Subject: Re: [PATCH 15/16 v3] [v2] ibmvscsi: driver enablement for CMO

From: Robert Jennings <[email-masked]>
Date: Tue, 8 Jul 2008 15:35:54 -0500

From: Robert Jennings <[email-masked]>

I removed references to 'entitlement' after having changed the function
'get_io_entitlement' to 'get_desired_dma' to correctly indicate what the
function was doing.  Also, this function does not need to page align the
return value, the VIO bus is responsible for this.

(We would like to take this patch through linuxppc-dev with the full
change set for this feature.  We are copying linux-scsi for review and ack)

Enable the driver to function in a Cooperative Memory Overcommitment (CMO)
environment.

The following changes are made to enable the driver for CMO:
 * DMA mapping errors will not result in error messages if entitlement has
   been exceeded and resources were not available.
 * The driver has a get_desired_dma function defined to function
   in a CMO environment. It will indicate how much IO memory it would like
   to function.

Signed-off-by: Robert Jennings <[email-masked]>

---
 drivers/scsi/ibmvscsi/ibmvscsi.c |   45 +++++++++++++++++++++++++++++++++------
 drivers/scsi/ibmvscsi/ibmvscsi.h |    2 ++
 2 files changed, 40 insertions(+), 7 deletions(-)

Index: b/drivers/scsi/ibmvscsi/ibmvscsi.c
===================================================================
--- a/drivers/scsi/ibmvscsi/ibmvscsi.c
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
@@ -72,6 +72,7 @@
 #include <linux/delay.h>
 #include <asm/firmware.h>
 #include <asm/vio.h>
+#include <asm/firmware.h>
 #include <scsi/scsi.h>
 #include <scsi/scsi_cmnd.h>
 #include <scsi/scsi_host.h>
@@ -426,8 +427,10 @@ static int map_sg_data(struct scsi_cmnd 
 					   SG_ALL * sizeof(struct srp_direct_buf),
 					   &evt_struct->ext_list_token, 0);
 		if (!evt_struct->ext_list) {
-			sdev_printk(KERN_ERR, cmd->device,
-				    "Can't allocate memory for indirect table\n");
+			if (!firmware_has_feature(FW_FEATURE_CMO))
+				sdev_printk(KERN_ERR, cmd->device,
+				            "Can't allocate memory "
+				            "for indirect table\n");
 			return 0;
 		}
 	}
@@ -743,7 +746,9 @@ static int ibmvscsi_queuecommand(struct 
 	srp_cmd->lun = ((u64) lun) << 48;
 
 	if (!map_data_for_srp_cmd(cmnd, evt_struct, srp_cmd, hostdata->dev)) {
-		sdev_printk(KERN_ERR, cmnd->device, "couldn't convert cmd to srp_cmd\n");
+		if (!firmware_has_feature(FW_FEATURE_CMO))
+			sdev_printk(KERN_ERR, cmnd->device,
+			            "couldn't convert cmd to srp_cmd\n");
 		free_event_struct(&hostdata->pool, evt_struct);
 		return SCSI_MLQUEUE_HOST_BUSY;
 	}
@@ -855,7 +860,10 @@ static void send_mad_adapter_info(struct
 					    DMA_BIDIRECTIONAL);
 
 	if (dma_mapping_error(req->buffer)) {
-		dev_err(hostdata->dev, "Unable to map request_buffer for adapter_info!\n");
+		if (!firmware_has_feature(FW_FEATURE_CMO))
+			dev_err(hostdata->dev,
+			        "Unable to map request_buffer for "
+			        "adapter_info!\n");
 		free_event_struct(&hostdata->pool, evt_struct);
 		return;
 	}
@@ -1400,7 +1408,9 @@ static int ibmvscsi_do_host_config(struc
 						    DMA_BIDIRECTIONAL);
 
 	if (dma_mapping_error(host_config->buffer)) {
-		dev_err(hostdata->dev, "dma_mapping error getting host config\n");
+		if (!firmware_has_feature(FW_FEATURE_CMO))
+			dev_err(hostdata->dev,
+			        "dma_mapping error getting host config\n");
 		free_event_struct(&hostdata->pool, evt_struct);
 		return -1;
 	}
@@ -1604,7 +1614,7 @@ static struct scsi_host_template driver_
 	.eh_host_reset_handler = ibmvscsi_eh_host_reset_handler,
 	.slave_configure = ibmvscsi_slave_configure,
 	.change_queue_depth = ibmvscsi_change_queue_depth,
-	.cmd_per_lun = 16,
+	.cmd_per_lun = IBMVSCSI_CMDS_PER_LUN_DEFAULT,
 	.can_queue = IBMVSCSI_MAX_REQUESTS_DEFAULT,
 	.this_id = -1,
 	.sg_tablesize = SG_ALL,
@@ -1613,6 +1623,26 @@ static struct scsi_host_template driver_
 };
 
 /**
+ * ibmvscsi_get_desired_dma - Calculate IO memory desired by the driver
+ *
+ * @vdev: struct vio_dev for the device whose desired IO mem is to be returned
+ *
+ * Return value:
+ *	Number of bytes of IO data the driver will need to perform well.
+ */
+static unsigned long ibmvscsi_get_desired_dma(struct vio_dev *vdev)
+{
+	/* iu_storage data allocated in initialize_event_pool */
+	unsigned long desired_io = max_requests * sizeof(union viosrp_iu);
+
+	/* add io space for sg data */
+	desired_io += (IBMVSCSI_MAX_SECTORS_DEFAULT *
+	                     IBMVSCSI_CMDS_PER_LUN_DEFAULT);
+
+	return desired_io;
+}
+
+/**
  * Called by bus code for each adapter
  */
 static int ibmvscsi_probe(struct vio_dev *vdev, const struct vio_device_id *id)
@@ -1641,7 +1671,7 @@ static int ibmvscsi_probe(struct vio_dev
 	hostdata->host = host;
 	hostdata->dev = dev;
 	atomic_set(&hostdata->request_limit, -1);
-	hostdata->host->max_sectors = 32 * 8; /* default max I/O 32 pages */
+	hostdata->host->max_sectors = IBMVSCSI_MAX_SECTORS_DEFAULT;
 
 	rc = ibmvscsi_ops->init_crq_queue(&hostdata->queue, hostdata, max_requests);
 	if (rc != 0 && rc != H_RESOURCE) {
@@ -1735,6 +1765,7 @@ static struct vio_driver ibmvscsi_driver
 	.id_table = ibmvscsi_device_table,
 	.probe = ibmvscsi_probe,
 	.remove = ibmvscsi_remove,
+	.get_desired_dma = ibmvscsi_get_desired_dma,
 	.driver = {
 		.name = "ibmvscsi",
 		.owner = THIS_MODULE,
Index: b/drivers/scsi/ibmvscsi/ibmvscsi.h
===================================================================
--- a/drivers/scsi/ibmvscsi/ibmvscsi.h
+++ b/drivers/scsi/ibmvscsi/ibmvscsi.h
@@ -45,6 +45,8 @@ struct Scsi_Host;
 #define MAX_INDIRECT_BUFS 10
 
 #define IBMVSCSI_MAX_REQUESTS_DEFAULT 100
+#define IBMVSCSI_CMDS_PER_LUN_DEFAULT 16
+#define IBMVSCSI_MAX_SECTORS_DEFAULT 256 /* 32 * 8 = default max I/O 32 pages */
 #define IBMVSCSI_MAX_CMDS_PER_LUN 64
 
 /* ------------------------------------------------------------