libata: fix ata_acpi_gtm_xfermask()

ata_acpi_gtm_xfermask() as separated out from pacpi_discover_modes()
has various bugs.  Fix them.

* The wrong comparison operator is used when finding for matching
  cycle resulting totally bogus result.

* With the comparion operator fixed, boundary condtion handling is
  clumsy.

* Setting of any DMA mask bit set all bits in PIO mask.

* MWDMA and UDMA blocks are swapped.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

diff --git a/drivers/ata/libata-acpi.c b/drivers/ata/libata-acpi.c
index d6697baf243d3227b9dc442e6ff6d13390fcccb7..9f0b208afcf5102d51a47db2eca5d774d9c398b3 100644 (file)
--- a/drivers/ata/libata-acpi.c
+++ b/drivers/ata/libata-acpi.c
@@ -473,49 +473,49 @@ EXPORT_SYMBOL_GPL(ata_acpi_udma_cycle);
 unsigned long ata_acpi_gtm_xfermask(struct ata_device *dev,
                                    const struct ata_acpi_gtm *gtm)
 {
+       unsigned long pio_mask = 0, mwdma_mask = 0, udma_mask = 0;
        int unit, i;
        u32 t;
-       unsigned long mask = (0x7f << ATA_SHIFT_UDMA) | (0x7 << ATA_SHIFT_MWDMA) | (0x1F << ATA_SHIFT_PIO);
 
        /* we always use the 0 slot for crap hardware */
        unit = dev->devno;
        if (!(gtm->flags & 0x10))
                unit = 0;
 
+       /* Values larger than the longest cycle results in 0 mask
+        * while values equal to smaller than the shortest cycle
+        * results in mask which includes all supported modes.
+        * Disabled transfer method has the value of 0xffffffff which
+        * will always result in 0 mask.
+        */
+
        /* start by scanning for PIO modes */
-       for (i = 0; i < 7; i++) {
-               t = gtm->drive[unit].pio;
-               if (t <= ata_acpi_pio_cycle[i]) {
-                       mask |= (2 << (ATA_SHIFT_PIO + i)) - 1;
+       t = gtm->drive[unit].pio;
+       for (i = 0; i < ARRAY_SIZE(ata_acpi_pio_cycle); i++)
+               if (t > ata_acpi_pio_cycle[i])
                        break;
-               }
-       }
+       pio_mask = (1 << i) - 1;
 
        /* See if we have MWDMA or UDMA data. We don't bother with
         * MWDMA if UDMA is available as this means the BIOS set UDMA
         * and our error changedown if it works is UDMA to PIO anyway.
         */
-       if (gtm->flags & (1 << (2 * unit))) {
+       t = gtm->drive[unit].dma;
+       if (!(gtm->flags & (1 << (2 * unit)))) {
                /* MWDMA */
-               for (i = 0; i < 5; i++) {
-                       t = gtm->drive[unit].dma;
-                       if (t <= ata_acpi_mwdma_cycle[i]) {
-                               mask |= (2 << (ATA_SHIFT_MWDMA + i)) - 1;
+               for (i = 0; i < ARRAY_SIZE(ata_acpi_mwdma_cycle); i++)
+                       if (t > ata_acpi_mwdma_cycle[i])
                                break;
-                       }
-               }
+               mwdma_mask = (1 << i) - 1;
        } else {
                /* UDMA */
-               for (i = 0; i < 7; i++) {
-                       t = gtm->drive[unit].dma;
-                       if (t <= ata_acpi_udma_cycle[i]) {
-                               mask |= (2 << (ATA_SHIFT_UDMA + i)) - 1;
+               for (i = 0; i < ARRAY_SIZE(ata_acpi_udma_cycle); i++)
+                       if (t > ata_acpi_udma_cycle[i])
                                break;
-                       }
-               }
+               udma_mask = (1 << i) - 1;
        }
 
-       return mask;
+       return ata_pack_xfermask(pio_mask, mwdma_mask, udma_mask);
 }
 EXPORT_SYMBOL_GPL(ata_acpi_gtm_xfermask);