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Message-ID: <20071217105744.GA14315@elte.hu>
Date: Mon, 17 Dec 2007 11:57:44 +0100
From: Ingo Molnar <mingo@...e.hu>
To: Rene Herman <rene.herman@...il.com>
Cc: "H. Peter Anvin" <hpa@...or.com>, Paul Rolland <rol@...917.net>,
Alan Cox <alan@...rguk.ukuu.org.uk>,
Pavel Machek <pavel@....cz>, "David P. Reed" <dpreed@...d.com>,
Thomas Gleixner <tglx@...utronix.de>,
linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
rol@...be.net
Subject: Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override.
* Rene Herman <rene.herman@...il.com> wrote:
> On 16-12-07 16:22, Ingo Molnar wrote:
>
>> looks good to me. Could you please also provide three more controls that i
>> suggested earlier:
>>
>> - a boot option enabling/disabling the udelay based code
>> - a .config method of enabling/disabling the udelay based code
>> - a sysctl to toggle it
>>
>> if we want to clean this all up we'll need as many controls as possible.
>
> This version does the boot and the .config option but not the sysctl.
> It makes for clumsy code and I don't believe it provides for much
> added value as soon as you have the boot option. I am moreover not
> completely confident about things such as paravirt liking the
> possibility of the native_io_delay being changed out from under them
> at unpredictable times.
>
> So how is this? Also fixes a few problems with the previous version.
thanks Rene! I've added your patch to x86.git. I changed a few things
ontop of it, see the additional changelog and delta patch below.
Ingo
------------>
- add the io_delay=none method
- make each method selectable from the kernel config
- simplify the delay code a bit by getting rid of an indirect function call
- add the /proc/sys/kernel/io_delay_type sysctl
- change 'standard' and 'alternate' to 0x80 and 0xed
- make the io delay config not depend on CONFIG_DEBUG_KERNEL
---
Documentation/kernel-parameters.txt | 12 ++--
arch/x86/Kconfig.debug | 79 +++++++++++++++++++++++++--
arch/x86/kernel/io_delay.c | 103 ++++++++++++++++--------------------
include/asm-x86/io_32.h | 2
include/asm-x86/io_64.h | 2
kernel/sysctl.c | 9 +++
6 files changed, 138 insertions(+), 69 deletions(-)
Index: linux-x86.q/Documentation/kernel-parameters.txt
===================================================================
--- linux-x86.q.orig/Documentation/kernel-parameters.txt
+++ linux-x86.q/Documentation/kernel-parameters.txt
@@ -786,12 +786,14 @@ and is between 256 and 4096 characters.
then look in the higher range.
io_delay= [X86-32,X86-64] I/O delay method
- standard
- Standard port 0x80 delay
- alternate
- Alternate port 0xed delay
+ 0x80
+ Standard port 0x80 based delay
+ 0xed
+ Alternate port 0xed based delay (needed on some systems)
udelay
- Simple two microsecond delay
+ Simple two microseconds delay
+ none
+ No delay
io7= [HW] IO7 for Marvel based alpha systems
See comment before marvel_specify_io7 in
Index: linux-x86.q/arch/x86/Kconfig.debug
===================================================================
--- linux-x86.q.orig/arch/x86/Kconfig.debug
+++ linux-x86.q/arch/x86/Kconfig.debug
@@ -112,13 +112,78 @@ config IOMMU_LEAK
Add a simple leak tracer to the IOMMU code. This is useful when you
are debugging a buggy device driver that leaks IOMMU mappings.
-config UDELAY_IO_DELAY
- bool "Delay I/O through udelay instead of outb"
- depends on DEBUG_KERNEL
+#
+# IO delay types:
+#
+
+config IO_DELAY_TYPE_0X80
+ int
+ default "0"
+
+config IO_DELAY_TYPE_0XED
+ int
+ default "1"
+
+config IO_DELAY_TYPE_UDELAY
+ int
+ default "2"
+
+config IO_DELAY_TYPE_NONE
+ int
+ default "3"
+
+choice
+ prompt "IO delay type"
+ default IO_DELAY_0X80
+
+config IO_DELAY_0X80
+ bool "port 0x80 based port-IO delay [recommended]"
+ help
+ This is the traditional Linux IO delay used for in/out_p.
