-/*
- * IDE ATAPI streaming tape driver.
- *
- * This driver is a part of the Linux ide driver.
- *
- * The driver, in co-operation with ide.c, basically traverses the
- * request-list for the block device interface. The character device
- * interface, on the other hand, creates new requests, adds them
- * to the request-list of the block device, and waits for their completion.
- *
- * The block device major and minor numbers are determined from the
- * tape's relative position in the ide interfaces, as explained in ide.c.
- *
- * The character device interface consists of the following devices:
- *
- * ht0 major 37, minor 0 first IDE tape, rewind on close.
- * ht1 major 37, minor 1 second IDE tape, rewind on close.
- * ...
- * nht0 major 37, minor 128 first IDE tape, no rewind on close.
- * nht1 major 37, minor 129 second IDE tape, no rewind on close.
- * ...
- *
- * The general magnetic tape commands compatible interface, as defined by
- * include/linux/mtio.h, is accessible through the character device.
- *
- * General ide driver configuration options, such as the interrupt-unmask
- * flag, can be configured by issuing an ioctl to the block device interface,
- * as any other ide device.
- *
- * Our own ide-tape ioctl's can be issued to either the block device or
- * the character device interface.
- *
- * Maximal throughput with minimal bus load will usually be achieved in the
- * following scenario:
- *
- * 1. ide-tape is operating in the pipelined operation mode.
- * 2. No buffering is performed by the user backup program.
- *
- * Testing was done with a 2 GB CONNER CTMA 4000 IDE ATAPI Streaming Tape Drive.
- *
- * Here are some words from the first releases of hd.c, which are quoted
- * in ide.c and apply here as well:
- *
- * | Special care is recommended. Have Fun!
- *
- * Possible improvements.
- *
- * 1. Support for the ATAPI overlap protocol.
- *
- * In order to maximize bus throughput, we currently use the DSC
- * overlap method which enables ide.c to service requests from the
- * other device while the tape is busy executing a command. The
- * DSC overlap method involves polling the tape's status register
- * for the DSC bit, and servicing the other device while the tape
- * isn't ready.
- *
- * In the current QIC development standard (December 1995),
- * it is recommended that new tape drives will *in addition*
- * implement the ATAPI overlap protocol, which is used for the
- * same purpose - efficient use of the IDE bus, but is interrupt
- * driven and thus has much less CPU overhead.
- *
- * ATAPI overlap is likely to be supported in most new ATAPI
- * devices, including new ATAPI cdroms, and thus provides us
- * a method by which we can achieve higher throughput when
- * sharing a (fast) ATA-2 disk with any (slow) new ATAPI device.
- */
+IDE ATAPI streaming tape driver.
+
+This driver is a part of the Linux ide driver.
+
+The driver, in co-operation with ide.c, basically traverses the
+request-list for the block device interface. The character device
+interface, on the other hand, creates new requests, adds them
+to the request-list of the block device, and waits for their completion.
+
+The block device major and minor numbers are determined from the
+tape's relative position in the ide interfaces, as explained in ide.c.
+
+The character device interface consists of the following devices:
+
+ht0 major 37, minor 0 first IDE tape, rewind on close.
+ht1 major 37, minor 1 second IDE tape, rewind on close.
+...
+nht0 major 37, minor 128 first IDE tape, no rewind on close.
+nht1 major 37, minor 129 second IDE tape, no rewind on close.
+...
+
+The general magnetic tape commands compatible interface, as defined by
+include/linux/mtio.h, is accessible through the character device.
+
+General ide driver configuration options, such as the interrupt-unmask
+flag, can be configured by issuing an ioctl to the block device interface,
+as any other ide device.
+
+Our own ide-tape ioctl's can be issued to either the block device or
+the character device interface.
+
+Maximal throughput with minimal bus load will usually be achieved in the
+following scenario:
+
+ 1. ide-tape is operating in the pipelined operation mode.
+ 2. No buffering is performed by the user backup program.
+
+Testing was done with a 2 GB CONNER CTMA 4000 IDE ATAPI Streaming Tape Drive.
+
+Here are some words from the first releases of hd.c, which are quoted
+in ide.c and apply here as well:
+
+| Special care is recommended. Have Fun!
+
+Possible improvements:
+
+1. Support for the ATAPI overlap protocol.
+
+In order to maximize bus throughput, we currently use the DSC
+overlap method which enables ide.c to service requests from the
+other device while the tape is busy executing a command. The
+DSC overlap method involves polling the tape's status register
+for the DSC bit, and servicing the other device while the tape
+isn't ready.
+
+In the current QIC development standard (December 1995),
+it is recommended that new tape drives will *in addition*
+implement the ATAPI overlap protocol, which is used for the
+same purpose - efficient use of the IDE bus, but is interrupt
+driven and thus has much less CPU overhead.
+
+ATAPI overlap is likely to be supported in most new ATAPI
+devices, including new ATAPI cdroms, and thus provides us
+a method by which we can achieve higher throughput when
+sharing a (fast) ATA-2 disk with any (slow) new ATAPI device.
projects / linux-2.6 / commitdiff