patch-2.0.11 linux/Documentation/ide.txt

• Lines: 84
• Date: Mon Aug 5 08:12:24 1996
• Orig file: v2.0.10/linux/Documentation/ide.txt
• Orig date: Tue Jul 23 11:33:32 1996

diff -u --recursive --new-file v2.0.10/linux/Documentation/ide.txt linux/Documentation/ide.txt
@@ -1,4 +1,4 @@
-ide.txt -- Information regarding the Enhanced IDE drive in Linux 2.0.x
+ide.txt -- Information regarding the Enhanced IDE drive in Linux 2.0.xx
 ===============================================================================
 Supported by:
 	Mark Lord    <mlord@pobox.com>		-- disks, interfaces, probing
@@ -37,8 +37,8 @@
 NEW!	- support for reliable operation of buggy CMD-640 interfaces
 		- PCI support is automatic when cmd640 support is configured
 		- for VLB, use kernel command line option:   ide0=cmd640_vlb
-		- this support also enables the secondary i/f on most cards
-		- experimental interface timing parameter support
+		- this support also enables the secondary i/f when needed
+		- interface PIO timing & prefetch parameter support
 NEW!	- experimental support for UMC 8672 interfaces
 NEW!	- support for secondary interface on the FGI/Holtek HT-6560B VLB i/f
 		- use kernel command line option:   ide0=ht6560
@@ -62,7 +62,7 @@
 		  and direct reads of audio data.
 NEW!	- experimental support for Promise DC4030VL caching interface card
 NEW!		- email thanks/problems to: peterd@pnd-pc.demon.co.uk
-NEW!	- the hdparm-2.7 package can be used to set PIO modes for some chipsets.
+NEW!	- the hdparm-3.1 package can be used to set PIO modes for some chipsets.
 
 For work in progress, see the comments in ide.c, ide-cd.c, and triton.c.
 
@@ -71,17 +71,28 @@
 Look for this support to be added to the kernel soon.
 
 
-***  IMPORTANT NOTICES (for kernel versions after 1.3.21)
+***  IMPORTANT NOTICES:  BUGGY IDE CHIPSETS CAN CORRUPT DATA!!
 ***  =================
 ***  PCI versions of the CMD640 and RZ1000 interfaces are now detected
 ***  automatically at startup when PCI BIOS support is configured.
-***  Linux disables the "pre-fetch" or "read-ahead" modes of these interfaces
+***
+***  Linux disables the "prefetch" ("readahead") mode of the RZ1000
 ***  to prevent data corruption possible due to hardware design flaws.
-***  Use of the "serialize" option is no longer necessary.
+***
+***  For the CMD640, linux disables "IRQ unmasking" (hdparm -u1) on any
+***  drive for which the "prefetch" mode of the CMD640 is turned on.
+***  If "prefetch" is disabled (hdparm -p8), then "IRQ unmasking" can be
+***  used again.
+***
+***  For the CMD640, linux disables "32bit I/O" (hdparm -c1) on any drive
+***  for which the "prefetch" mode of the CMD640 is turned off.
+***  If "prefetch" is enabled (hdparm -p9), then "32bit I/O" can be
+***  used again.
 ***
 ***  The CMD640 is also used on some Vesa Local Bus (VLB) cards, and is *NOT*
 ***  automatically detected by Linux.  For safe, reliable operation with such
 ***  interfaces, one *MUST* use the "ide0=cmd640_vlb" kernel option.
+***
 ***  Use of the "serialize" option is no longer necessary.
 
 This is the multiple IDE interface driver, as evolved from hd.c.
@@ -107,7 +118,7 @@
 Interfaces beyond the first two are not normally probed for, but may be
 specified using kernel "command line" options.  For example,
 
-	ide3=0x168,0x36e,10	/* ioports 0x168-0x16f,0x36e, irq 11 */
+	ide3=0x168,0x36e,10	/* ioports 0x168-0x16f,0x36e, irq 10 */
 
 Normally the irq number need not be specified, as ide.c will probe for it:
 
@@ -244,6 +255,16 @@
 				Not fully supported by all chipset types,
 				and quite likely to cause trouble with
 				older/odd IDE drives.
+
+ "idebus=xx"		: inform IDE driver of VESA/PCI bus speed in Mhz,
+				where "xx" is between 25 and 66 inclusive,
+				used when tuning chipset PIO modes.
+				For PCI bus, 25 is correct for a P75 system,
+				30 is correct for P90,P120,P180 systems,
+				and 33 is used for P100,P133,P166 systems.
+				If in doubt, use idebus=33 for PCI.
+				As for VLB, it is safest to not specify it.
+				Bigger values are safer than smaller ones.
 
  "idex=noprobe"		: do not attempt to access/use this interface
  "idex=base"		: probe for an interface at the addr specified,