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-rw-r--r--drivers/ide/ide-lib.c125
1 files changed, 73 insertions, 52 deletions
diff --git a/drivers/ide/ide-lib.c b/drivers/ide/ide-lib.c
index 850ef63cc98..8237d89eec6 100644
--- a/drivers/ide/ide-lib.c
+++ b/drivers/ide/ide-lib.c
@@ -71,75 +71,96 @@ EXPORT_SYMBOL(ide_xfer_verbose);
/**
* ide_dma_speed - compute DMA speed
* @drive: drive
- * @mode; intended mode
+ * @mode: modes available
*
* Checks the drive capabilities and returns the speed to use
- * for the transfer. Returns -1 if the requested mode is unknown
- * (eg PIO)
+ * for the DMA transfer. Returns 0 if the drive is incapable
+ * of DMA transfers.
*/
u8 ide_dma_speed(ide_drive_t *drive, u8 mode)
{
struct hd_driveid *id = drive->id;
ide_hwif_t *hwif = HWIF(drive);
+ u8 ultra_mask, mwdma_mask, swdma_mask;
u8 speed = 0;
if (drive->media != ide_disk && hwif->atapi_dma == 0)
return 0;
- switch(mode) {
- case 0x04:
- if ((id->dma_ultra & 0x0040) &&
- (id->dma_ultra & hwif->ultra_mask))
- { speed = XFER_UDMA_6; break; }
- case 0x03:
- if ((id->dma_ultra & 0x0020) &&
- (id->dma_ultra & hwif->ultra_mask))
- { speed = XFER_UDMA_5; break; }
- case 0x02:
- if ((id->dma_ultra & 0x0010) &&
- (id->dma_ultra & hwif->ultra_mask))
- { speed = XFER_UDMA_4; break; }
- if ((id->dma_ultra & 0x0008) &&
- (id->dma_ultra & hwif->ultra_mask))
- { speed = XFER_UDMA_3; break; }
- case 0x01:
- if ((id->dma_ultra & 0x0004) &&
- (id->dma_ultra & hwif->ultra_mask))
- { speed = XFER_UDMA_2; break; }
- if ((id->dma_ultra & 0x0002) &&
- (id->dma_ultra & hwif->ultra_mask))
- { speed = XFER_UDMA_1; break; }
- if ((id->dma_ultra & 0x0001) &&
- (id->dma_ultra & hwif->ultra_mask))
- { speed = XFER_UDMA_0; break; }
- case 0x00:
- if ((id->dma_mword & 0x0004) &&
- (id->dma_mword & hwif->mwdma_mask))
- { speed = XFER_MW_DMA_2; break; }
- if ((id->dma_mword & 0x0002) &&
- (id->dma_mword & hwif->mwdma_mask))
- { speed = XFER_MW_DMA_1; break; }
- if ((id->dma_mword & 0x0001) &&
- (id->dma_mword & hwif->mwdma_mask))
- { speed = XFER_MW_DMA_0; break; }
- if ((id->dma_1word & 0x0004) &&
- (id->dma_1word & hwif->swdma_mask))
- { speed = XFER_SW_DMA_2; break; }
- if ((id->dma_1word & 0x0002) &&
- (id->dma_1word & hwif->swdma_mask))
- { speed = XFER_SW_DMA_1; break; }
- if ((id->dma_1word & 0x0001) &&
- (id->dma_1word & hwif->swdma_mask))
- { speed = XFER_SW_DMA_0; break; }
- }
+ /* Capable of UltraDMA modes? */
+ ultra_mask = id->dma_ultra & hwif->ultra_mask;
+
+ if (!(id->field_valid & 4))
+ mode = 0; /* fallback to MW/SW DMA if no UltraDMA */
+
+ switch (mode) {
+ case 4:
+ if (ultra_mask & 0x40) {
+ speed = XFER_UDMA_6;
+ break;
+ }
+ case 3:
+ if (ultra_mask & 0x20) {
+ speed = XFER_UDMA_5;
+ break;
+ }
+ case 2:
+ if (ultra_mask & 0x10) {
+ speed = XFER_UDMA_4;
+ break;
+ }
+ if (ultra_mask & 0x08) {
+ speed = XFER_UDMA_3;
+ break;
+ }
+ case 1:
+ if (ultra_mask & 0x04) {
+ speed = XFER_UDMA_2;
+ break;
+ }
+ if (ultra_mask & 0x02) {
+ speed = XFER_UDMA_1;
+ break;
+ }
+ if (ultra_mask & 0x01) {
+ speed = XFER_UDMA_0;
+ break;
+ }
+ case 0:
+ mwdma_mask = id->dma_mword & hwif->mwdma_mask;
-// printk("%s: %s: mode 0x%02x, speed 0x%02x\n",
-// __FUNCTION__, drive->name, mode, speed);
+ if (mwdma_mask & 0x04) {
+ speed = XFER_MW_DMA_2;
+ break;
+ }
+ if (mwdma_mask & 0x02) {
+ speed = XFER_MW_DMA_1;
+ break;
+ }
+ if (mwdma_mask & 0x01) {
+ speed = XFER_MW_DMA_0;
+ break;
+ }
+
+ swdma_mask = id->dma_1word & hwif->swdma_mask;
+
+ if (swdma_mask & 0x04) {
+ speed = XFER_SW_DMA_2;
+ break;
+ }
+ if (swdma_mask & 0x02) {
+ speed = XFER_SW_DMA_1;
+ break;
+ }
+ if (swdma_mask & 0x01) {
+ speed = XFER_SW_DMA_0;
+ break;
+ }
+ }
return speed;
}
-
EXPORT_SYMBOL(ide_dma_speed);