[PATCH 16/20] libata-acpi: allow _GTF on SATA, but disable on PATA for now

[Len Brown <len.brown@intel.com>]

From: Kristen Accardi <kristen.c.accardi@intel.com>

The ACPI specification states, and BIOS implementations depend on,
_STM being called before _GTF.

SATA does this, but PATA does not.  So for now, simply
prevent execution of _GTF on PATA devices.  Longer term we
should implement ACPI support for PATA devices in libata.

Signed-off-by: Kristen Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
---
 drivers/ata/libata-acpi.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/drivers/ata/libata-acpi.c b/drivers/ata/libata-acpi.c
index d14a48e..89aaf74 100644
--- a/drivers/ata/libata-acpi.c
+++ b/drivers/ata/libata-acpi.c
@@ -561,6 +561,13 @@ int ata_acpi_exec_tfs(struct ata_port *ap)
 
 	if (noacpi)
 		return 0;
+	/*
+	 * TBD - implement PATA support.  For now,
+	 * we should not run GTF on PATA devices since some
+	 * PATA require execution of GTM/STM before GTF.
+	 */
+	if (!(ap->cbl == ATA_CBL_SATA))
+		return 0;
 
 	for (ix = 0; ix < ATA_MAX_DEVICES; ix++) {
 		if (!ata_dev_enabled(&ap->device[ix]))
-- 
1.5.0.3.310.g05ef5