[PATCH] libata: Pre UDMA EIDE PIO mode selection

I misread the spec when doing the original. I've tested the corrected
version with pre UDMA drives and it now picks the right modes. This is a
specific bug fix rather than an update or new feature item.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

1 files changed, 9 insertions, 5 deletions

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 99bae8369ab2..bc48d88fef5a 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -1051,18 +1051,22 @@ static unsigned int ata_pio_modes(const struct ata_device *adev)
 {
         u16 modes;
 
-        /* Usual case. Word 53 indicates word 88 is valid */
-        if (adev->id[ATA_ID_FIELD_VALID] & (1 << 2)) {
+        /* Usual case. Word 53 indicates word 64 is valid */
+        if (adev->id[ATA_ID_FIELD_VALID] & (1 << 1)) {
                 modes = adev->id[ATA_ID_PIO_MODES] & 0x03;
                 modes <<= 3;
                 modes |= 0x7;
                 return modes;
         }
 
-        /* If word 88 isn't valid then Word 51 holds the PIO timing number
-           for the maximum. Turn it into a mask and return it */
-        modes = (2 << (adev->id[ATA_ID_OLD_PIO_MODES] & 0xFF)) - 1 ;
+        /* If word 64 isn't valid then Word 51 high byte holds the PIO timing
+           number for the maximum. Turn it into a mask and return it */
+        modes = (2 << ((adev->id[ATA_ID_OLD_PIO_MODES] >> 8) & 0xFF)) - 1 ;
         return modes;
+        /* But wait.. there's more. Design your standards by committee and
+           you too can get a free iordy field to process. However its the 
+           speeds not the modes that are supported... Note drivers using the
+           timing API will get this right anyway */
 }
 
 struct ata_exec_internal_arg {