5ce78af4be
Also, cleanup whitespace and update comments. Bart: - remove reference to drivers/block/ide.c - move driver documentation to Documentation/ide/ide-tape.txt Signed-off-by: Borislav Petkov <bbpetkov@yahoo.de> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
258 lines
16 KiB
Plaintext
258 lines
16 KiB
Plaintext
/*
|
|
* Ver 0.1 Nov 1 95 Pre-working code :-)
|
|
* Ver 0.2 Nov 23 95 A short backup (few megabytes) and restore procedure
|
|
* was successful ! (Using tar cvf ... on the block
|
|
* device interface).
|
|
* A longer backup resulted in major swapping, bad
|
|
* overall Linux performance and eventually failed as
|
|
* we received non serial read-ahead requests from the
|
|
* buffer cache.
|
|
* Ver 0.3 Nov 28 95 Long backups are now possible, thanks to the
|
|
* character device interface. Linux's responsiveness
|
|
* and performance doesn't seem to be much affected
|
|
* from the background backup procedure.
|
|
* Some general mtio.h magnetic tape operations are
|
|
* now supported by our character device. As a result,
|
|
* popular tape utilities are starting to work with
|
|
* ide tapes :-)
|
|
* The following configurations were tested:
|
|
* 1. An IDE ATAPI TAPE shares the same interface
|
|
* and irq with an IDE ATAPI CDROM.
|
|
* 2. An IDE ATAPI TAPE shares the same interface
|
|
* and irq with a normal IDE disk.
|
|
* Both configurations seemed to work just fine !
|
|
* However, to be on the safe side, it is meanwhile
|
|
* recommended to give the IDE TAPE its own interface
|
|
* and irq.
|
|
* The one thing which needs to be done here is to
|
|
* add a "request postpone" feature to ide.c,
|
|
* so that we won't have to wait for the tape to finish
|
|
* performing a long media access (DSC) request (such
|
|
* as a rewind) before we can access the other device
|
|
* on the same interface. This effect doesn't disturb
|
|
* normal operation most of the time because read/write
|
|
* requests are relatively fast, and once we are
|
|
* performing one tape r/w request, a lot of requests
|
|
* from the other device can be queued and ide.c will
|
|
* service all of them after this single tape request.
|
|
* Ver 1.0 Dec 11 95 Integrated into Linux 1.3.46 development tree.
|
|
* On each read / write request, we now ask the drive
|
|
* if we can transfer a constant number of bytes
|
|
* (a parameter of the drive) only to its buffers,
|
|
* without causing actual media access. If we can't,
|
|
* we just wait until we can by polling the DSC bit.
|
|
* This ensures that while we are not transferring
|
|
* more bytes than the constant referred to above, the
|
|
* interrupt latency will not become too high and
|
|
* we won't cause an interrupt timeout, as happened
|
|
* occasionally in the previous version.
|
|
* While polling for DSC, the current request is
|
|
* postponed and ide.c is free to handle requests from
|
|
* the other device. This is handled transparently to
|
|
* ide.c. The hwgroup locking method which was used
|
|
* in the previous version was removed.
|
|
* Use of new general features which are provided by
|
|
* ide.c for use with atapi devices.
|
|
* (Programming done by Mark Lord)
|
|
* Few potential bug fixes (Again, suggested by Mark)
|
|
* Single character device data transfers are now
|
|
* not limited in size, as they were before.
|
|
* We are asking the tape about its recommended
|
|
* transfer unit and send a larger data transfer
|
|
* as several transfers of the above size.
|
|
* For best results, use an integral number of this
|
|
* basic unit (which is shown during driver
|
|
* initialization). I will soon add an ioctl to get
|
|
* this important parameter.
|
|
* Our data transfer buffer is allocated on startup,
|
|
* rather than before each data transfer. This should
|
|
* ensure that we will indeed have a data buffer.
|
|
* Ver 1.1 Dec 14 95 Fixed random problems which occurred when the tape
|
|
* shared an interface with another device.
|
|
* (poll_for_dsc was a complete mess).
|
|
* Removed some old (non-active) code which had
|
|
* to do with supporting buffer cache originated
|
|
* requests.
|
|
* The block device interface can now be opened, so
|
|
* that general ide driver features like the unmask
|
|
* interrupts flag can be selected with an ioctl.
|
|
* This is the only use of the block device interface.
|
|
* New fast pipelined operation mode (currently only on
|
|
* writes). When using the pipelined mode, the
|
|
* throughput can potentially reach the maximum
|
|
* tape supported throughput, regardless of the
|
|
* user backup program. On my tape drive, it sometimes
|
|
* boosted performance by a factor of 2. Pipelined
|
|
* mode is enabled by default, but since it has a few
|
|
* downfalls as well, you may want to disable it.
|
|
* A short explanation of the pipelined operation mode
|
|
* is available below.
