| Borislav Petkov | 5ce78af | 2008-02-02 19:56:48 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Ver 0.1 Nov 1 95 Pre-working code :-) |
| 3 | * Ver 0.2 Nov 23 95 A short backup (few megabytes) and restore procedure |
| 4 | * was successful ! (Using tar cvf ... on the block |
| 5 | * device interface). |
| 6 | * A longer backup resulted in major swapping, bad |
| 7 | * overall Linux performance and eventually failed as |
| 8 | * we received non serial read-ahead requests from the |
| 9 | * buffer cache. |
| 10 | * Ver 0.3 Nov 28 95 Long backups are now possible, thanks to the |
| 11 | * character device interface. Linux's responsiveness |
| 12 | * and performance doesn't seem to be much affected |
| 13 | * from the background backup procedure. |
| 14 | * Some general mtio.h magnetic tape operations are |
| 15 | * now supported by our character device. As a result, |
| 16 | * popular tape utilities are starting to work with |
| 17 | * ide tapes :-) |
| 18 | * The following configurations were tested: |
| 19 | * 1. An IDE ATAPI TAPE shares the same interface |
| 20 | * and irq with an IDE ATAPI CDROM. |
| 21 | * 2. An IDE ATAPI TAPE shares the same interface |
| 22 | * and irq with a normal IDE disk. |
| 23 | * Both configurations seemed to work just fine ! |
| 24 | * However, to be on the safe side, it is meanwhile |
| 25 | * recommended to give the IDE TAPE its own interface |
| 26 | * and irq. |
| 27 | * The one thing which needs to be done here is to |
| 28 | * add a "request postpone" feature to ide.c, |
| 29 | * so that we won't have to wait for the tape to finish |
| 30 | * performing a long media access (DSC) request (such |
| 31 | * as a rewind) before we can access the other device |
| 32 | * on the same interface. This effect doesn't disturb |
| 33 | * normal operation most of the time because read/write |
| 34 | * requests are relatively fast, and once we are |
| 35 | * performing one tape r/w request, a lot of requests |
| 36 | * from the other device can be queued and ide.c will |
| 37 | * service all of them after this single tape request. |
| 38 | * Ver 1.0 Dec 11 95 Integrated into Linux 1.3.46 development tree. |
| 39 | * On each read / write request, we now ask the drive |
| 40 | * if we can transfer a constant number of bytes |
| 41 | * (a parameter of the drive) only to its buffers, |
| 42 | * without causing actual media access. If we can't, |
| 43 | * we just wait until we can by polling the DSC bit. |
| 44 | * This ensures that while we are not transferring |
| 45 | * more bytes than the constant referred to above, the |
| 46 | * interrupt latency will not become too high and |
| 47 | * we won't cause an interrupt timeout, as happened |
| 48 | * occasionally in the previous version. |
| 49 | * While polling for DSC, the current request is |
| 50 | * postponed and ide.c is free to handle requests from |
| 51 | * the other device. This is handled transparently to |
| 52 | * ide.c. The hwgroup locking method which was used |
| 53 | * in the previous version was removed. |
| 54 | * Use of new general features which are provided by |
| 55 | * ide.c for use with atapi devices. |
| 56 | * (Programming done by Mark Lord) |
| 57 | * Few potential bug fixes (Again, suggested by Mark) |
| 58 | * Single character device data transfers are now |
| 59 | * not limited in size, as they were before. |
| 60 | * We are asking the tape about its recommended |
| 61 | * transfer unit and send a larger data transfer |
| 62 | * as several transfers of the above size. |
| 63 | * For best results, use an integral number of this |
