ide: add IDE_HFLAG_ABUSE_SET_DMA_MODE host flag

* Add IDE_HFLAG_ABUSE_SET_DMA_MODE host flag and use it to decide
  what to do with transfer modes < XFER_PIO_0 in ide_set_xfer_rate().

* Set IDE_HFLAG_ABUSE_SET_DMA_MODE in host drivers that need it
  (aec62xx, amd74xx, cs5520, cs5535, hpt34x, hpt366, pdc202xx_old,
  serverworks, tc86c001 and via82cxxx) and cleanup ->set_dma_mode
  methods in host drivers that don't (IDE core code guarantees that
  ->set_dma_mode will be called only for modes which are present
  in SWDMA/MWDMA/UDMA masks).

While at it:

* Add IDE_HFLAGS_HPT34X/HPT3XX/PDC202XX/SVWKS define in
  hpt34x/hpt366/pdc202xx_old/serverworks host driver.

There should be no functionality changes caused by this patch.

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

1 files changed, 4 insertions, 13 deletions

diff --git a/drivers/ide/pci/piix.c b/drivers/ide/pci/piix.c
index 27781d294cea..bd6d3f77d30c 100644
--- a/drivers/ide/pci/piix.c
+++ b/drivers/ide/pci/piix.c
@@ -203,20 +203,11 @@ static void piix_set_dma_mode(ide_drive_t *drive, const u8 speed)
         pci_read_config_byte(dev, 0x54, &reg54);
         pci_read_config_byte(dev, 0x55, &reg55);
 
-        switch(speed) {
-                case XFER_UDMA_4:
-                case XFER_UDMA_2:       u_speed = 2 << (drive->dn * 4); break;
-                case XFER_UDMA_5:
-                case XFER_UDMA_3:
-                case XFER_UDMA_1:       u_speed = 1 << (drive->dn * 4); break;
-                case XFER_UDMA_0:       u_speed = 0 << (drive->dn * 4); break;
-                case XFER_MW_DMA_2:
-                case XFER_MW_DMA_1:
-                case XFER_SW_DMA_2:     break;
-                default:                return;
-        }
-
         if (speed >= XFER_UDMA_0) {
+                u8 udma = speed - XFER_UDMA_0;
+
+                u_speed = min_t(u8, 2 - (udma & 1), udma) << (drive->dn * 4);
+
                 if (!(reg48 & u_flag))
                         pci_write_config_byte(dev, 0x48, reg48 | u_flag);
                 if (speed == XFER_UDMA_5) {