+ It is the most tested hence safest selection here.
+
+config IO_DELAY_0XED
+ bool "port 0xed based port-IO delay"
help
- Make inb_p/outb_p use udelay() based delays by default. Please note
- that udelay() does not have the same bus-level side-effects that
- the normal outb based delay does meaning this could cause drivers
- to change behaviour and/or bugs to surface.
+ Use port 0xed as the IO delay. This frees up port 0x80 which is
+ often used as a hardware-debug port.
+
+config IO_DELAY_UDELAY
+ bool "udelay based port-IO delay"
+ help
+ Use udelay(2) as the IO delay method. This provides the delay
+ while not having any side-effect on the IO port space.
+
+config IO_DELAY_NONE
+ bool "no port-IO delay"
+ help
+ No port-IO delay. Will break on old boxes that require port-IO
+ delay for certain operations. Should work on most new machines.
+
+endchoice
+
+if IO_DELAY_0X80
+config DEFAULT_IO_DELAY_TYPE
+ int
+ default IO_DELAY_TYPE_0X80
+endif
+
+if IO_DELAY_0XED
+config DEFAULT_IO_DELAY_TYPE
+ int
+ default IO_DELAY_TYPE_0XED
+endif
+
+if IO_DELAY_UDELAY
+config DEFAULT_IO_DELAY_TYPE
+ int
+ default IO_DELAY_TYPE_UDELAY
+endif
+
+if IO_DELAY_NONE
+config DEFAULT_IO_DELAY_TYPE
+ int
+ default IO_DELAY_TYPE_NONE
+endif
endmenu
Index: linux-x86.q/arch/x86/kernel/io_delay.c
===================================================================
--- linux-x86.q.orig/arch/x86/kernel/io_delay.c
+++ linux-x86.q/arch/x86/kernel/io_delay.c
@@ -1,5 +1,9 @@
/*
* I/O delay strategies for inb_p/outb_p
+ *
+ * Allow for a DMI based override of port 0x80, needed for certain HP laptops
+ * and possibly other systems. Also allow for the gradual elimination of
+ * outb_p/inb_p API uses.
*/
#include <linux/kernel.h>
#include <linux/module.h>
@@ -8,98 +12,83 @@
#include <linux/dmi.h>
#include <asm/io.h>
-/*
- * Allow for a DMI based override of port 0x80 needed for certain HP laptops
- */
-#define IO_DELAY_PORT_STD 0x80
-#define IO_DELAY_PORT_ALT 0xed
-
-static void standard_io_delay(void)
-{
- asm volatile ("outb %%al, %0" : : "N" (IO_DELAY_PORT_STD));
-}
-
-static void alternate_io_delay(void)
-{
- asm volatile ("outb %%al, %0" : : "N" (IO_DELAY_PORT_ALT));
-}
-
-/*
- * 2 usecs is an upper-bound for the outb delay but note that udelay doesn't
- * have the bus-level side-effects that outb does
- */
-#define IO_DELAY_USECS 2
+int io_delay_type __read_mostly = CONFIG_DEFAULT_IO_DELAY_TYPE;
+EXPORT_SYMBOL_GPL(io_delay_type);
-/*
- * High on a hill was a lonely goatherd
- */
-static void udelay_io_delay(void)
-{
- udelay(IO_DELAY_USECS);
-}
-
-#ifndef CONFIG_UDELAY_IO_DELAY
-static void (*io_delay)(void) = standard_io_delay;
-#else
-static void (*io_delay)(void) = udelay_io_delay;
-#endif
+static int __initdata io_delay_override;
/*
* Paravirt wants native_io_delay to be a constant.