| 64 | * basic unit (which is shown during driver |
| 65 | * initialization). I will soon add an ioctl to get |
| 66 | * this important parameter. |
| 67 | * Our data transfer buffer is allocated on startup, |
| 68 | * rather than before each data transfer. This should |
| 69 | * ensure that we will indeed have a data buffer. |
| 70 | * Ver 1.1 Dec 14 95 Fixed random problems which occurred when the tape |
| 71 | * shared an interface with another device. |
| 72 | * (poll_for_dsc was a complete mess). |
| 73 | * Removed some old (non-active) code which had |
| 74 | * to do with supporting buffer cache originated |
| 75 | * requests. |
| 76 | * The block device interface can now be opened, so |
| 77 | * that general ide driver features like the unmask |
| 78 | * interrupts flag can be selected with an ioctl. |
| 79 | * This is the only use of the block device interface. |
| 80 | * New fast pipelined operation mode (currently only on |
| 81 | * writes). When using the pipelined mode, the |
| 82 | * throughput can potentially reach the maximum |
| 83 | * tape supported throughput, regardless of the |
| 84 | * user backup program. On my tape drive, it sometimes |
| 85 | * boosted performance by a factor of 2. Pipelined |
| 86 | * mode is enabled by default, but since it has a few |
| 87 | * downfalls as well, you may want to disable it. |
| 88 | * A short explanation of the pipelined operation mode |
| 89 | * is available below. |
| 90 | * Ver 1.2 Jan 1 96 Eliminated pipelined mode race condition. |
| 91 | * Added pipeline read mode. As a result, restores |
| 92 | * are now as fast as backups. |
| 93 | * Optimized shared interface behavior. The new behavior |
| 94 | * typically results in better IDE bus efficiency and |
| 95 | * higher tape throughput. |
| 96 | * Pre-calculation of the expected read/write request |
| 97 | * service time, based on the tape's parameters. In |
| 98 | * the pipelined operation mode, this allows us to |
| 99 | * adjust our polling frequency to a much lower value, |
| 100 | * and thus to dramatically reduce our load on Linux, |
| 101 | * without any decrease in performance. |
| 102 | * Implemented additional mtio.h operations. |
| 103 | * The recommended user block size is returned by |
| 104 | * the MTIOCGET ioctl. |
| 105 | * Additional minor changes. |
| 106 | * Ver 1.3 Feb 9 96 Fixed pipelined read mode bug which prevented the |
| 107 | * use of some block sizes during a restore procedure. |
| 108 | * The character device interface will now present a |
| 109 | * continuous view of the media - any mix of block sizes |
| 110 | * during a backup/restore procedure is supported. The |
| 111 | * driver will buffer the requests internally and |
| 112 | * convert them to the tape's recommended transfer |
| 113 | * unit, making performance almost independent of the |
| 114 | * chosen user block size. |
| 115 | * Some improvements in error recovery. |
| 116 | * By cooperating with ide-dma.c, bus mastering DMA can |
| 117 | * now sometimes be used with IDE tape drives as well. |
| 118 | * Bus mastering DMA has the potential to dramatically |
| 119 | * reduce the CPU's overhead when accessing the device, |
| 120 | * and can be enabled by using hdparm -d1 on the tape's |
| 121 | * block device interface. For more info, read the |
| 122 | * comments in ide-dma.c. |
| 123 | * Ver 1.4 Mar 13 96 Fixed serialize support. |
| 124 | * Ver 1.5 Apr 12 96 Fixed shared interface operation, broken in 1.3.85. |
| 125 | * Fixed pipelined read mode inefficiency. |
| 126 | * Fixed nasty null dereferencing bug. |
| 127 | * Ver 1.6 Aug 16 96 Fixed FPU usage in the driver. |
