ata: libata: Remove ata_noop_qc_prep()

The function ata_noop_qc_prep(), as its name implies, does nothing and
simply returns AC_ERR_OK. For drivers that do not need any special
preparations of queued commands, we can avoid having to define struct
ata_port qc_prep operation by simply testing if that operation is
defined or not in ata_qc_issue(). Make this change and remove
ata_noop_qc_prep().

Signed-off-by: Damien Le Moal <[email protected]>
Reviewed-by: John Garry <[email protected]>
Reviewed-by: Sergey Shtylyov <[email protected]>

Author: damien-lemoal

drivers/ata/libata-core.c

@@ -4696,12 +4696,6 @@ int ata_std_qc_defer(struct ata_queued_cmd *qc)
 }
 EXPORT_SYMBOL_GPL(ata_std_qc_defer);
 
-enum ata_completion_errors ata_noop_qc_prep(struct ata_queued_cmd *qc)
-{
-	return AC_ERR_OK;
-}
-EXPORT_SYMBOL_GPL(ata_noop_qc_prep);
-
 /**
  *	ata_sg_init - Associate command with scatter-gather table.
  *	@qc: Command to be associated
@@ -5088,10 +5082,13 @@ void ata_qc_issue(struct ata_queued_cmd *qc)
 		return;
 	}
 
-	trace_ata_qc_prep(qc);
-	qc->err_mask |= ap->ops->qc_prep(qc);
-	if (unlikely(qc->err_mask))
-		goto err;
+	if (ap->ops->qc_prep) {
+		trace_ata_qc_prep(qc);
+		qc->err_mask |= ap->ops->qc_prep(qc);
+		if (unlikely(qc->err_mask))
+			goto err;
+	}
+
 	trace_ata_qc_issue(qc);
 	qc->err_mask |= ap->ops->qc_issue(qc);
 	if (unlikely(qc->err_mask))
@@ -6724,7 +6721,6 @@ static void ata_dummy_error_handler(struct ata_port *ap)
 }
 
 struct ata_port_operations ata_dummy_port_ops = {
-	.qc_prep		= ata_noop_qc_prep,
 	.qc_issue		= ata_dummy_qc_issue,
 	.error_handler		= ata_dummy_error_handler,
 	.sched_eh		= ata_std_sched_eh,

drivers/ata/libata-sff.c

@@ -26,7 +26,6 @@ static struct workqueue_struct *ata_sff_wq;
 const struct ata_port_operations ata_sff_port_ops = {
 	.inherits		= &ata_base_port_ops,
 
-	.qc_prep		= ata_noop_qc_prep,
 	.qc_issue		= ata_sff_qc_issue,
 	.qc_fill_rtf		= ata_sff_qc_fill_rtf,
 

drivers/ata/pata_ep93xx.c

@@ -884,8 +884,6 @@ static const struct scsi_host_template ep93xx_pata_sht = {
 static struct ata_port_operations ep93xx_pata_port_ops = {
 	.inherits		= &ata_bmdma_port_ops,
 
-	.qc_prep		= ata_noop_qc_prep,
-
 	.softreset		= ep93xx_pata_softreset,
 	.hardreset		= ATA_OP_NULL,
 

drivers/ata/pata_icside.c

@@ -328,8 +328,6 @@ static void pata_icside_postreset(struct ata_link *link, unsigned int *classes)
 
 static struct ata_port_operations pata_icside_port_ops = {
 	.inherits		= &ata_bmdma_port_ops,
-	/* no need to build any PRD tables for DMA */
-	.qc_prep		= ata_noop_qc_prep,
 	.sff_data_xfer		= ata_sff_data_xfer32,
 	.bmdma_setup		= pata_icside_bmdma_setup,
 	.bmdma_start		= pata_icside_bmdma_start,

drivers/ata/pata_mpc52xx.c

@@ -620,7 +620,6 @@ static struct ata_port_operations mpc52xx_ata_port_ops = {
 	.bmdma_start		= mpc52xx_bmdma_start,
 	.bmdma_stop		= mpc52xx_bmdma_stop,
 	.bmdma_status		= mpc52xx_bmdma_status,
-	.qc_prep		= ata_noop_qc_prep,
 };
 
 static int mpc52xx_ata_init_one(struct device *dev,

drivers/ata/pata_octeon_cf.c

@@ -789,7 +789,6 @@ static unsigned int octeon_cf_qc_issue(struct ata_queued_cmd *qc)
 static struct ata_port_operations octeon_cf_ops = {
 	.inherits		= &ata_sff_port_ops,
 	.check_atapi_dma	= octeon_cf_check_atapi_dma,
-	.qc_prep		= ata_noop_qc_prep,
 	.qc_issue		= octeon_cf_qc_issue,
 	.sff_dev_select		= octeon_cf_dev_select,
 	.sff_irq_on		= octeon_cf_ata_port_noaction,

drivers/scsi/libsas/sas_ata.c

@@ -564,7 +564,6 @@ static struct ata_port_operations sas_sata_ops = {
 	.error_handler		= ata_std_error_handler,
 	.post_internal_cmd	= sas_ata_post_internal,
 	.qc_defer               = ata_std_qc_defer,
-	.qc_prep		= ata_noop_qc_prep,
 	.qc_issue		= sas_ata_qc_issue,
 	.qc_fill_rtf		= sas_ata_qc_fill_rtf,
 	.set_dmamode		= sas_ata_set_dmamode,

include/linux/libata.h

@@ -1168,7 +1168,6 @@ extern int ata_xfer_mode2shift(u8 xfer_mode);
 extern const char *ata_mode_string(unsigned int xfer_mask);
 extern unsigned int ata_id_xfermask(const u16 *id);
 extern int ata_std_qc_defer(struct ata_queued_cmd *qc);
-extern enum ata_completion_errors ata_noop_qc_prep(struct ata_queued_cmd *qc);
 extern void ata_sg_init(struct ata_queued_cmd *qc, struct scatterlist *sg,
 		 unsigned int n_elem);
 extern unsigned int ata_dev_classify(const struct ata_taskfile *tf);