ide: call ide_build_sglist() prior to ->dma_setup (v2)

* Re-map sg table if needed in ide_build_sglist().

* Move ide_build_sglist() call from ->dma_setup to its users.

* Un-export ide_build_sglist().

v2:
* Build fix for CONFIG_BLK_DEV_IDEDMA=n (noticed by Randy Dunlap).

There should be no functional changes caused by this patch.

Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/au1xxx-ide.c

@@ -211,21 +211,16 @@ static void auide_set_dma_mode(ide_drive_t *drive, const u8 speed)
 #ifdef CONFIG_BLK_DEV_IDE_AU1XXX_MDMA2_DBDMA
 static int auide_build_dmatable(ide_drive_t *drive)
 {
-	int i, iswrite, count = 0;
 	ide_hwif_t *hwif = drive->hwif;
 	struct request *rq = hwif->rq;
 	_auide_hwif *ahwif = &auide_hwif;
 	struct scatterlist *sg;
+	int i = hwif->sg_nents, iswrite, count = 0;
 
 	iswrite = (rq_data_dir(rq) == WRITE);
 	/* Save for interrupt context */
 	ahwif->drive = drive;
 
-	hwif->sg_nents = i = ide_build_sglist(drive, rq);
-
-	if (!i)
-		return 0;
-
 	/* fill the descriptors */
 	sg = hwif->sg_table;
 	while (i && sg_dma_len(sg)) {

drivers/ide/icside.c

@@ -325,12 +325,6 @@ static int icside_dma_setup(ide_drive_t *drive)
 	 */
 	BUG_ON(dma_channel_active(ec->dma));
 
-	hwif->sg_nents = ide_build_sglist(drive, rq);
-	if (hwif->sg_nents == 0) {
-		ide_map_sg(drive, rq);
-		return 1;
-	}
-
 	/*
 	 * Ensure that we have the right interrupt routed.
 	 */

drivers/ide/ide-atapi.c

@@ -631,18 +631,23 @@ ide_startstop_t ide_issue_pc(ide_drive_t *drive)
 	struct ide_atapi_pc *pc;
 	ide_hwif_t *hwif = drive->hwif;
 	ide_expiry_t *expiry = NULL;
+	struct request *rq = hwif->rq;
 	unsigned int timeout;
 	u32 tf_flags;
 	u16 bcount;
 
 	if (dev_is_idecd(drive)) {
 		tf_flags = IDE_TFLAG_OUT_NSECT | IDE_TFLAG_OUT_LBAL;
-		bcount = ide_cd_get_xferlen(hwif->rq);
+		bcount = ide_cd_get_xferlen(rq);
 		expiry = ide_cd_expiry;
 		timeout = ATAPI_WAIT_PC;
 
-		if (drive->dma)
+		if (drive->dma) {
-			drive->dma = !hwif->dma_ops->dma_setup(drive);
+			if (ide_build_sglist(drive, rq))
+				drive->dma = !hwif->dma_ops->dma_setup(drive);
+			else
+				drive->dma = 0;
+		}
 	} else {
 		pc = drive->pc;
 
@@ -661,8 +666,12 @@ ide_startstop_t ide_issue_pc(ide_drive_t *drive)
 		}
 
 		if ((pc->flags & PC_FLAG_DMA_OK) &&
-		     (drive->dev_flags & IDE_DFLAG_USING_DMA))
+		     (drive->dev_flags & IDE_DFLAG_USING_DMA)) {
-			drive->dma = !hwif->dma_ops->dma_setup(drive);
+			if (ide_build_sglist(drive, rq))
+				drive->dma = !hwif->dma_ops->dma_setup(drive);
+			else
+				drive->dma = 0;
+		}
 
 		if (!drive->dma)
 			pc->flags &= ~PC_FLAG_DMA_OK;

drivers/ide/ide-dma-sff.c

@@ -120,10 +120,6 @@ int ide_build_dmatable(ide_drive_t *drive, struct request *rq)
 	struct scatterlist *sg;
 	u8 is_trm290 = !!(hwif->host_flags & IDE_HFLAG_TRM290);
 
