libata: separate out ata_std_prereset() from ata_sff_prereset()

Separate out generic ATA portion from ata_sff_prereset() into
ata_std_prereset() and implement ata_sff_prereset() using the std
version.  Waiting for device readiness is the only SFF specific part.

ata_base_port_ops now has ata_std_prereset() for its prereset and
ata_sff_port_ops overrides it to ata_sff_prereset().  This change can
affect pdc_adma, ahci, sata_fsl and sata_sil24.  pdc_adma implements
its own prereset using ata_sff_prereset() and the rest has hardreset
and thus are unaffected by this change.

This change reflects real world situation.  There is no generic way to
wait for device readiness for non-SFF controllers and some of them
don't have any mechanism for that.  Non-sff drivers which don't have
hardreset should wrap ata_std_prereset() and wait for device readiness
itself but there's no such driver now and isn't likely to be popular
in the future either.

Signed-off-by: Tejun Heo <htejun@gmail.com>
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index fd912cc..5f771bb 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -74,7 +74,7 @@
 const unsigned long sata_deb_timing_long[]		= { 100, 2000, 5000 };
 
 const struct ata_port_operations ata_base_port_ops = {
-	.prereset		= ata_sff_prereset,
+	.prereset		= ata_std_prereset,
 	.hardreset		= sata_sff_hardreset,
 	.postreset		= ata_sff_postreset,
 	.error_handler		= ata_std_error_handler,
@@ -3416,7 +3416,7 @@
 }
 
 /**
- *	ata_sff_prereset - prepare for reset
+ *	ata_std_prereset - prepare for reset
  *	@link: ATA link to be reset
  *	@deadline: deadline jiffies for the operation
  *
@@ -3432,7 +3432,7 @@
  *	RETURNS:
  *	0 on success, -errno otherwise.
  */
-int ata_sff_prereset(struct ata_link *link, unsigned long deadline)
+int ata_std_prereset(struct ata_link *link, unsigned long deadline)
 {
 	struct ata_port *ap = link->ap;
 	struct ata_eh_context *ehc = &link->eh_context;
@@ -3452,16 +3452,6 @@
 					"link for reset (errno=%d)\n", rc);
 	}
 
-	/* wait for !BSY if we don't know that no device is attached */
-	if (!ata_link_offline(link)) {
-		rc = ata_sff_wait_ready(ap, deadline);
-		if (rc && rc != -ENODEV) {
-			ata_link_printk(link, KERN_WARNING, "device not ready "
-					"(errno=%d), forcing hardreset\n", rc);
-			ehc->i.action |= ATA_EH_HARDRESET;
-		}
-	}
-
 	return 0;
 }
 
@@ -6104,6 +6094,7 @@
 EXPORT_SYMBOL_GPL(sata_set_spd);
 EXPORT_SYMBOL_GPL(sata_link_debounce);
 EXPORT_SYMBOL_GPL(sata_link_resume);
+EXPORT_SYMBOL_GPL(ata_std_prereset);
 EXPORT_SYMBOL_GPL(sata_link_hardreset);
 EXPORT_SYMBOL_GPL(ata_dev_classify);
 EXPORT_SYMBOL_GPL(ata_dev_pair);