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List:       linux-kernel
Subject:    [patches] Slow PS/2-floppies and ESDI
From:       David Weinehall <tao () acc ! umu ! se>
Date:       1998-09-30 22:49:15
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These two *small* patches (compiling cleanly into v2.1.122, but should
work equally well on v2.1.123), touches only one file each, and does the
following:

The first patch modifies **floppy.c** by adding a flag "slow"
that slows the step-rate down to 1/4 of the normal; some models of the IBM
PS/2 has a buggy floppy that doesn't work without this patch.

The second patch modifies **main.c** by removing the NO-NO! "ed=" entry
and adding the needed "edb=" entry.

Any comments are welcome.

/David Weinehall

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--- linux-2.1.122/drivers/block/floppy.c	Sun Sep 13 21:12:34 1998
+++ linux-2.1.122mca/drivers/block/floppy.c	Thu Oct  1 00:14:43 1998
@@ -102,6 +102,10 @@
  * failures.
  */
 
+/*
+ * 1998/09/20 -- David Weinehall -- Added slow-down code for buggy PS/2-drives.
+ */
+
 #define FLOPPY_SANITY_CHECK
 #undef  FLOPPY_SILENT_DCL_CLEAR
 
@@ -149,6 +153,10 @@
 #include <linux/interrupt.h>
 #include <linux/init.h>
 
+#ifdef CONFIG_MCA
+static int slow_floppy = 0;
+#endif
+
 #include <asm/dma.h>
 #include <asm/irq.h>
 #include <asm/system.h>
@@ -1300,6 +1308,11 @@
 
 	/* Convert step rate from microseconds to milliseconds and 4 bits */
 	srt = 16 - (DP->srt*scale_dtr/1000 + NOMINAL_DTR - 1)/NOMINAL_DTR;
+#ifdef CONFIG_MCA
+	if( slow_floppy ) {
+		srt = srt / 4;
+	}
+#endif
 	SUPBOUND(srt, 0xf);
 	INFBOUND(srt, 0);
 
@@ -4026,7 +4039,18 @@
 {
 	int i;
 	int param;
-	if (str)
+	if (str) {
+#ifdef CONFIG_MCA
+	/*
+	 * PS/2 floppies have much slower step rates than regular floppies.
+	 * It's been recommended that take about 1/4 of the default speed
+	 * in some more extreme cases.
+	*/
+	if( strcmp(str,"slow") == 0) {
+		slow_floppy = 1;
+		return;
+	}
+#endif 
 		for (i=0; i< ARRAY_SIZE(config_params); i++){
 			if (strcmp(str,config_params[i].name) == 0){
 				if (ints[0])
@@ -4044,6 +4068,7 @@
 				return;
 			}
 		}
+	}
 	if (str) {
 		DPRINT("unknown floppy option [%s]\n", str);
 		

-----

--- linux-2.1.122/init/main.c	Wed Sep 16 22:25:57 1998
+++ linux-2.1.122mca/init/main.c	Wed Sep 30 11:52:26 1998
@@ -455,6 +456,7 @@
 #endif
 #ifdef CONFIG_BLK_DEV_PS2
 	{ "eda",     0x2400 },
+	{ "edb",     0x2440 },
 #endif
 #ifdef CONFIG_PARIDE_PD
 	{ "pda",	0x2d00 },
@@ -663,7 +668,8 @@
 	{ "floppy=", floppy_setup },
 #endif
 #ifdef CONFIG_BLK_DEV_PS2
-	{ "ed=", ed_setup },
+	{ "eda=", ed_setup },
+	{ "edb=", ed_setup },
 	{ "tp720=", tp720_setup },
 #endif
 #ifdef CONFIG_CDU31A


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