|
|
* Ver 1.2 Jan 1 96 Eliminated pipelined mode race condition.
|
|
* Added pipeline read mode. As a result, restores
|
|
* are now as fast as backups.
|
|
* Optimized shared interface behavior. The new behavior
|
|
* typically results in better IDE bus efficiency and
|
|
* higher tape throughput.
|
|
* Pre-calculation of the expected read/write request
|
|
* service time, based on the tape's parameters. In
|
|
* the pipelined operation mode, this allows us to
|
|
* adjust our polling frequency to a much lower value,
|
|
* and thus to dramatically reduce our load on Linux,
|
|
* without any decrease in performance.
|
|
* Implemented additional mtio.h operations.
|
|
* The recommended user block size is returned by
|
|
* the MTIOCGET ioctl.
|
|
* Additional minor changes.
|
|
* Ver 1.3 Feb 9 96 Fixed pipelined read mode bug which prevented the
|
|
* use of some block sizes during a restore procedure.
|
|
* The character device interface will now present a
|
|
* continuous view of the media - any mix of block sizes
|
|
* during a backup/restore procedure is supported. The
|
|
* driver will buffer the requests internally and
|
|
* convert them to the tape's recommended transfer
|
|
* unit, making performance almost independent of the
|
|
* chosen user block size.
|
|
* Some improvements in error recovery.
|
|
* By cooperating with ide-dma.c, bus mastering DMA can
|
|
* now sometimes be used with IDE tape drives as well.
|
|
* Bus mastering DMA has the potential to dramatically
|
|
* reduce the CPU's overhead when accessing the device,
|
|
* and can be enabled by using hdparm -d1 on the tape's
|
|
* block device interface. For more info, read the
|
|
* comments in ide-dma.c.
|
|
* Ver 1.4 Mar 13 96 Fixed serialize support.
|
|
* Ver 1.5 Apr 12 96 Fixed shared interface operation, broken in 1.3.85.
|
|
* Fixed pipelined read mode inefficiency.
|
|
* Fixed nasty null dereferencing bug.
|
|
* Ver 1.6 Aug 16 96 Fixed FPU usage in the driver.
|
|
* Fixed end of media bug.
|
|
* Ver 1.7 Sep 10 96 Minor changes for the CONNER CTT8000-A model.
|
|
* Ver 1.8 Sep 26 96 Attempt to find a better balance between good
|
|
* interactive response and high system throughput.
|
|
* Ver 1.9 Nov 5 96 Automatically cross encountered filemarks rather
|
|
* than requiring an explicit FSF command.
|
|
* Abort pending requests at end of media.
|
|
* MTTELL was sometimes returning incorrect results.
|
|
* Return the real block size in the MTIOCGET ioctl.
|
|
* Some error recovery bug fixes.
|
|
* Ver 1.10 Nov 5 96 Major reorganization.
|
|
* Reduced CPU overhead a bit by eliminating internal
|
|
* bounce buffers.
|
|
* Added module support.
|
|
* Added multiple tape drives support.
|
|
* Added partition support.
|
|
* Rewrote DSC handling.
|
|
* Some portability fixes.
|
|
* Removed ide-tape.h.
|
|
* Additional minor changes.
|
|
* Ver 1.11 Dec 2 96 Bug fix in previous DSC timeout handling.
|
|
* Use ide_stall_queue() for DSC overlap.
|
|
* Use the maximum speed rather than the current speed
|
|
* to compute the request service time.
|
|
* Ver 1.12 Dec 7 97 Fix random memory overwriting and/or last block data
|
|
* corruption, which could occur if the total number
|
|
* of bytes written to the tape was not an integral
|
|
* number of tape blocks.
|
|
* Add support for INTERRUPT DRQ devices.
|
|
* Ver 1.13 Jan 2 98 Add "speed == 0" work-around for HP COLORADO 5GB
|
|
* Ver 1.14 Dec 30 98 Partial fixes for the Sony/AIWA tape drives.
|
|
* Replace cli()/sti() with hwgroup spinlocks.
|
|
* Ver 1.15 Mar 25 99 Fix SMP race condition by replacing hwgroup
|
|
* spinlock with private per-tape spinlock.
|
|
* Ver 1.16 Sep 1 99 Add OnStream tape support.
|
|
* Abort read pipeline on EOD.
|
|
* Wait for the tape to become ready in case it returns
|
|
* "in the process of becoming ready" on open().
|
|
* Fix zero padding of the last written block in
|
|
* case the tape block size is larger than PAGE_SIZE.
|
|
* Decrease the default disconnection time to tn.
|
|
* Ver 1.16e Oct 3 99 Minor fixes.
