libata-core: Document some limits/assumptions about ID_ATA
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 75ccf46..d2141a0 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -1618,6 +1618,9 @@
* devices. This function also issues ATA_CMD_INIT_DEV_PARAMS
* for pre-ATA4 drives.
*
+ * FIXME: ATA_CMD_ID_ATA is optional for early drives and right
+ * now we abort if we hit that case.
+ *
* LOCKING:
* Kernel thread context (may sleep)
*
@@ -1745,10 +1748,13 @@
/*
* The exact sequence expected by certain pre-ATA4 drives is:
* SRST RESET
- * IDENTIFY
- * INITIALIZE DEVICE PARAMETERS
+ * IDENTIFY (optional in early ATA)
+ * INITIALIZE DEVICE PARAMETERS (later IDE and ATA)
* anything else..
* Some drives were very specific about that exact sequence.
+ *
+ * Note that ATA4 says lba is mandatory so the second check
+ * shoud never trigger.
*/
if (ata_id_major_version(id) < 4 || !ata_id_has_lba(id)) {
err_mask = ata_dev_init_params(dev, id[3], id[6]);
