patch-2.1.127 linux/drivers/scsi/README.tmscsim

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+The tmscsim driver
+==================
+
+1. Purpose and history
+2. Installation
+3. Features
+4. Configuration via /proc/scsi/tmscsim/?
+5. Configuration via boot/module params
+6. Potential improvements
+7. Bug reports, debugging and updates
+8. Acknowledgements
+
+
+1. Purpose and history
+----------------------
+The tmscsim driver supports PCI SCSI Host Adapters based on the AM53C974
+chip. AM53C974 based SCSI adapters include: 
+ Tekram DC390, DC390T
+ Dawicontrol 2974
+ some on-board adapters
+(This is most probably not a complete list)
+
+It has originally written by C.L. Huang from the Tekram corp. to support the
+Tekram DC390(T) adapter. This is where the name comes from: tm = Tekram
+scsi = SCSI driver, m = AMD (?) as opposed to w for the DC390W/U/F
+(NCR53c8X5, X=2/7) driver. Yes, there was also a driver for the latter,
+tmscsimw, which supported DC390W/U/F adapters. It's not maintained any more,
+as the ncr53c8xx is perfectly supporting these adpaters since some time.
+
+The driver first appeared in April 1996, exclusively supported the DC390 
+and has been enhanced since then in various steps. In May 1998 support for 
+general AM53C974 based adapters and some possibilities to configure it were
+added. The non-DC390 support works by assuming some values for the data
+normally taken from the DC390 EEPROM. See below (chapter 5) for details.
+
+When using the DC390, the configuration is still be done using the DC390
+BIOS setup. The DC390 EEPROM is read and used by the driver, any boot or
+module parameters (chapter 5) are ignored! However, you can change settings
+dynamically, as described in chapter 4. 
+
+For a more detailed description of the driver's history, see the first lines
+of tmscsim.c.
+The numbering scheme isn't consistent. The first versions went from 1.00 to
+1.12, then 1.20a to 1.20t. Finally I decided to use the ncr53c8xx scheme. So
+the next revisions will be 2.0a to 2.0X (stable), 2.1a to 2.1X (experimental),
+2.2a to 2.2X (stable, again) etc. (X = anything between a and z.) If I send
+fixes to people for testing, those will have a digit appended, e.g. 2.0a1.
+
+
+2. Installation
+---------------
+If you got any recent kernel with this driver and document included in
+linux/drivers/scsi, you basically have to do nothing special to use this
+driver. Of course you have to choose to compile SCSI support and DC390(T)
+support into your kernel or as module when configuring your kernel for
+compiling.
+
+If you got an older kernel with an old version of this driver included, you
+should copy the files (dc390.h, tmscsim.h, tmscsim.c, scsiiom.c and
+README.tmscsim) from this directory to linux/drivers/scsi. You have to
+recompile your kernel/module of course.
+
+You should apply the three patches included in dc390-20-kernel.diff
+(Applying them: cd /usr/src; patch -p0 <~/dc390-20-kernel.diff)
+The patches are against 2.1.103, so you might have to manually resolve
+rejections when applying to another kernel version.
+
+The patches will update the kernel startup code to allow boot parameters to
+be passed to the driver, update the Documentation and finally offer you the
+possibility to omit the non-DC390 parts of the driver.
+(By selecting "Omit support for non DC390" you basically disable the
+emulation of a DC390 EEPROM for non DC390 adapters. This saves a few bytes
+of memory.)
+
+If you got a very old kernel without the tmscsim driver (pre 2.0.31)
+I recommend upgrading your kernel. However, if you don't want to, please
+contact me to get the appropriate patches.
+
+Testing a SCSI driver is always a delicate thing to do. The 2.0 driver has
+proven stable on many systems, but it's still a good idea to take some
+precautions. In an ideal world you would have a full backup of your disks.
+The world isn't ideal and most people don't have full backups (me neither).
+So take at least the following two measures:
+* make your kernel remount the FS read-only on detecting an error:
+  tune2fs -e remount-ro /dev/sd??
