| /* | |
| * 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. | |
| */ |