*/
void native_io_delay(void)
{
- io_delay();
+ switch (io_delay_type) {
+ default:
+ case CONFIG_IO_DELAY_TYPE_0X80:
+ asm volatile ("outb %al, $0x80");
+ break;
+ case CONFIG_IO_DELAY_TYPE_0XED:
+ asm volatile ("outb %al, $0xed");
+ break;
+ case CONFIG_IO_DELAY_TYPE_UDELAY:
+ /*
+ * 2 usecs is an upper-bound for the outb delay but
+ * note that udelay doesn't have the bus-level
+ * side-effects that outb does, nor does udelay() have
+ * precise timings during very early bootup (the delays
+ * are shorter until calibrated):
+ */
+ udelay(2);
+ case CONFIG_IO_DELAY_TYPE_NONE:
+ break;
+ }
}
EXPORT_SYMBOL(native_io_delay);
-#ifndef CONFIG_UDELAY_IO_DELAY
-static int __init dmi_alternate_io_delay_port(const struct dmi_system_id *id)
+static int __init dmi_io_delay_0xed_port(const struct dmi_system_id *id)
{
- printk(KERN_NOTICE "%s: using alternate I/O delay port\n", id->ident);
- io_delay = alternate_io_delay;
+ printk(KERN_NOTICE "%s: using 0xed I/O delay port\n", id->ident);
+ io_delay_type = CONFIG_IO_DELAY_TYPE_0XED;
+
return 0;
}
-static struct dmi_system_id __initdata alternate_io_delay_port_dmi_table[] = {
+/*
+ * Quirk table for systems that misbehave (lock up, etc.) if port
+ * 0x80 is used:
+ */
+static struct dmi_system_id __initdata io_delay_0xed_port_dmi_table[] = {
{
- .callback = dmi_alternate_io_delay_port,
+ .callback = dmi_io_delay_0xed_port,
.ident = "HP Pavilion dv9000z",
.matches = {
DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
DMI_MATCH(DMI_BOARD_NAME, "30B9")
}
},
- {
- }
+ { }
};
-static int __initdata io_delay_override;
-
void __init io_delay_init(void)
{
if (!io_delay_override)
- dmi_check_system(alternate_io_delay_port_dmi_table);
+ dmi_check_system(io_delay_0xed_port_dmi_table);
}
-#endif
static int __init io_delay_param(char *s)
{
- if (!s)
- return -EINVAL;
-
- if (!strcmp(s, "standard"))
- io_delay = standard_io_delay;
- else if (!strcmp(s, "alternate"))
- io_delay = alternate_io_delay;
+ if (!strcmp(s, "0x80"))
+ io_delay_type = CONFIG_IO_DELAY_TYPE_0X80;
+ else if (!strcmp(s, "0xed"))
+ io_delay_type = CONFIG_IO_DELAY_TYPE_0XED;
else if (!strcmp(s, "udelay"))
- io_delay = udelay_io_delay;
+ io_delay_type = CONFIG_IO_DELAY_TYPE_UDELAY;
+ else if (!strcmp(s, "none"))
+ io_delay_type = CONFIG_IO_DELAY_TYPE_NONE;
else
return -EINVAL;
-#ifndef CONFIG_UDELAY_IO_DELAY
io_delay_override = 1;
-#endif
return 0;
}
Index: linux-x86.q/include/asm-x86/io_32.h
===================================================================
--- linux-x86.q.orig/include/asm-x86/io_32.h
+++ linux-x86.q/include/asm-x86/io_32.h
@@ -259,6 +259,8 @@ static inline void io_delay_init(void)
#endif
extern void native_io_delay(void);
+extern int io_delay_type;
+
#if defined(CONFIG_PARAVIRT)
#include <asm/paravirt.h>
#else
Index: linux-x86.q/include/asm-x86/io_64.h
===================================================================
--- linux-x86.q.orig/include/asm-x86/io_64.h
+++ linux-x86.q/include/asm-x86/io_64.h
@@ -44,6 +44,8 @@ static inline void io_delay_init(void)
#endif
extern void native_io_delay(void);
+extern int io_delay_type;
+
static inline void slow_down_io(void)
{
native_io_delay();
Index: linux-x86.q/kernel/sysctl.c
===================================================================
--- linux-x86.q.orig/kernel/sysctl.c
+++ linux-x86.q/kernel/sysctl.c
@@ -53,6 +53,7 @@
#ifdef CONFIG_X86
#include <asm/nmi.h>
#include <asm/stacktrace.h>
+#include <asm/io.h>
#endif
static int deprecated_sysctl_warning(struct __sysctl_args *args);
@@ -683,6 +684,14 @@ static struct ctl_table kern_table[] = {
.mode = 0644,
.proc_handler = &proc_dointvec,
},
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "io_delay_type",
+ .data = &io_delay_type,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
#endif
#if defined(CONFIG_MMU)
{
--
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