|
|
* Ver 1.16e1 Oct 13 99 Patches by Arnold Niessen,
|
|
* niessen@iae.nl / arnold.niessen@philips.com
|
|
* GO-1) Undefined code in idetape_read_position
|
|
* according to Gadi's email
|
|
* AJN-1) Minor fix asc == 11 should be asc == 0x11
|
|
* in idetape_issue_packet_command (did effect
|
|
* debugging output only)
|
|
* AJN-2) Added more debugging output, and
|
|
* added ide-tape: where missing. I would also
|
|
* like to add tape->name where possible
|
|
* AJN-3) Added different debug_level's
|
|
* via /proc/ide/hdc/settings
|
|
* "debug_level" determines amount of debugging output;
|
|
* can be changed using /proc/ide/hdx/settings
|
|
* 0 : almost no debugging output
|
|
* 1 : 0+output errors only
|
|
* 2 : 1+output all sensekey/asc
|
|
* 3 : 2+follow all chrdev related procedures
|
|
* 4 : 3+follow all procedures
|
|
* 5 : 4+include pc_stack rq_stack info
|
|
* 6 : 5+USE_COUNT updates
|
|
* AJN-4) Fixed timeout for retension in idetape_queue_pc_tail
|
|
* from 5 to 10 minutes
|
|
* AJN-5) Changed maximum number of blocks to skip when
|
|
* reading tapes with multiple consecutive write
|
|
* errors from 100 to 1000 in idetape_get_logical_blk
|
|
* Proposed changes to code:
|
|
* 1) output "logical_blk_num" via /proc
|
|
* 2) output "current_operation" via /proc
|
|
* 3) Either solve or document the fact that `mt rewind' is
|
|
* required after reading from /dev/nhtx to be
|
|
* able to rmmod the idetape module;
|
|
* Also, sometimes an application finishes but the
|
|
* device remains `busy' for some time. Same cause ?
|
|
* Proposed changes to release-notes:
|
|
* 4) write a simple `quickstart' section in the
|
|
* release notes; I volunteer if you don't want to
|
|
* 5) include a pointer to video4linux in the doc
|
|
* to stimulate video applications
|
|
* 6) release notes lines 331 and 362: explain what happens
|
|
* if the application data rate is higher than 1100 KB/s;
|
|
* similar approach to lower-than-500 kB/s ?
|
|
* 7) 6.6 Comparison; wouldn't it be better to allow different
|
|
* strategies for read and write ?
|
|
* Wouldn't it be better to control the tape buffer
|
|
* contents instead of the bandwidth ?
|
|
* 8) line 536: replace will by would (if I understand
|
|
* this section correctly, a hypothetical and unwanted situation
|
|
* is being described)
|
|
* Ver 1.16f Dec 15 99 Change place of the secondary OnStream header frames.
|
|
* Ver 1.17 Nov 2000 / Jan 2001 Marcel Mol, marcel@mesa.nl
|
|
* - Add idetape_onstream_mode_sense_tape_parameter_page
|
|
* function to get tape capacity in frames: tape->capacity.
|
|
* - Add support for DI-50 drives( or any DI- drive).
|
|
* - 'workaround' for read error/blank block around block 3000.
|
|
* - Implement Early warning for end of media for Onstream.
|
|
* - Cosmetic code changes for readability.
|
|
* - Idetape_position_tape should not use SKIP bit during
|
|
* Onstream read recovery.
|
|
* - Add capacity, logical_blk_num and first/last_frame_position
|
|
* to /proc/ide/hd?/settings.
|
|
* - Module use count was gone in the Linux 2.4 driver.
|
|
* Ver 1.17a Apr 2001 Willem Riede osst@riede.org
|
|
* - Get drive's actual block size from mode sense block descriptor
|
|
* - Limit size of pipeline
|
|
* Ver 1.17b Oct 2002 Alan Stern <stern@rowland.harvard.edu>
|
|
* Changed IDETAPE_MIN_PIPELINE_STAGES to 1 and actually used
|
|
* it in the code!
|
|
* Actually removed aborted stages in idetape_abort_pipeline
|
|
* instead of just changing the command code.
|
|
* Made the transfer byte count for Request Sense equal to the
|
|
* actual length of the data transfer.
|
|
* Changed handling of partial data transfers: they do not
|
|
* cause DMA errors.
|
|
* Moved initiation of DMA transfers to the correct place.
|
|
* Removed reference to unallocated memory.
|
|
* Made __idetape_discard_read_pipeline return the number of
|
|
* sectors skipped, not the number of stages.
|
|
* Replaced errant kfree() calls with __idetape_kfree_stage().
|
|
* Fixed off-by-one error in testing the pipeline length.
|
|
* Fixed handling of filemarks in the read pipeline.
|
|
* Small code optimization for MTBSF and MTBSFM ioctls.
|
|
* Don't try to unlock the door during device close if is
|
|
* already unlocked!
|
|
* Cosmetic fixes to miscellaneous debugging output messages.
|
|
* Set the minimum /proc/ide/hd?/settings values for "pipeline",
|
|
* "pipeline_min", and "pipeline_max" to 1.
|
|
*/
|