[PATCH] libata-ncq: implement NCQ device configuration

Now that all NCQ related stuff are in place, implement NCQ device
configuration and bump ATA_MAX_QUEUE to 32 thus activating NCQ
support.

Original implementation is from Jens Axboe.

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

drivers/scsi/libata-core.c

@@ -1251,6 +1251,28 @@ static inline u8 ata_dev_knobble(struct ata_device *dev)
 	return ((dev->ap->cbl == ATA_CBL_SATA) && (!ata_id_is_sata(dev->id)));
 }
 
+static void ata_dev_config_ncq(struct ata_device *dev,
+			       char *desc, size_t desc_sz)
+{
+	struct ata_port *ap = dev->ap;
+	int hdepth = 0, ddepth = ata_id_queue_depth(dev->id);
+
+	if (!ata_id_has_ncq(dev->id)) {
+		desc[0] = '\0';
+		return;
+	}
+
+	if (ap->flags & ATA_FLAG_NCQ) {
+		hdepth = min(ap->host->can_queue, ATA_MAX_QUEUE - 1);
+		dev->flags |= ATA_DFLAG_NCQ;
+	}
+
+	if (hdepth >= ddepth)
+		snprintf(desc, desc_sz, "NCQ (depth %d)", ddepth);
+	else
+		snprintf(desc, desc_sz, "NCQ (depth %d/%d)", hdepth, ddepth);
+}
+
 /**
  *	ata_dev_configure - Configure the specified ATA/ATAPI device
  *	@dev: Target device to configure
@@ -1311,6 +1333,7 @@ static int ata_dev_configure(struct ata_device *dev, int print_info)
 
 		if (ata_id_has_lba(id)) {
 			const char *lba_desc;
+			char ncq_desc[20];
 
 			lba_desc = "LBA";
 			dev->flags |= ATA_DFLAG_LBA;
@@ -1319,14 +1342,17 @@ static int ata_dev_configure(struct ata_device *dev, int print_info)
 				lba_desc = "LBA48";
 			}
 
+			/* config NCQ */
+			ata_dev_config_ncq(dev, ncq_desc, sizeof(ncq_desc));
+
 			/* print device info to dmesg */
 			if (print_info)
 				ata_dev_printk(dev, KERN_INFO, "ATA-%d, "
-					"max %s, %Lu sectors: %s\n",
+					"max %s, %Lu sectors: %s %s\n",
 					ata_id_major_version(id),
 					ata_mode_string(xfer_mask),
 					(unsigned long long)dev->n_sectors,
-					lba_desc);
+					lba_desc, ncq_desc);
 		} else {
 			/* CHS */
 
@@ -5675,6 +5701,7 @@ EXPORT_SYMBOL_GPL(ata_port_queue_task);
 EXPORT_SYMBOL_GPL(ata_scsi_ioctl);
 EXPORT_SYMBOL_GPL(ata_scsi_queuecmd);
 EXPORT_SYMBOL_GPL(ata_scsi_slave_config);
+EXPORT_SYMBOL_GPL(ata_scsi_change_queue_depth);
 EXPORT_SYMBOL_GPL(ata_scsi_release);
 EXPORT_SYMBOL_GPL(ata_host_intr);
 EXPORT_SYMBOL_GPL(sata_scr_valid);

drivers/scsi/libata-scsi.c

@@ -41,6 +41,7 @@
 #include <scsi/scsi_eh.h>
 #include <scsi/scsi_device.h>
 #include <scsi/scsi_request.h>
+#include <scsi/scsi_tcq.h>
 #include <scsi/scsi_transport.h>
 #include <linux/libata.h>
 #include <linux/hdreg.h>
@@ -684,6 +685,14 @@ static void ata_scsi_dev_config(struct scsi_device *sdev,
 		request_queue_t *q = sdev->request_queue;
 		blk_queue_max_hw_segments(q, q->max_hw_segments - 1);
 	}
+
+	if (dev->flags & ATA_DFLAG_NCQ) {
+		int depth;
+
+		depth = min(sdev->host->can_queue, ata_id_queue_depth(dev->id));
+		depth = min(ATA_MAX_QUEUE - 1, depth);
+		scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, depth);
+	}
 }
 
 /**
@@ -717,6 +726,43 @@ int ata_scsi_slave_config(struct scsi_device *sdev)
 	return 0;	/* scsi layer doesn't check return value, sigh */
 }
 
+/**
+ *	ata_scsi_change_queue_depth - SCSI callback for queue depth config
+ *	@sdev: SCSI device to configure queue depth for
+ *	@queue_depth: new queue depth
+ *
+ *	This is libata standard hostt->change_queue_depth callback.
+ *	SCSI will call into this callback when user tries to set queue
+ *	depth via sysfs.
+ *
+ *	LOCKING:
+ *	SCSI layer (we don't care)
+ *
+ *	RETURNS:
+ *	Newly configured queue depth.
+ */
+int ata_scsi_change_queue_depth(struct scsi_device *sdev, int queue_depth)
+{
+	struct ata_port *ap = ata_shost_to_port(sdev->host);
+	struct ata_device *dev;
+	int max_depth;
+
+	if (queue_depth < 1)
+		return sdev->queue_depth;
+
+	dev = ata_scsi_find_dev(ap, sdev);
+	if (!dev || !ata_dev_enabled(dev))
+		return sdev->queue_depth;
+
+	max_depth = min(sdev->host->can_queue, ata_id_queue_depth(dev->id));
+	max_depth = min(ATA_MAX_QUEUE - 1, max_depth);
+	if (queue_depth > max_depth)
+		queue_depth = max_depth;
+
+	scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, queue_depth);
+	return queue_depth;
+}
+
 /**
  *	ata_scsi_start_stop_xlat - Translate SCSI START STOP UNIT command
  *	@qc: Storage for translated ATA taskfile

include/linux/libata.h

@@ -109,7 +109,7 @@ enum {
 	ATA_MAX_PORTS		= 8,
 	ATA_DEF_QUEUE		= 1,
 	/* tag ATA_MAX_QUEUE - 1 is reserved for internal commands */
-	ATA_MAX_QUEUE		= 2,
+	ATA_MAX_QUEUE		= 32,
 	ATA_TAG_INTERNAL	= ATA_MAX_QUEUE - 1,
 	ATA_MAX_SECTORS		= 200,	/* FIXME */
 	ATA_MAX_BUS		= 2,
@@ -679,6 +679,8 @@ extern int ata_std_bios_param(struct scsi_device *sdev,
 			      struct block_device *bdev,
 			      sector_t capacity, int geom[]);
 extern int ata_scsi_slave_config(struct scsi_device *sdev);
+extern int ata_scsi_change_queue_depth(struct scsi_device *sdev,
+				       int queue_depth);
 extern struct ata_device *ata_dev_pair(struct ata_device *adev);
 
 /*