From: Hannes Reinecke ICH6 spec defines the PORT_ bits as: PORT_ENABLED (R/W): 0 = Disabled. The port is in the off state and cannot detect any devices. 1 = Enabled. The port can transition between the on, partial, and slumber states and can detect devices. PORT_PRESENT (R/O) The status of this bit may change at any time. This bit is cleared when the port is disabled via PORT_ENABLED. This bit is not cleared upon surprise removal of a device. So from a textual view it is not necessary that PORT_PRESENT _must_ be set, especially if a device detection has to be done anyway. And, in fact, this is the view that ACER has been taken with its new Laptops (e.g. Travelmate 4150). And the definition of PORT_ENABLED / PORT_PRESENT is mixed up, btw. Signed-off-by: Hannes Reinecke Signed-off-by: Jens Axboe Cc: Jeff Garzik Signed-off-by: Andrew Morton --- drivers/scsi/ata_piix.c | 10 ++++++---- 1 files changed, 6 insertions(+), 4 deletions(-) diff -puN drivers/scsi/ata_piix.c~scan-all-enabled-ports-on-ata_piix drivers/scsi/ata_piix.c --- 25/drivers/scsi/ata_piix.c~scan-all-enabled-ports-on-ata_piix 2005-05-31 02:44:18.000000000 -0700 +++ 25-akpm/drivers/scsi/ata_piix.c 2005-05-31 02:44:18.000000000 -0700 @@ -49,8 +49,8 @@ enum { PIIX_COMB_PATA_P0 = (1 << 1), PIIX_COMB = (1 << 2), /* combined mode enabled? */ - PIIX_PORT_PRESENT = (1 << 0), - PIIX_PORT_ENABLED = (1 << 4), + PIIX_PORT_ENABLED = (1 << 0), + PIIX_PORT_PRESENT = (1 << 4), PIIX_80C_PRI = (1 << 5) | (1 << 4), PIIX_80C_SEC = (1 << 7) | (1 << 6), @@ -356,7 +356,9 @@ static void piix_pata_phy_reset(struct a * None (inherited from caller). * * RETURNS: - * Non-zero if device detected, zero otherwise. + * Non-zero if port is enabled, it may or may not have a device + * attached in that case (PRESENT bit would only be set if BIOS probe + * was done). Zero is returned if port is disabled. */ static int piix_sata_probe (struct ata_port *ap) { @@ -380,7 +382,7 @@ static int piix_sata_probe (struct ata_p */ for (i = 0; i < 4; i++) { - mask = (PIIX_PORT_PRESENT << i) | (PIIX_PORT_ENABLED << i); + mask = (PIIX_PORT_ENABLED << i); if ((orig_mask & mask) == mask) if (combined || (i == ap->hard_port_no)) _