+* have copies of your SCSI disk's partition tables on some safe location:
+  dd if=/dev/sda of=/mnt/floppy/sda bs=512 count=1
+* make sure you are able to boot Linux (e.g. from floppy disk using InitRD)
+  if your SCSI disk gets corrupted. You can use 
+  ftp://student.physik.uni-dortmund.de/pub/linux/kernel/bootdisk.gz
+
+One more warning: I used to overclock my PCI bus to 41.67 MHz. My Tekram
+DC390F (Sym53c875) accepted this as well as my Millenium. But the Am53C974
+produced errors and started to corrupt my disks. So don't do that! A 37.50
+MHz PCI bus works for me, though, but I don't recommend using higher clocks
+than the 33.33 MHz being in the PCI spec.
+
+If you want to share the IRQ with another device and the driver refuses to
+do, you might succeed with changing the DC390_IRQ type in tmscsim.c to 
+SA_SHIRQ | SA_INTERRUPT.
+
+
+3.Features
+----------
+- SCSI
+ * Tagged queueing
+ * Sync speed up to 10 MHz
+ * Disconnection
+ * Multiple LUNs
+
+- General / Linux interface
+ * Support for up to 4 adapters.
+ * DC390 EEPROM usage or boot/module params
+ * Information via cat /proc/scsi/tmscsim/?
+ * Dynamically configurable by writing to /proc/scsi/tmscsim/?
+ * Dynamic allocation of resources
+ * SMP support: Adapter specific locks (Linux 2.1.x)
+ * Uniform source code for Linux-2.x.y
+ * Support for dyn. addition/removal of devices via add/remove-single-device
+   (Try: echo "scsi add-single-device H C I L" >/proc/scsi/scsi 
+    H = Host, C = Channel, I = SCSI ID, L = SCSI LUN.) Use with care!
+ * Try to use the partition table for the determination of the mapping
+
+
+4. Configuration via /proc/scsi/tmscsim/?
+-----------------------------------------
+First of all look at the output of /proc/scsi/tmscsim/? by typing
+ cat /proc/scsi/tmscsim/?
+The "?" should be replaced by the SCSI host number. (The shell might do this
+for you.)
+You will see some info regarding the adapter and, at the end, a listing of
+the attached devices and their settings.
+
+Here's an example:
+garloff@kg1:/home/garloff > cat /proc/scsi/tmscsim/0
+Tekram DC390/AM53C974 PCI SCSI Host Adapter, Driver Version 1.20s, 1998/08/20
+SCSI Host Nr 0, AM53C974 Adapter Nr 0
+IOPortBase 0x6200, IRQLevel 0x09
+MaxID 7, MaxLUN 8, AdapterID 7, SelTimeout 250 ms
+TagMaxNum 16, Status 0, ACBFlag 0, GlitchEater 24 ns
+Statistics: Nr of Cmnds 39563, Cmnds not sent directly 0, Out of SRB conds 0
+            Nr of lost arbitrations 17
+Nr of attached devices: 4, Nr of DCBs: 4
+Idx ID LUN Prty Sync DsCn SndS TagQ STOP NegoPeriod SyncSpeed SyncOffs
+00  00  00  Yes  Yes  Yes  Yes  Yes  No    100 ns    10.0 M      15
+01  01  00  Yes  Yes  Yes  Yes  Yes  No    100 ns    10.0 M      15
+02  03  00  Yes  Yes  Yes  Yes  No   No    100 ns    10.0 M      15
+03  05  00  Yes  No   Yes  Yes  No   No   (200 ns)
+
+Note that the settings MaxID and MaxLUN are not zero- but one-based, which
+means that a setting MaxLUN=4, will result in the support of LUNs 0..3. This
+is somehow inconvenient, but the way the mid-level SCSI code expects it to be.
+
+ACB and DCB are acronyms for Adapter Control Block and Device Control Block.
+These are data structures of the driver containing information about the
+adapter and the connected SCSI devices respectively.
+
+Idx is the device index (just a consecutive number for the driver), ID and
+LUN are the SCSI ID and LUN, Prty means Parity checking, Sync synchronous
+negotiation, DsCn Disconnection, SndS Send Start command on startup (not
+used by the driver) and TagQ Tagged Command Queueing. NegoPeriod and
+SyncSpeed are somehow redundant, because they are reciprocal values 
+(1 / 112 ns = 8.9 MHz). At least in theory. The driver is able to adjust the
+NegoPeriod more accurate (4ns) than the SyncSpeed (1 / 25ns). I don't know
+if certain devices will have problems with this discrepancy. Max. speed is
+10 MHz corresp. to a min. NegoPeriod of 100 ns. 
