libata: make SFF support optional

Now that SFF support is completely separated out from the core layer,
it can be made optional.  Add CONFIG_ATA_SFF and let SFF drivers
depend on it.  If CONFIG_ATA_SFF isn't set, all codes in libata-sff.c
and data structures for SFF support are disabled.  This saves good
number of bytes for small systems.

Signed-off-by: Tejun Heo <htejun@gmail.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 3a94c69c7fe7..ca60af0cb051 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -5195,7 +5195,9 @@ struct ata_port *ata_port_alloc(struct ata_host *host)
         ap->msg_enable = ATA_MSG_DRV | ATA_MSG_ERR | ATA_MSG_WARN;
 #endif
 
+#ifdef CONFIG_ATA_SFF
         INIT_DELAYED_WORK(&ap->port_task, ata_pio_task);
+#endif
         INIT_DELAYED_WORK(&ap->hotplug_task, ata_scsi_hotplug);
         INIT_WORK(&ap->scsi_rescan_task, ata_scsi_dev_rescan);
         INIT_LIST_HEAD(&ap->eh_done_q);