| 128 | * Fixed end of media bug. |
| 129 | * Ver 1.7 Sep 10 96 Minor changes for the CONNER CTT8000-A model. |
| 130 | * Ver 1.8 Sep 26 96 Attempt to find a better balance between good |
| 131 | * interactive response and high system throughput. |
| 132 | * Ver 1.9 Nov 5 96 Automatically cross encountered filemarks rather |
| 133 | * than requiring an explicit FSF command. |
| 134 | * Abort pending requests at end of media. |
| 135 | * MTTELL was sometimes returning incorrect results. |
| 136 | * Return the real block size in the MTIOCGET ioctl. |
| 137 | * Some error recovery bug fixes. |
| 138 | * Ver 1.10 Nov 5 96 Major reorganization. |
| 139 | * Reduced CPU overhead a bit by eliminating internal |
| 140 | * bounce buffers. |
| 141 | * Added module support. |
| 142 | * Added multiple tape drives support. |
| 143 | * Added partition support. |
| 144 | * Rewrote DSC handling. |
| 145 | * Some portability fixes. |
| 146 | * Removed ide-tape.h. |
| 147 | * Additional minor changes. |
| 148 | * Ver 1.11 Dec 2 96 Bug fix in previous DSC timeout handling. |
| 149 | * Use ide_stall_queue() for DSC overlap. |
| 150 | * Use the maximum speed rather than the current speed |
| 151 | * to compute the request service time. |
| 152 | * Ver 1.12 Dec 7 97 Fix random memory overwriting and/or last block data |
| 153 | * corruption, which could occur if the total number |
| 154 | * of bytes written to the tape was not an integral |
| 155 | * number of tape blocks. |
| 156 | * Add support for INTERRUPT DRQ devices. |
| 157 | * Ver 1.13 Jan 2 98 Add "speed == 0" work-around for HP COLORADO 5GB |
| 158 | * Ver 1.14 Dec 30 98 Partial fixes for the Sony/AIWA tape drives. |
| 159 | * Replace cli()/sti() with hwgroup spinlocks. |
| 160 | * Ver 1.15 Mar 25 99 Fix SMP race condition by replacing hwgroup |
| 161 | * spinlock with private per-tape spinlock. |
| 162 | * Ver 1.16 Sep 1 99 Add OnStream tape support. |
| 163 | * Abort read pipeline on EOD. |
| 164 | * Wait for the tape to become ready in case it returns |
| 165 | * "in the process of becoming ready" on open(). |
| 166 | * Fix zero padding of the last written block in |
| 167 | * case the tape block size is larger than PAGE_SIZE. |
| 168 | * Decrease the default disconnection time to tn. |
| 169 | * Ver 1.16e Oct 3 99 Minor fixes. |
| 170 | * Ver 1.16e1 Oct 13 99 Patches by Arnold Niessen, |
| 171 | * niessen@iae.nl / arnold.niessen@philips.com |
| 172 | * GO-1) Undefined code in idetape_read_position |
| 173 | * according to Gadi's email |
| 174 | * AJN-1) Minor fix asc == 11 should be asc == 0x11 |
| 175 | * in idetape_issue_packet_command (did effect |
| 176 | * debugging output only) |
| 177 | * AJN-2) Added more debugging output, and |
| 178 | * added ide-tape: where missing. I would also |
| 179 | * like to add tape->name where possible |
| 180 | * AJN-3) Added different debug_level's |
| 181 | * via /proc/ide/hdc/settings |
| 182 | * "debug_level" determines amount of debugging output; |
| 183 | * can be changed using /proc/ide/hdx/settings |
| 184 | * 0 : almost no debugging output |
| 185 | * 1 : 0+output errors only |
| 186 | * 2 : 1+output all sensekey/asc |
| 187 | * 3 : 2+follow all chrdev related procedures |
| 188 | * 4 : 3+follow all procedures |
| 189 | * 5 : 4+include pc_stack rq_stack info |
| 190 | * 6 : 5+USE_COUNT updates |
| 191 | * AJN-4) Fixed timeout for retension in idetape_queue_pc_tail |
| 192 | * from 5 to 10 minutes |
| 193 | * AJN-5) Changed maximum number of blocks to skip when |
| 194 | * reading tapes with multiple consecutive write |
| 195 | * errors from 100 to 1000 in idetape_get_logical_blk |