-	hwif->sg_nents = ide_build_sglist(drive, rq);
-	if (hwif->sg_nents == 0)
-		return 0;
-
 	for_each_sg(hwif->sg_table, sg, hwif->sg_nents, i) {
 		u32 cur_addr, cur_len, xcount, bcount;
 

drivers/ide/ide-dma.c

@@ -138,14 +138,15 @@ int ide_build_sglist(ide_drive_t *drive, struct request *rq)
 		hwif->sg_dma_direction = DMA_TO_DEVICE;
 
 	i = dma_map_sg(hwif->dev, sg, hwif->sg_nents, hwif->sg_dma_direction);
-	if (i) {
+	if (i == 0)
+		ide_map_sg(drive, rq);
+	else {
 		hwif->orig_sg_nents = hwif->sg_nents;
 		hwif->sg_nents = i;
 	}
 
 	return i;
 }
-EXPORT_SYMBOL_GPL(ide_build_sglist);
 
 /**
  *	ide_destroy_dmatable	-	clean up DMA mapping

drivers/ide/ide-taskfile.c

@@ -103,6 +103,7 @@ ide_startstop_t do_rw_taskfile (ide_drive_t *drive, ide_task_t *task)
 		return ide_started;
 	default:
 		if ((drive->dev_flags & IDE_DFLAG_USING_DMA) == 0 ||
+		    ide_build_sglist(drive, hwif->rq) == 0 ||
 		    dma_ops->dma_setup(drive))
 			return ide_stopped;
 		dma_ops->dma_exec_cmd(drive, tf->command);

drivers/ide/pmac.c

@@ -1429,10 +1429,10 @@ pmac_ide_build_dmatable(ide_drive_t *drive, struct request *rq)
 	pmac_ide_hwif_t *pmif =
 		(pmac_ide_hwif_t *)dev_get_drvdata(hwif->gendev.parent);
 	struct dbdma_cmd *table;
-	int i, count = 0;
 	volatile struct dbdma_regs __iomem *dma = pmif->dma_regs;
 	struct scatterlist *sg;
 	int wr = (rq_data_dir(rq) == WRITE);
+	int i = hwif->sg_nents, count = 0;
 
 	/* DMA table is already aligned */
 	table = (struct dbdma_cmd *) pmif->dma_table_cpu;
@@ -1442,11 +1442,6 @@ pmac_ide_build_dmatable(ide_drive_t *drive, struct request *rq)
 	while (readl(&dma->status) & RUN)
 		udelay(1);
 
-	hwif->sg_nents = i = ide_build_sglist(drive, rq);
-
-	if (!i)
-		return 0;
-
 	/* Build DBDMA commands list */
 	sg = hwif->sg_table;
 	while (i && sg_dma_len(sg)) {

drivers/ide/sgiioc4.c

@@ -429,15 +429,9 @@ sgiioc4_build_dma_table(ide_drive_t * drive, struct request *rq, int ddir)
 {
 	ide_hwif_t *hwif = drive->hwif;
 	unsigned int *table = hwif->dmatable_cpu;
-	unsigned int count = 0, i = 1;
+	unsigned int count = 0, i = hwif->sg_nents;
-	struct scatterlist *sg;
+	struct scatterlist *sg = hwif->sg_table;
 
-	hwif->sg_nents = i = ide_build_sglist(drive, rq);
-
-	if (!i)
-		return 0;	/* sglist of length Zero */
-
-	sg = hwif->sg_table;
 	while (i && sg_dma_len(sg)) {
 		dma_addr_t cur_addr;
 		int cur_len;

drivers/ide/tx4939ide.c

@@ -240,10 +240,6 @@ static int tx4939ide_build_dmatable(ide_drive_t *drive, struct request *rq)
 	int i;
 	struct scatterlist *sg;
 
-	hwif->sg_nents = ide_build_sglist(drive, rq);
-	if (hwif->sg_nents == 0)
-		return 0;
-
 	for_each_sg(hwif->sg_table, sg, hwif->sg_nents, i) {
 		u32 cur_addr, cur_len, bcount;
 

include/linux/ide.h

@@ -1477,6 +1477,8 @@ static inline int ide_set_dma(ide_drive_t *drive) { return 1; }
 static inline void ide_check_dma_crc(ide_drive_t *drive) { ; }
 static inline ide_startstop_t ide_dma_timeout_retry(ide_drive_t *drive, int error) { return ide_stopped; }
 static inline void ide_release_dma_engine(ide_hwif_t *hwif) { ; }
+static inline int ide_build_sglist(ide_drive_t *drive,
+				   struct request *rq) { return 0; }
 #endif /* CONFIG_BLK_DEV_IDEDMA */
 
 #ifdef CONFIG_BLK_DEV_IDEACPI