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, 14 insertions, 51 deletions

diff --git a/drivers/ide/pci/cmd64x.c b/drivers/ide/pci/cmd64x.c
index 610c45f7b4e2..19f5ac1f866c 100644
--- a/drivers/ide/pci/cmd64x.c
+++ b/drivers/ide/pci/cmd64x.c
@@ -292,55 +292,6 @@ static void cmd64x_tune_drive (ide_drive_t *drive, u8 pio)
         (void) ide_config_drive_speed(drive, XFER_PIO_0 + pio);
 }
 
-static u8 cmd64x_ratemask (ide_drive_t *drive)
-{
-        struct pci_dev *dev     = HWIF(drive)->pci_dev;
-        u8 mode = 0;
-
-        switch(dev->device) {
-                case PCI_DEVICE_ID_CMD_649:
-                        mode = 3;
-                        break;
-                case PCI_DEVICE_ID_CMD_648:
-                        mode = 2;
-                        break;
-                case PCI_DEVICE_ID_CMD_643:
-                        return 0;
-
-                case PCI_DEVICE_ID_CMD_646:
-                {
-                        unsigned int class_rev  = 0;
-                        pci_read_config_dword(dev,
-                                PCI_CLASS_REVISION, &class_rev);
-                        class_rev &= 0xff;
-                /*
-                 * UltraDMA only supported on PCI646U and PCI646U2, which
-                 * correspond to revisions 0x03, 0x05 and 0x07 respectively.
-                 * Actually, although the CMD tech support people won't
-                 * tell me the details, the 0x03 revision cannot support
-                 * UDMA correctly without hardware modifications, and even
-                 * then it only works with Quantum disks due to some
-                 * hold time assumptions in the 646U part which are fixed
-                 * in the 646U2.
-                 *
-                 * So we only do UltraDMA on revision 0x05 and 0x07 chipsets.
-                 */
-                        switch(class_rev) {
-                                case 0x07:
-                                case 0x05:
-                                        return 1;
-                                case 0x03:
-                                case 0x01:
-                                default:
-                                        return 0;
-                        }
-                }
-        }
-        if (!eighty_ninty_three(drive))
-                mode = min(mode, (u8)1);
-        return mode;
-}
-
 static int cmd64x_tune_chipset (ide_drive_t *drive, u8 speed)
 {
         ide_hwif_t *hwif        = HWIF(drive);
@@ -348,7 +299,7 @@ static int cmd64x_tune_chipset (ide_drive_t *drive, u8 speed)
         u8 unit                 = drive->dn & 0x01;
         u8 regU = 0, pciU       = hwif->channel ? UDIDETCR1 : UDIDETCR0;
 
-        speed = ide_rate_filter(cmd64x_ratemask(drive), speed);
+        speed = ide_rate_filter(drive, speed);
 
         if (speed >= XFER_SW_DMA_0) {
                 (void) pci_read_config_byte(dev, pciU, &regU);
@@ -403,7 +354,7 @@ static int cmd64x_tune_chipset (ide_drive_t *drive, u8 speed)
 
 static int config_chipset_for_dma (ide_drive_t *drive)
 {
-        u8 speed        = ide_dma_speed(drive, cmd64x_ratemask(drive));
+        u8 speed = ide_max_dma_mode(drive);
 
         if (!speed)
                 return 0;
@@ -646,6 +597,18 @@ static void __devinit init_hwif_cmd64x(ide_hwif_t *hwif)
 
         hwif->ultra_mask = hwif->cds->udma_mask;
 
+        /*
+         * UltraDMA only supported on PCI646U and PCI646U2, which
+         * correspond to revisions 0x03, 0x05 and 0x07 respectively.
+         * Actually, although the CMD tech support people won't
+         * tell me the details, the 0x03 revision cannot support
+         * UDMA correctly without hardware modifications, and even
+         * then it only works with Quantum disks due to some
+         * hold time assumptions in the 646U part which are fixed
+         * in the 646U2.
+         *
+         * So we only do UltraDMA on revision 0x05 and 0x07 chipsets.
+         */
         if (dev->device == PCI_DEVICE_ID_CMD_646 && class_rev < 5)
                 hwif->ultra_mask = 0x00;