+(The driver allows slightly higher speeds if the devices (Ultra SCSI) accept
+it, but that's out of adapter spec, on your own risk and unlikely to improve
+performance. You're likely to crash your disks.) 
+SyncOffs is the offset used for synchronous negotiations; max. is 15. 
+The last values are only shown, if Sync is enabled. (NegoPeriod is still
+displayed in brackets to show the values which will be used after enabling
+Sync.)
+The STOP parameter is for testing/debugging purposes only and should bet set
+to No. Please don't fiddle with it, unless you want to get rid of the
+contents of your disk.
+
+If you want to change a setting, you can do that by writing to
+/proc/scsi/tmscsim/?. Basically you have to imitate the output of driver.
+(Don't use the brackets for NegoPeriod on Sync disabled devices.)
+You don't have to care about capitalisation. The driver will accept space,
+tab, comma, = and : as separators.
+
+There are three kinds of changes: 
+
+(1) Change driver settings: 
+    You type the names of the parameters and the params following it.
+    Example:
+     echo "MaxLUN=8 seltimeout 200" >/proc/scsi/tmscsim/0
+
+    Note that you can only change MaxID, MaxLUN, AdapterID, SelTimeOut,
+    TagMaxNum, ACBFlag and GlitchEater. Don't change ACBFlag unless you
+    want to see what happens, if the driver hangs.
+
+(2) Change device settings: You write a config line to the driver. The Nr
+    must match the ID and LUN given. If you give "-" as parameter, it is
+    ignored and the corresponding setting won't be changed. 
+    You can use "y" or "n" instead of "Yes" and "No" if you want to.
+    You don't need to specify a full line. The driver automatically performs
+    an INQUIRY on the device if necessary to check if it is capable to operate
+    with the given settings (Sync, TagQ).
+    Examples:
+     echo "0 0 0 y y y - y - 10" >/proc/scsi/tmscsim/0
+     echo "3 5 0 y n y" >/proc/scsi/tmscsim/0
+
+    To give a short explanation of the first example: 
+    The first three numbers, "0 0 0" (Device index 0, SCSI ID 0, SCSI LUN 0),
+    select the device to which the following parameters apply. Note that it
+    would be sufficient to use the index or both SCSI ID and LUN, but I chose
+    to require all three to have a syntax similar to the output.
+    The following "y y y - y" enables Parity checking, enables Synchronous
+    transfers, Disconnection, leaves Send Start (not used) untouched and
+    enables Tagged Command Queueing for the selected device. The "-" skips
+    the Negotiation Period setting but the "10" sets the max sync. speed to
+    10 MHz. It's useless to specify both NegoPeriod and SyncSpeed as
+    discussed above. The values used in this example will result in maximum
+    performance.
+
+(3) Special commands: You can force a SCSI bus reset, an INQUIRY command and
+    the removal of a device's DCB.
+    This is only used for debugging when you meet problems. The parameter of
+    the INQUIRY and remove command is the device index as shown by the
+    output of /proc/scsi/tmscsim/? in the device listing in the first column
+    (Idx).
+    Examples:
+     echo "reset" >/proc/scsi/tmscsim/0
+     echo "inquiry 1" >/proc/scsi/tmscsim/0
+     echo "remove 2" >/proc/scsi/tmscsim/1
+
+    Note that you will meet problems when you remove a device's DCB with the
+    remove command if it contains partitions which are mounted. Only use it
+    after unmounting its partitions, telling the SCSI mid-level code to
+    remove it (scsi remove-single-device) and you really need a few bytes of
+    memory.
+
+
+I'd suggest reviewing the output of /proc/scsi/tmscsim/? after changing
+settings to see if everything changed as requested.
+
+
+5. Configuration via boot/module parameters
+-------------------------------------------
+With the DC390, the driver reads its EEPROM settings and IGNORES boot / 
+module parameters. If you want to override the EEPROM settings of a DC390, 
+you have to use the /proc/scsi/tmscsim/? interface described in the above
+chapter.
