libata-acpi: implement dev->gtf_cache and evaluate _GTF right after _STM during resume

On certain implementations, _GTF evaluation depends on preceding _STM
and both can be pretty picky about the configuration.  Using _GTM
result cached during controller initialization satisfies the most
neurotic _STM implementation.  However, libata evaluates _GTF after
reset during device configuration and the hardware state can be
different from what _GTF expects and can cause evaluation failure.

This patch adds dev->gtf_cache and updates ata_dev_get_GTF() such that
it uses the cached value if available.  Cache is cleared with a call
to ata_acpi_clear_gtf().

Because for SATA ACPI nodes _GTF must be evaluated after _SDD which
can't be done till IDENTIFY is complete, _GTF caching from
ata_acpi_on_resume() is used only for IDE ACPI nodes.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/libata.h b/include/linux/libata.h
index ba84d8a37545..cb91280be9bd 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -498,6 +498,7 @@ struct ata_device {
         struct scsi_device      *sdev;          /* attached SCSI device */
 #ifdef CONFIG_ATA_ACPI
         acpi_handle             acpi_handle;
+        union acpi_object       *gtf_cache;
 #endif
         /* n_sector is used as CLEAR_OFFSET, read comment above CLEAR_OFFSET */
         u64                     n_sectors;      /* size of device, if ATA */