/* * 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 * 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. */