atiixp/jmicron/triflex: fix PIO fallback

* atiixp: if DMA can't be used atiixp_config_drive_for_dma() should return 0,
  atiixp_dma_check() will tune the correct PIO mode anyway

* jmicron: if DMA can't be used config_chipset_for_dma() should return 0,
  micron_config_drive_for_dma() will tune the correct PIO mode anyway

  config_jmicron_chipset_for_pio(drive, !speed) doesn't program
  device transfer mode for speed != 0 (only wastes some CPU cycles
  on ide_get_best_pio_mode() call) so remove it

* triflex: if DMA can't be used triflex_config_drive_for_dma() should return 0,
  triflex_config_drive_xfer_rate() will tune correct PIO mode anyway

Above changes also fix (theoretical) issue when ->speedproc fails to set
device transfer mode (i.e. when ide_config_drive_speed() fails to program it)
but one of DMA transfer modes is already enabled on the device by the BIOS.
In such scenario ide_dma_enable() will incorrectly return true statement
and ->ide_dma_check will try to enable DMA on the device.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

1 files changed, 2 insertions, 5 deletions

diff --git a/drivers/ide/pci/atiixp.c b/drivers/ide/pci/atiixp.c
index 982ac31fa99..922b315da4a 100644
--- a/drivers/ide/pci/atiixp.c
+++ b/drivers/ide/pci/atiixp.c
@@ -235,11 +235,8 @@ static int atiixp_config_drive_for_dma(ide_drive_t *drive)
 {
 	u8 speed = ide_dma_speed(drive, atiixp_ratemask(drive));
 
-	/* If no DMA speed was available then disable DMA and use PIO. */
-	if (!speed) {
-		u8 tspeed = ide_get_best_pio_mode(drive, 255, 5, NULL);
-		speed = atiixp_dma_2_pio(XFER_PIO_0 + tspeed) + XFER_PIO_0;
-	}
+	if (!speed)
+		return 0;
 
 	(void) atiixp_speedproc(drive, speed);
 	return ide_dma_enable(drive);