| 196 | * Proposed changes to code: |
| 197 | * 1) output "logical_blk_num" via /proc |
| 198 | * 2) output "current_operation" via /proc |
| 199 | * 3) Either solve or document the fact that `mt rewind' is |
| 200 | * required after reading from /dev/nhtx to be |
| 201 | * able to rmmod the idetape module; |
| 202 | * Also, sometimes an application finishes but the |
| 203 | * device remains `busy' for some time. Same cause ? |
| 204 | * Proposed changes to release-notes: |
| 205 | * 4) write a simple `quickstart' section in the |
| 206 | * release notes; I volunteer if you don't want to |
| 207 | * 5) include a pointer to video4linux in the doc |
| 208 | * to stimulate video applications |
| 209 | * 6) release notes lines 331 and 362: explain what happens |
| 210 | * if the application data rate is higher than 1100 KB/s; |
| 211 | * similar approach to lower-than-500 kB/s ? |
| 212 | * 7) 6.6 Comparison; wouldn't it be better to allow different |
| 213 | * strategies for read and write ? |
| 214 | * Wouldn't it be better to control the tape buffer |
| 215 | * contents instead of the bandwidth ? |
| 216 | * 8) line 536: replace will by would (if I understand |
| 217 | * this section correctly, a hypothetical and unwanted situation |
| 218 | * is being described) |
| 219 | * Ver 1.16f Dec 15 99 Change place of the secondary OnStream header frames. |
| 220 | * Ver 1.17 Nov 2000 / Jan 2001 Marcel Mol, marcel@mesa.nl |
| 221 | * - Add idetape_onstream_mode_sense_tape_parameter_page |
| 222 | * function to get tape capacity in frames: tape->capacity. |
| 223 | * - Add support for DI-50 drives( or any DI- drive). |
| 224 | * - 'workaround' for read error/blank block around block 3000. |
| 225 | * - Implement Early warning for end of media for Onstream. |
| 226 | * - Cosmetic code changes for readability. |
| 227 | * - Idetape_position_tape should not use SKIP bit during |
| 228 | * Onstream read recovery. |
| 229 | * - Add capacity, logical_blk_num and first/last_frame_position |
| 230 | * to /proc/ide/hd?/settings. |
| 231 | * - Module use count was gone in the Linux 2.4 driver. |
| 232 | * Ver 1.17a Apr 2001 Willem Riede osst@riede.org |
| 233 | * - Get drive's actual block size from mode sense block descriptor |
| 234 | * - Limit size of pipeline |
| 235 | * Ver 1.17b Oct 2002 Alan Stern <stern@rowland.harvard.edu> |
| 236 | * Changed IDETAPE_MIN_PIPELINE_STAGES to 1 and actually used |
| 237 | * it in the code! |
| 238 | * Actually removed aborted stages in idetape_abort_pipeline |
| 239 | * instead of just changing the command code. |
| 240 | * Made the transfer byte count for Request Sense equal to the |
| 241 | * actual length of the data transfer. |
| 242 | * Changed handling of partial data transfers: they do not |
| 243 | * cause DMA errors. |
| 244 | * Moved initiation of DMA transfers to the correct place. |
| 245 | * Removed reference to unallocated memory. |
| 246 | * Made __idetape_discard_read_pipeline return the number of |
| 247 | * sectors skipped, not the number of stages. |
| 248 | * Replaced errant kfree() calls with __idetape_kfree_stage(). |
| 249 | * Fixed off-by-one error in testing the pipeline length. |
| 250 | * Fixed handling of filemarks in the read pipeline. |
| 251 | * Small code optimization for MTBSF and MTBSFM ioctls. |
| 252 | * Don't try to unlock the door during device close if is |
| 253 | * already unlocked! |
| 254 | * Cosmetic fixes to miscellaneous debugging output messages. |
| 255 | * Set the minimum /proc/ide/hd?/settings values for "pipeline", |
| 256 | * "pipeline_min", and "pipeline_max" to 1. |
| 257 | */ |