+
+However, if you do have another AM53C974 based adapter you might want to
+adjust some settings before you are able to write to the /proc/scsi/tmscsim/?
+pseudo-file, e.g. if you want to use another adapter ID than 7. (Note that
+the log message "DC390: No EEPROM found!" is normal without a DC390.)
+For this purpose, you can pass options to the driver before it is initialised
+by using kernel or module parameters. See lilo(8) or modprobe(1) manual
+pages on how to pass params to the kernel or a module.
+
+The syntax of the params is much shorter than the syntax of the /proc/...
+interface. This makes it a little bit more difficult to use. However, long
+parameter lines have the risk to be misinterpreted and the length of kernel
+parameters is limited.
+
+As the support for non-DC390 adapters works by simulating the values of the
+DC390 EEPROM, the settings are given in a DC390 BIOS' way.
+
+Here's the syntax:
+tmscsim=AdaptID,SpdIdx,DevMode,AdaptMode,TaggedCmnds
+
+Each of the parameters is a number, containing the described information:
+
+* AdaptID: The SCSI ID of the host adapter. Must be in the range 0..7
+  Default is 7.
+
+* SpdIdx: The index of the maximum speed as in the DC390 BIOS. The values
+  0..7 mean 10, 8.0, 6.7, 5.7, 5.0, 4.0, 3.1 and 2 MHz resp. Default is
+  1 (8.0 MHz).
+
+* DevMode is a bit mapped value describing the per-device features. It
+  applies to all devices. (Sync, Disc and TagQ will only apply, if the
+  device supports it.) The meaning of the bits (* = default):
+
+   Bit Val(hex) Val(dec)  Meaning
+   *0	 0x01	    1	  Parity check
+   *1	 0x02	    2	  Synchronous Negotiation
+   *2	 0x04	    4	  Disconnection
+   *3	 0x08	    8	  Send Start command on startup. (Not used)
+   *4	 0x10	   16	  Tagged Queueing
+
+  As usual, the desired value is obtained by adding the wanted values. If
+  you want to enable all values, e.g., you would use 31(0x1f). Default is 31.
+
+* AdaptMode is a bit mapped value describing the enabled adapter features.
+
+   Bit Val(hex) Val(dec)  Meaning
+   *0	 0x01	    1	  Support more than two drives. (Not used)
+   *1	 0x02	    2	  Use DOS compatible mapping for HDs greater than 1GB.
+   *2	 0x04	    4	  Reset SCSI Bus on startup.
+   *3	 0x08	    8	  Active Negation: Improves SCSI Bus noise immunity.
+    4	 0x10	   16	  Immediate return on BIOS seek command. (Not used)
+ (*)5	 0x20	   32	  Check for LUNs >= 1.
+  
+  The default for LUN Check depends on CONFIG_SCSI_MULTI_LUN.
+
+* TaggedCmnds is a number indicating the maximum number of Tagged Commands.
+  It is the binary logarithm - 1 of the actual number. Max is 4 (32).
+   Value  Number of Tagged Commands
+     0		 2
+     1		 4
+     2		 8
+    *3		16
+     4		32
+
+Example:
+ modprobe tmscsim tmscsim=6,2,31
+would set the adapter ID to 6, max. speed to 6.7 MHz, enable all device
+features and leave the adapter features and the number of Tagged Commands 
+to the defaults.
+
+As you can see, you don't need to specify all of the five params.
+
+The defaults (7,1,31,15,3) are aggressive to allow good performance. You can
+use tmscsim=7,0,31,63,4 for maximum performance, if your SCSI chain is
+perfect. If you meet problems, you can use tmscsim=-1 which is a shortcut
+for tmscsim=7,4,9,15,2. 
+
+
+6. Potential improvements
+-------------------------
+Most of the intended work on the driver has been done. Here are a few ideas
+to further improve its usability:
+
+* More intelligent abort() routine
+* Implement new_eh code (Linux-2.1+)
+* Have the mid-level code (and not the driver) handle more of the various
+  conditions.
