libata: implement dump_id force param

Add dump_id libata.force parameter.  If specified, libata dumps full
IDENTIFY data during device configuration.  This is to aid debugging.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Larry Baker <baker@usgs.gov>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 8959f42..06b7e49 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -2126,6 +2126,14 @@
 		goto err_out;
 	}
 
+	if (dev->horkage & ATA_HORKAGE_DUMP_ID) {
+		ata_dev_printk(dev, KERN_DEBUG, "dumping IDENTIFY data, "
+			       "class=%d may_fallback=%d tried_spinup=%d\n",
+			       class, may_fallback, tried_spinup);
+		print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET,
+			       16, 2, id, ATA_ID_WORDS * sizeof(*id), true);
+	}
+
 	/* Falling back doesn't make sense if ID data was read
 	 * successfully at least once.
 	 */
@@ -6377,6 +6385,7 @@
 		{ "3.0Gbps",	.spd_limit	= 2 },
 		{ "noncq",	.horkage_on	= ATA_HORKAGE_NONCQ },
 		{ "ncq",	.horkage_off	= ATA_HORKAGE_NONCQ },
+		{ "dump_id",	.horkage_on	= ATA_HORKAGE_DUMP_ID },
 		{ "pio0",	.xfer_mask	= 1 << (ATA_SHIFT_PIO + 0) },
 		{ "pio1",	.xfer_mask	= 1 << (ATA_SHIFT_PIO + 1) },
 		{ "pio2",	.xfer_mask	= 1 << (ATA_SHIFT_PIO + 2) },