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Message-ID: <4A368600.5030009@LiPPERTEmbedded.de>
Date: Mon, 15 Jun 2009 19:33:52 +0200
From: Jens Rottmann <JRottmann@...PERTEmbedded.de>
To: linux-parport@...ts.infradead.org
CC: linux-kernel@...r.kernel.org
Subject: [PATCH] parport_pc: after superio probing restore original register
values
CONFIG_PARPORT_PC_SUPERIO probes for various superio chips by writing
byte sequences to a set of different potential I/O ranges. But the
probed ranges are not exclusive to parallel ports. Some of our boards
just happen to have a watchdog in one of them. Took us almost a week
to figure out why some distros reboot without warning after running
flawlessly for 3 hours. For exactly 170 = 0xAA minutes, that is ...
Fixed by restoring original values after probing. Also fixed too small
request_region() in detect_and_report_it87().
Signed-off-by: Jens Rottmann <JRottmann@...PERTEmbedded.de>
---
Patch is against Linus' current git tree.
--- linux-2.6.30-git8/drivers/parport/parport_pc.c
+++ conservative-superio-probing/drivers/parport/parport_pc.c
@@ -1471,11 +1471,13 @@ static void __devinit decode_smsc(int ef
static void __devinit winbond_check(int io, int key)
{
- int devid, devrev, oldid, x_devid, x_devrev, x_oldid;
+ int origval, devid, devrev, oldid, x_devid, x_devrev, x_oldid;
if (!request_region(io, 3, __func__))
return;
+ origval = inb(io); /* Save original value */
+
/* First probe without key */
outb(0x20, io);
x_devid = inb(io + 1);
@@ -1495,6 +1497,8 @@ static void __devinit winbond_check(int
oldid = inb(io + 1);
outb(0xaa, io); /* Magic Seal */
+ outb(origval, io); /* in case we poked some entirely different hardware */
+
if ((x_devid == devid) && (x_devrev == devrev) && (x_oldid == oldid))
goto out; /* protection against false positives */
@@ -1505,11 +1509,15 @@ out:
static void __devinit winbond_check2(int io, int key)
{
- int devid, devrev, oldid, x_devid, x_devrev, x_oldid;
+ int origval[3], devid, devrev, oldid, x_devid, x_devrev, x_oldid;
if (!request_region(io, 3, __func__))
return;
+ origval[0] = inb(io); /* Save original values */
+ origval[1] = inb(io + 1);
+ origval[2] = inb(io + 2);
+
/* First probe without the key */
outb(0x20, io + 2);
x_devid = inb(io + 2);
@@ -1528,6 +1536,10 @@ static void __devinit winbond_check2(int
oldid = inb(io + 2);
outb(0xaa, io); /* Magic Seal */
+ outb(origval[0], io); /* in case we poked some entirely different hardware */
+ outb(origval[1], io + 1);
+ outb(origval[2], io + 2);
+
if (x_devid == devid && x_devrev == devrev && x_oldid == oldid)
goto out; /* protection against false positives */
@@ -1538,11 +1550,13 @@ out:
static void __devinit smsc_check(int io, int key)
{
- int id, rev, oldid, oldrev, x_id, x_rev, x_oldid, x_oldrev;
+ int origval, id, rev, oldid, oldrev, x_id, x_rev, x_oldid, x_oldrev;
if (!request_region(io, 3, __func__))
return;
+ origval = inb(io); /* Save original value */
+
/* First probe without the key */
outb(0x0d, io);
x_oldid = inb(io + 1);
@@ -1566,6 +1580,8 @@ static void __devinit smsc_check(int io,
rev = inb(io + 1);
outb(0xaa, io); /* Magic Seal */
+ outb(origval, io); /* in case we poked some entirely different hardware */
+
if (x_id == id && x_oldrev == oldrev &&
x_oldid == oldid && x_rev == rev)
goto out; /* protection against false positives */
@@ -1602,11 +1618,12 @@ static void __devinit detect_and_report_
static void __devinit detect_and_report_it87(void)
{
u16 dev;
- u8 r;
+ u8 origval, r;
if (verbose_probing)
printk(KERN_DEBUG "IT8705 Super-IO detection, now testing port 2E ...\n");
- if (!request_region(0x2e, 1, __func__))
+ if (!request_region(0x2e, 2, __func__))
return;
+ origval = inb(0x2e); /* Save original value */
outb(0x87, 0x2e);
outb(0x01, 0x2e);
outb(0x55, 0x2e);
@@ -1626,8 +1643,10 @@ static void __devinit detect_and_report_
outb(r | 8, 0x2F);
outb(0x02, 0x2E); /* Lock */
outb(0x02, 0x2F);
+ } else {
+ outb(origval, 0x2e); /* Oops, sorry to disturb */
}
- release_region(0x2e, 1);
+ release_region(0x2e, 2);
}
#endif /* CONFIG_PARPORT_PC_SUPERIO */
_
--
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