linux-kernel

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-Id: <200802172108.JRY53937@mr08.lnh.mail.rcn.net>
Date:	Sun, 17 Feb 2008 16:08:20 -0500 (EST)
From:	<dpreed@...d.com>
To:	unlisted-recipients:; (no To-header on input)

>From David P. Reed <dpreed@...d.com> Sat Feb 16 15:05:17 2008
Message-Id: <20080216200517.467388261@...d.com>>
References: <20080216200517.113862251@...d.com>>
User-Agent: quilt/0.46-1
Date: Sat, 16 Feb 2008 15:05:20 -0500
From: David P. Reed <dpreed@...d.com>
To: Thomas Gleixner <tglx@...utronix.de>,
 Ingo Molnar <mingo@...hat.com>,
 "H. Peter Anvin" <hpa@...or.com>
Cc: linux-kernel@...r.kernel.org,
 "David P. Reed" <dpreed@...d.com>
Subject: [PATCH 3/3] x86: fix pcspkr to not use inb_p/outb_p calls.
Content-Disposition: inline; filename=fix-pcspkr-iodelay.patch

Fix pcspkr driver to use explicit timing delay for access to PIT,
rather than inb_p/outb_p calls, which use insufficiently explicit
delays (defaulting to port 80 writes) that can cause freeze problems
on some machines, such as Quanta moterboard  machines using ENE EC's.
The explicit timing delay is only needed for accesses to the 8253 PIT.
The standard requirement for the 8253 to respond to successive writes
is 1 microsecond.  The 8253 has never been on the expansion bus, so 
a proper delay has nothing to do with expansion bus timing, but instead
its internal logic's capability to react to input.  Since udelay is correctly
calibrated by the time the pcspkr driver is initialized, we use 1 microsecond
as the timing.

Also shorten lines to less than 80 characters.

Signed-off-by: David P. Reed <dpreed@...d.com>

Index: linux-2.6/drivers/input/misc/pcspkr.c
===================================================================
--- linux-2.6.orig/drivers/input/misc/pcspkr.c
+++ linux-2.6/drivers/input/misc/pcspkr.c
@@ -32,9 +32,11 @@ MODULE_ALIAS("platform:pcspkr");
 static DEFINE_SPINLOCK(i8253_lock);
 #endif
 
-static int pcspkr_event(struct input_dev *dev, unsigned int type, unsigned int code, int value)
+static int pcspkr_event(struct input_dev *dev, unsigned int type,
+			unsigned int code, int value)
 {
 	unsigned int count = 0;
+	unsigned char mask;
 	unsigned long flags;
 
 	if (type != EV_SND)
@@ -51,17 +53,21 @@ static int pcspkr_event(struct input_dev
 
 	spin_lock_irqsave(&i8253_lock, flags);
 
+	mask = inb(0x61);
 	if (count) {
 		/* enable counter 2 */
-		outb_p(inb_p(0x61) | 3, 0x61);
+		outb(mask | 3, 0x61);
+		/* some 8253's may require 1 usec. between accesses */
 		/* set command for counter 2, 2 byte write */
-		outb_p(0xB6, 0x43);
+		outb(0xB6, 0x43);
+		udelay(1);
 		/* select desired HZ */
-		outb_p(count & 0xff, 0x42);
+		outb(count & 0xff, 0x42);
+		udelay(1);
 		outb((count >> 8) & 0xff, 0x42);
 	} else {
 		/* disable counter 2 */
-		outb(inb_p(0x61) & 0xFC, 0x61);
+		outb(mask & 0xFC, 0x61);
 	}
 
 	spin_unlock_irqrestore(&i8253_lock, flags);

-- 
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/