Commit b02aae9c authored by Rene Herman's avatar Rene Herman Committed by Ingo Molnar
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x86: provide a DMI based port 0x80 I/O delay override.



x86: provide a DMI based port 0x80 I/O delay override.

Certain (HP) laptops experience trouble from our port 0x80 I/O delay
writes. This patch provides for a DMI based switch to the "alternate
diagnostic port" 0xed (as used by some BIOSes as well) for these.

David P. Reed confirmed that port 0xed works for him and provides a
proper delay. The symptoms of _not_ working are a hanging machine,
with "hwclock" use being a direct trigger.

Earlier versions of this attempted to simply use udelay(2), with the
2 being a value tested to be a nicely conservative upper-bound with
help from many on the linux-kernel mailinglist but that approach has
two problems.

First, pre-loops_per_jiffy calibration (which is post PIT init while
some implementations of the PIT are actually one of the historically
problematic devices that need the delay) udelay() isn't particularly
well-defined. We could initialise loops_per_jiffy conservatively (and
based on CPU family so as to not unduly delay old machines) which
would sort of work, but...

Second, delaying isn't the only effect that a write to port 0x80 has.
It's also a PCI posting barrier which some devices may be explicitly
or implicitly relying on. Alan Cox did a survey and found evidence
that additionally some drivers may be racy on SMP without the bus
locking outb.

Switching to an inb() makes the timing too unpredictable and as such,
this DMI based switch should be the safest approach for now. Any more
invasive changes should get more rigid testing first. It's moreover
only very few machines with the problem and a DMI based hack seems
to fit that situation.

This also introduces a command-line parameter "io_delay" to override
the DMI based choice again:

	io_delay=<standard|alternate>

where "standard" means using the standard port 0x80 and "alternate"
port 0xed.

This retains the udelay method as a config (CONFIG_UDELAY_IO_DELAY) and
command-line ("io_delay=udelay") choice for testing purposes as well.

This does not change the io_delay() in the boot code which is using
the same port 0x80 I/O delay but those do not appear to be a problem
as David P. Reed reported the problem was already gone after using the
udelay version. He moreover reported that booting with "acpi=off" also
fixed things and seeing as how ACPI isn't touched until after this DMI
based I/O port switch I believe it's safe to leave the ones in the boot
code be.

The DMI strings from David's HP Pavilion dv9000z are in there already
and we need to get/verify the DMI info from other machines with the
problem, notably the HP Pavilion dv6000z.

