re:[PATCH] libata: add support for ATA_16 commands to ATAPI devices

[Mark Lord <liml@rtr.ca>]

On Tuesday 02 January 2007 19:39, Mark Lord wrote:
> This patch adds support for passing ATA_16 commands
> through to ATAPI devices in libata.  In practice, the upper layers will
> still currently prevent ATA_16 commands, as no (?) ATAPI drives support
> them yet.  But it will work if such a drive is ever encountered.

The above comment is out of date -- nuke it.
Instead, there is now a separate patch to permit ATA_16 commands
for 12-byte libata devices.

The rest of this stuff is still correct no changes below).

* * *
Support for ATA_16 is necessary for using SG_IO from userspace,
and an upcoming hdparm release will be updated to use this interface.

This version is very similar to the earlier first submission,
except that ATA_12 is no longer passed through to ATAPI
because of the conflict it has with the SCSI BLANK opcode.

Signed-off-by:  Mark Lord <mlord@pobox.com>

--- old/drivers/ata/libata-scsi.c	2007-01-02 19:20:23.000000000 -0500
+++ new/drivers/ata/libata-scsi.c	2007-01-02 19:20:49.000000000 -0500
@@ -2650,6 +2650,12 @@
 
 static inline ata_xlat_func_t ata_get_xlat_func(struct ata_device *dev, u8 cmd)
 {
+	if (cmd == ATA_16)
+		return ata_scsi_pass_thru;
+
+	if (dev->class == ATA_DEV_ATAPI)
+		return atapi_xlat;
+
 	switch (cmd) {
 	case READ_6:
 	case READ_10:
@@ -2670,7 +2676,6 @@
 		return ata_scsi_verify_xlat;
 
 	case ATA_12:
-	case ATA_16:
 		return ata_scsi_pass_thru;
 
 	case START_STOP:
@@ -2708,6 +2713,7 @@
 				      void (*done)(struct scsi_cmnd *),
 				      struct ata_device *dev)
 {
+	ata_xlat_func_t xlat_func;
 	int rc = 0;
 
 	if (unlikely(!scmd->cmd_len)) {
@@ -2717,17 +2723,11 @@
 		return 0;
 	}
 
-	if (dev->class == ATA_DEV_ATA) {
-		ata_xlat_func_t xlat_func = ata_get_xlat_func(dev,
-							      scmd->cmnd[0]);
-
-		if (xlat_func)
-			rc = ata_scsi_translate(dev, scmd, done, xlat_func);
-		else
-			ata_scsi_simulate(dev, scmd, done);
-	} else
-		rc = ata_scsi_translate(dev, scmd, done, atapi_xlat);
-
+	xlat_func = ata_get_xlat_func(dev, scmd->cmnd[0]);
+	if (xlat_func)
+		rc = ata_scsi_translate(dev, scmd, done, xlat_func);
+	else
+		ata_scsi_simulate(dev, scmd, done);
 	return rc;
 }