc_issue_prot(struct at
 	case ATA_PROT_ATAPI:
 	case ATA_PROT_ATAPI_NODATA:
 		if (qc->tf.flags & ATA_TFLAG_POLLING)
-			ata_qc_set_polling(qc);
+			ap->ops->freeze(ap);
 
 		ata_tf_to_host(ap, &qc->tf);
 
diff -Nrup 03_add_thaw_freeze/include/linux/libata.h 04_use_freeze_polling/include/linux/libata.h
--- 03_add_thaw_freeze/include/linux/libata.h	2007-07-07 09:59:42.000000000 +0800
+++ 04_use_freeze_polling/include/linux/libata.h	2007-07-07 10:40:10.000000000 +0800
@@ -1094,11 +1094,6 @@ static inline u8 ata_wait_idle(struct at
 	return status;
 }
 
-static inline void ata_qc_set_polling(struct ata_queued_cmd *qc)
-{
-	qc->tf.ctl |= ATA_NIEN;
-}
-
 static inline struct ata_queued_cmd *__ata_qc_from_tag(struct ata_port *ap,
 						       unsigned int tag)
 {