ide: rework the code for selecting the best DMA transfer mode (v3)

Depends on the "ide: fix UDMA/MWDMA/SWDMA masks" patch.

* add ide_hwif_t.udma_filter hook for filtering UDMA mask
  (use it in alim15x3, hpt366, siimage and serverworks drivers)
* add ide_max_dma_mode() for finding best DMA mode for the device
  (loosely based on some older libata-core.c code)
* convert ide_dma_speed() users to use ide_max_dma_mode()
* make ide_rate_filter() take "ide_drive_t *drive" as an argument instead
  of "u8 mode" and teach it to how to use UDMA mask to do filtering
* use ide_rate_filter() in hpt366 driver
* remove no longer needed ide_dma_speed() and *_ratemask()
* unexport eighty_ninty_three()

v2:
* rename ->filter_udma_mask to ->udma_filter
  [ Suggested by Sergei Shtylyov <sshtylyov@ru.mvista.com>. ]

v3:
* updated for scc_pata driver (fixes XFER_UDMA_6 filtering for user-space
  originated transfer mode change requests when 100MHz clock is used)

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

1 files changed, 2 insertions, 18 deletions

diff --git a/drivers/ide/pci/it821x.c b/drivers/ide/pci/it821x.c
index 4e1254813ee0..442f658c6ae7 100644
--- a/drivers/ide/pci/it821x.c
+++ b/drivers/ide/pci/it821x.c
@@ -229,22 +229,6 @@ static void it821x_clock_strategy(ide_drive_t *drive)
 }
 
 /**
- *      it821x_ratemask -       Compute available modes
- *      @drive: IDE drive
- *
- *      Compute the available speeds for the devices on the interface. This
- *      is all modes to ATA133 clipped by drive cable setup.
- */
-
-static u8 it821x_ratemask (ide_drive_t *drive)
-{
-        u8 mode = 4;
-        if (!eighty_ninty_three(drive))
-                mode = min(mode, (u8)1);
-        return mode;
-}
-
-/**
  *      it821x_tunepio  -       tune a drive
  *      @drive: drive to tune
  *      @pio: the desired PIO mode
@@ -438,7 +422,7 @@ static int it821x_tune_chipset (ide_drive_t *drive, byte xferspeed)
 
         ide_hwif_t *hwif        = drive->hwif;
         struct it821x_dev *itdev = ide_get_hwifdata(hwif);
-        u8 speed                = ide_rate_filter(it821x_ratemask(drive), xferspeed);
+        u8 speed                = ide_rate_filter(drive, xferspeed);
 
         switch (speed) {
         case XFER_PIO_4:
@@ -488,7 +472,7 @@ static int it821x_tune_chipset (ide_drive_t *drive, byte xferspeed)
 
 static int config_chipset_for_dma (ide_drive_t *drive)
 {
-        u8 speed        = ide_dma_speed(drive, it821x_ratemask(drive));
+        u8 speed = ide_max_dma_mode(drive);
 
         if (speed == 0)
                 return 0;