+* Rework command queueing in the driver
+* More user friendly boot/module param syntax
+
+Further investigation on these problems:
+
+* TagQ and Disconnection (Resel: SRB Tag Seleection)
+* Problems with IRQ sharing (IO-APIC on SMP Systems) (??)
+* Driver crashes with readcdda (xcdroast)
+
+Known problems:
+
+* There was a report that with a certain Scanner, the last SCSI command
+  won't be finished correctly. This might be a command queueing bug or a bug
+  in SCSI implementation of the scanner. Issueing another command to the
+  scanner seems to help. (Try echo "INQUIRY x" >/proc/scsi/tmscsim/?, where
+  x is the index (not the SCSI ID!) of the scanner. See 4.(3).)
+* If there is a valid partition table, the driver will use it for determing
+  the mapping. Other operating systems may not like this mapping, though
+  it's consistent with the BIOS' behaviour. Old DC390 drivers ignored the
+  partition table and used a H/S = 64/32 or 255/63 translation. So if you
+  want to be compatible to those, use this old mapping when creating
+  partition tables.
+* In some situations, the driver will get stuck in an abort loop. Please
+  disable DsCn, if you meet this problem. Please contact me for further
+  debugging.
+* 2.1.115+: Linux misses locks in sr_ioctl.c and scsi_ioctl.c
+  There used to be a patch included here, which partially solved the
+  problem. I suggest you contact Chiaki Ishikawa <ishikawa@yk.rim.or.jp>, 
+  Richard Waltham <dormouse@farsrobt.demon.co.uk> or Doug Ledford
+  <dledford@dialnet.net>, if you want to help further debugging it.
+* 2.0.35: CD changers (e.g. NAKAMICHI MBR-7.{0,2}) have problems because
+  the mid-level code doesn't handle BLIST_SINGLELUN correctly. Apply
+  the patch 2035-scsi-singlelun.diff. Thanks to Chiaki Ishikawa.
+  I was told that this fix will be in 2.0.36, so you don't need it for
+  2.0.36. 
+[The patch file is contained in the dc390-XXX.tar.gz files which can be found
+on the ftp server. See below.]
+
+
+7. Bug reports, debugging and updates
+-------------------------------------
+Whenever you have problems with the driver, you are invited to ask the
+author for help. However, I'd suggest reading the docs and trying to solve
+the problem yourself, first. 
+If you find something, which you believe to be a bug, please report it to me. 
+Please append the output of /proc/scsi/scsi, /proc/scsi/tmscsim/? and
+maybe the DC390 log messages to the report. 
+
+Bug reports should be send to me (Kurt Garloff <K.Garloff@ping.de>) as well
+as to the linux-scsi list (<linux-scsi@vger.rutgers.edu>), as sometimes bugs
+are caused by the SCSI mid-level code.
+
+I will ask you for some more details and probably I will also ask you to
+enable some of the DEBUG options in the driver (tmscsim.c:DC390_DEBUGXXX
+defines). The driver will produce some data for the syslog facility then.
+Beware: If your syslog gets written to a SCSI disk connected to your
+AM53C974, the logging might produce log output again, and you might end
+having your box spending most of its time doing the logging.
+
+The latest version of the driver can be found at:
+ftp://student.physik.uni-dortmund.de/pub/linux/kernel/dc390/
+
+
+8. Acknowledgements
+-------------------
+Thanks to Linus Torvalds, Alan Cox, David Miller, Rik v. Riel, the FSF
+people, the XFree86 team and all the others for the wonderful OS and
+software. 
+Thanks to C.L. Huang and Philip Giang (Tekram) for the initial driver
+release and support.
+Thanks to Doug Ledford, Gerard Roudier for support with SCSI coding.
+Thanks to a lot of people (espec. Chiaki Ishikawa, Andreas Haumer, Hubert 
+Tonneau) for intensively testing the driver (and even risking data loss
+doing this during early revisions). 
+
+
+-------------------------------------------------------------------------
+Written by Kurt Garloff <K.Garloff@ping.de> 1998/06/11
+Last updated 1998/10/15, driver revision 2.0b
+$Id: README.tmscsim,v 2.4 1998/10/24 08:45:02 garloff Exp $
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