# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher.
# This patch includes the following deltas:
#	           ChangeSet	1.166   -> 1.167  
#	   drivers/scsi/sd.c	1.18    -> 1.19   
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 02/02/28	jejb@malley.il.steeleye.com	1.167
# changes in sd driver
# 
# Drive cache set to write back if possible.
# --------------------------------------------
#
diff -Nru a/drivers/scsi/sd.c b/drivers/scsi/sd.c
--- a/drivers/scsi/sd.c	Thu Feb 28 20:04:49 2002
+++ b/drivers/scsi/sd.c	Thu Feb 28 20:04:49 2002
@@ -741,7 +741,7 @@
 	char nbuff[6];
 	unsigned char *buffer;
 	unsigned long spintime_value = 0;
-	int the_result, retries, spintime;
+	int the_result, retries, spintime, mode_retries;
 	int sector_size;
 	Scsi_Request *SRpnt;
 
@@ -858,6 +858,105 @@
 		else
 			printk("ready\n");
 	}
+
+	mode_retries = 2;	/* make two attempts to change the cache type */
+
+ retry_mode_select:
+	retries = 3;
+	do {
+
+		memset((void *) &cmd[0], 0, 10);
+		cmd[0] = MODE_SENSE;
+		cmd[1] = (rscsi_disks[i].device->scsi_level <= SCSI_2) ?
+			 ((rscsi_disks[i].device->lun << 5) & 0xe0) : 0;
+		cmd[1] |= 0x08;	/* DBD */
+		cmd[2] = 0x08;	/* current values, cache page */
+		cmd[4] = 24;	/* allocation length */
+
+
+		memset((void *) buffer, 0, 24);
+		SRpnt->sr_cmd_len = 0;
+		SRpnt->sr_sense_buffer[0] = 0;
+		SRpnt->sr_sense_buffer[2] = 0;
+
+		SRpnt->sr_data_direction = SCSI_DATA_READ;
+		scsi_wait_req(SRpnt, (void *) cmd, (void *) buffer,
+			    24, SD_TIMEOUT, MAX_RETRIES);
+
+		the_result = SRpnt->sr_result;
+		retries--;
+
+	} while (the_result && retries);
+
+	if (the_result) {
+		printk("%s : MODE SENSE failed.\n"
+		       "%s : status = %x, message = %02x, host = %d, driver = %02x \n",
+		       nbuff, nbuff,
+		       status_byte(the_result),
+		       msg_byte(the_result),
+		       host_byte(the_result),
+		       driver_byte(the_result)
+		    );
+		if (driver_byte(the_result) & DRIVER_SENSE)
+			print_req_sense("sd", SRpnt);
+		else
+			printk("%s : sense not available. \n", nbuff);
+	} else {
+		const char *types[] = { "write through", "none", "write back", "write back, no read (daft)" };
+		int ct = 0;
+
+		ct = (buffer[6] & 0x01 /* RCD */) | ((buffer[6] & 0x04 /* WCE */) >> 1);
+
+		printk("%s : checking drive cache: %s \n", nbuff, types[ct]);
+		if(ct != 0x0 && mode_retries-- == 0) {
+			printk("%s : FAILED to change cache to write back, continuing\n", nbuff);
+		}
+		else if(ct != 0x0) {
+			retries = 3;
+			buffer[6] &= (~0x05); /* clear RCD and WCE */
+			do {
+				memset((void *) &cmd[0], 0, 10);
+				cmd[0] = MODE_SELECT;
+				cmd[1] = (rscsi_disks[i].device->scsi_level <= SCSI_2) ?
+					((rscsi_disks[i].device->lun << 5) & 0xe0) : 0;
+				cmd[1] |= 0x10;	/* PF */
+				cmd[4] = 24;	/* allocation length */
+				
+				
+				SRpnt->sr_cmd_len = 0;
+				SRpnt->sr_sense_buffer[0] = 0;
+				SRpnt->sr_sense_buffer[2] = 0;
+				
+				SRpnt->sr_data_direction = SCSI_DATA_WRITE;
+				scsi_wait_req(SRpnt, (void *) cmd, (void *) buffer,
+					      24, SD_TIMEOUT, MAX_RETRIES);
+
+				the_result = SRpnt->sr_result;
+				retries--;
+
+			} while (the_result && retries);
+
+			if (the_result) {
+				printk("%s : MODE SELECT failed.\n"
+				       "%s : status = %x, message = %02x, host = %d, driver = %02x \n",
+				       nbuff, nbuff,
+				       status_byte(the_result),
+				       msg_byte(the_result),
+				       host_byte(the_result),
+				       driver_byte(the_result)
+				       );
+				if (driver_byte(the_result) & DRIVER_SENSE)
+					print_req_sense("sd", SRpnt);
+				else
+					printk("%s : sense not available. \n", nbuff);
+			} else {
+				printk("%s : changing drive cache to write through\n", nbuff);
+			}
+			goto retry_mode_select;
+		}
+		
+	}
+
 	retries = 3;
 	do {
 		cmd[0] = READ_CAPACITY;