This patch is partly based on earlier patches from Pavel Machek and
David P. Reed.
Signed-off-by: default avatarRene Herman <rene.herman@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 4c6b8b4d
......@@ -794,6 +794,14 @@ and is between 256 and 4096 characters. It is defined in the file
for translation below 32 bit and if not available
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
udelay
Simple two microsecond delay
io7= [HW] IO7 for Marvel based alpha systems
See comment before marvel_specify_io7 in
arch/alpha/kernel/core_marvel.c.
......
......@@ -112,4 +112,13 @@ 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
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.
endmenu
......@@ -276,10 +276,10 @@ static void putstr(const char *s)
RM_SCREEN_INFO.orig_y = y;
pos = (x + cols * y) * 2; /* Update cursor position */
outb_p(14, vidport);
outb_p(0xff & (pos >> 9), vidport+1);
outb_p(15, vidport);
outb_p(0xff & (pos >> 1), vidport+1);
outb(14, vidport);
outb(0xff & (pos >> 9), vidport+1);
outb(15, vidport);
outb(0xff & (pos >> 1), vidport+1);
}
static void* memset(void* s, int c, unsigned n)
......
......@@ -269,10 +269,10 @@ static void putstr(const char *s)
RM_SCREEN_INFO.orig_y = y;
pos = (x + cols * y) * 2; /* Update cursor position */
outb_p(14, vidport);
outb_p(0xff & (pos >> 9), vidport+1);
outb_p(15, vidport);
outb_p(0xff & (pos >> 1), vidport+1);
outb(14, vidport);
outb(0xff & (pos >> 9), vidport+1);
outb(15, vidport);
outb(0xff & (pos >> 1), vidport+1);
}
static void* memset(void* s, int c, unsigned n)
......
......@@ -8,7 +8,7 @@ CPPFLAGS_vmlinux.lds += -Ui386
obj-y := process_32.o signal_32.o entry_32.o traps_32.o irq_32.o \
ptrace_32.o time_32.o ioport_32.o ldt_32.o setup_32.o i8259_32.o sys_i386_32.o \
pci-dma_32.o i386_ksyms_32.o i387_32.o bootflag.o e820_32.o\
quirks.o i8237.o topology.o alternative.o i8253.o tsc_32.o
quirks.o i8237.o topology.o alternative.o i8253.o tsc_32.o io_delay.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-y += cpu/
......
......@@ -11,7 +11,7 @@ obj-y := process_64.o signal_64.o entry_64.o traps_64.o irq_64.o \
x8664_ksyms_64.o i387_64.o syscall_64.o vsyscall_64.o \
setup64.o bootflag.o e820_64.o reboot_64.o quirks.o i8237.o \
pci-dma_64.o pci-nommu_64.o alternative.o hpet.o tsc_64.o bugs_64.o \
i8253.o
i8253.o io_delay.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-y += cpu/
......
/*
* I/O delay strategies for inb_p/outb_p
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/delay.h>
#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
/*
* 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
/*
* Paravirt wants native_io_delay to be a constant.
*/
void native_io_delay(void)
{
io_delay();
}
EXPORT_SYMBOL(native_io_delay);
#ifndef CONFIG_UDELAY_IO_DELAY
static int __init dmi_alternate_io_delay_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;
return 0;
}
static struct dmi_system_id __initdata alternate_io_delay_port_dmi_table[] = {
{
.callback = dmi_alternate_io_delay_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);
}
#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;
else if (!strcmp(s, "udelay"))
io_delay = udelay_io_delay;
else
return -EINVAL;
#ifndef CONFIG_UDELAY_IO_DELAY
io_delay_override = 1;
#endif
return 0;
}
early_param("io_delay", io_delay_param);
......@@ -648,6 +648,8 @@ void __init setup_arch(char **cmdline_p)
dmi_scan_machine();
io_delay_init();;
#ifdef CONFIG_X86_GENERICARCH
generic_apic_probe();
#endif
......
......@@ -311,6 +311,8 @@ void __init setup_arch(char **cmdline_p)
dmi_scan_machine();
io_delay_init();
#ifdef CONFIG_SMP
/* setup to use the static apicid table during kernel startup */
x86_cpu_to_apicid_ptr = (void *)&x86_cpu_to_apicid_init;
......
......@@ -250,10 +250,14 @@ static inline void flush_write_buffers(void)
#endif /* __KERNEL__ */
static inline void native_io_delay(void)
#ifndef CONFIG_UDELAY_IO_DELAY
extern void io_delay_init(void);
#else
static inline void io_delay_init(void)
{
asm volatile("outb %%al,$0x80" : : : "memory");
}
#endif
extern void native_io_delay(void);
#if defined(CONFIG_PARAVIRT)
#include <asm/paravirt.h>
......
......@@ -35,13 +35,24 @@
* - Arnaldo Carvalho de Melo <acme@conectiva.com.br>
*/
#define __SLOW_DOWN_IO "\noutb %%al,$0x80"
#ifndef CONFIG_UDELAY_IO_DELAY
extern void io_delay_init(void);
#else
static inline void io_delay_init(void)
{
}
#endif
extern void native_io_delay(void);
static inline void slow_down_io(void)
{
native_io_delay();
#ifdef REALLY_SLOW_IO
#define __FULL_SLOW_DOWN_IO __SLOW_DOWN_IO __SLOW_DOWN_IO __SLOW_DOWN_IO __SLOW_DOWN_IO
#else
#define __FULL_SLOW_DOWN_IO __SLOW_DOWN_IO
native_io_delay();
native_io_delay();
native_io_delay();
#endif
}
/*
* Talk about misusing macros..
......@@ -50,21 +61,21 @@
static inline void out##s(unsigned x value, unsigned short port) {
#define __OUT2(s,s1,s2) \
__asm__ __volatile__ ("out" #s " %" s1 "0,%" s2 "1"
__asm__ __volatile__ ("out" #s " %" s1 "0,%" s2 "1" : : "a" (value), "Nd" (port))
#define __OUT(s,s1,x) \
__OUT1(s,x) __OUT2(s,s1,"w") : : "a" (value), "Nd" (port)); } \
__OUT1(s##_p,x) __OUT2(s,s1,"w") __FULL_SLOW_DOWN_IO : : "a" (value), "Nd" (port));} \
__OUT1(s,x) __OUT2(s,s1,"w"); } \
__OUT1(s##_p,x) __OUT2(s,s1,"w"); slow_down_io(); }
#define __IN1(s) \
static inline RETURN_TYPE in##s(unsigned short port) { RETURN_TYPE _v;
#define __IN2(s,s1,s2) \
__asm__ __volatile__ ("in" #s " %" s2 "1,%" s1 "0"
__asm__ __volatile__ ("in" #s " %" s2 "1,%" s1 "0" : "=a" (_v) : "Nd" (port))
#define __IN(s,s1,i...) \
__IN1(s) __IN2(s,s1,"w") : "=a" (_v) : "Nd" (port) ,##i ); return _v; } \
__IN1(s##_p) __IN2(s,s1,"w") __FULL_SLOW_DOWN_IO : "=a" (_v) : "Nd" (port) ,##i ); return _v; } \
#define __IN(s,s1) \
__IN1(s) __IN2(s,s1,"w"); return _v; } \
__IN1(s##_p) __IN2(s,s1,"w"); slow_down_io(); return _v; }
#define __INS(s) \
static inline void ins##s(unsigned short port, void * addr, unsigned long count) \
......
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