Message-Id: <1198979361.11150.2.camel@iamer-laptop>
Date:	Sun, 30 Dec 2007 03:49:21 +0200
From:	Islam Amer <pharon@...il.com>
To:	Rene Herman <rene.herman@...access.nl>
Cc:	"David P. Reed" <dpreed@...d.com>,
	Richard Harman <richard@...hardharman.com>,
	Eduard-Gabriel Munteanu <eduard.munteanu@...ux360.ro>,
	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH] Option to disable AMD C1E (allows dynticks to work)

Glad I could be of help.

Sure please go ahead, I will keep testing this patch with upcoming git
kernels, and report any problems.

So what I understand now is that AMD C1E state saves battery like
dynticks, so we don't need dynticks ?

On Sun, 2007-12-30 at 02:38 +0100, Rene Herman wrote:
> On 29-12-07 23:28, Islam Amer wrote:
> 
> > Thanks for the detailed response.
> > 
> > I thought I had gotten to the bottom of my problems when I found that
> > udev workaround, I guess I was naive.
> > 
> > I did the two tests you described and they predictably caused the hard
> > hangs. I needed to run the port80 program only once to get the hard
> > hang.
> > 
> > The output of the dmidecode commands were :
> > 
> > Quanta
> > 30B7
> > 
> > I applied the patch you provided ( luckily I am using 2.6.24-rc6-git3
> > kernel because I need the b43 driver ), added these values and compiled.
> > 
> > 
> > 	{
> > 		.callback	= dmi_io_delay_port_alt,
> > 		.ident		= "Compaq Presario v6000",
> > 		.matches	= {
> > 			DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
> > 			DMI_MATCH(DMI_BOARD_NAME, "30B7")
> > 		}
> > 	},
> > 
> > I was able to boot without the udev workaround and can now use hwclock
> > without hanging the system. In dmesg I can see this new line :
> 
> Thanks much for testing (and David -- thanks for asking). Updated patch 
> attached with this information. Compaq itself seems to spell the type with a 
> capital V so that's the only difference...
> 
> Can I add a "Tested-by: Islam Amer <pharon@...il.com>" to this? (and David, 
> same for you with this address you're using in this thread?)
> 
> Rene.
> plain text document attachment (dmi-port80-minimal-bootparam.diff)
> commit 5f27525d3e796ae12e3186afe8ef0ec41af9e160
> Author: Rene Herman <rene.herman@...il.com>
> Date:   Mon Dec 17 21:23:55 2007 +0100
> 
>     x86: provide a DMI based port 0x80 I/O delay override.
>     
>     Certain (HP/Compaq) 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 using port 0xed works and provides a
>     proper delay on his HP Pavilion dv9000z, Islam Amer comfirmed that
>     it does so on a Compaq Presario V6000. Both are Quanta boards, type
>     30B9 and 30B7 respectively and are the (only) machines for which
>     the DMI based switch triggers. HP Pavilion dv6000z is expected to
>     also need this but its DMI info hasn't been verified yet.
>     
>     The symptoms of _not_ working are a hanging machine, with "hwclock"
>     use being a direct trigger and therefore the bootup often hanging
>     already on these machines.
>     
>     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 still leaves:
>     
>     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 various drivers are 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.
>     
>     An early boot parameter to make the choice manually (and override any
>     possible DMI based decision) is also provided:
>     
>     	io_delay=standard|alternate
>     
>     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 tested by David P. Reed. 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 leaving the ones in the
>     boot code be is safe.
>     
>     This patch is partly based on earlier patches from Pavel Machek and
>     David P. Reed.
>     
>     Signed-off-by: Rene Herman <rene.herman@...il.com>
> 
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index 33121d6..6948e25 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -785,6 +785,12 @@ 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 port
> +		standard
> +			Use the 0x80 standard I/O delay port (default)
> +		alternate
> +			Use the 0xed alternate I/O delay port
> +
>  	io7=		[HW] IO7 for Marvel based alpha systems
>  			See comment before marvel_specify_io7 in
>  			arch/alpha/kernel/core_marvel.c.
> diff --git a/arch/x86/boot/compressed/misc_32.c b/arch/x86/boot/compressed/misc_32.c
> index b74d60d..288e162 100644
> --- a/arch/x86/boot/compressed/misc_32.c
> +++ b/arch/x86/boot/compressed/misc_32.c
> @@ -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)
> diff --git a/arch/x86/boot/compressed/misc_64.c b/arch/x86/boot/compressed/misc_64.c
> index 6ea015a..43e5fcc 100644
> --- a/arch/x86/boot/compressed/misc_64.c
> +++ b/arch/x86/boot/compressed/misc_64.c
> @@ -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)
> diff --git a/arch/x86/kernel/Makefile_32 b/arch/x86/kernel/Makefile_32
> index a7bc93c..0cc1981 100644
> --- a/arch/x86/kernel/Makefile_32
> +++ b/arch/x86/kernel/Makefile_32
> @@ -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-$(CONFIG_STACKTRACE)	+= stacktrace.o
>  obj-y				+= cpu/
> diff --git a/arch/x86/kernel/Makefile_64 b/arch/x86/kernel/Makefile_64
> index 5a88890..08a68f0 100644
> --- a/arch/x86/kernel/Makefile_64
> +++ b/arch/x86/kernel/Makefile_64
> @@ -11,7 +11,7 @@ obj-y	:= process_64.o signal_64.o entry_64.o traps_64.o irq_64.o \
>  		x8664_ksyms_64.o i387_64.o syscall_64.o vsyscall_64.o \
>  		setup64.o bootflag.o e820_64.o reboot_64.o quirks.o i8237.o \
>  		pci-dma_64.o pci-nommu_64.o alternative.o hpet.o tsc_64.o bugs_64.o \
> -		i8253.o
> +		i8253.o io_delay.o
>  
>  obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
>  obj-y				+= cpu/
> diff --git a/arch/x86/kernel/io_delay.c b/arch/x86/kernel/io_delay.c
> new file mode 100644
> index 0000000..77a8bcd
> --- /dev/null
> +++ b/arch/x86/kernel/io_delay.c
> @@ -0,0 +1,77 @@
> +/*
> + * I/O delay strategies for inb_p/outb_p
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/dmi.h>
> +#include <asm/io.h>
> +
> +/*
> + * Allow for a DMI based override of port 0x80
> + */
> +#define IO_DELAY_PORT_STD 0x80
> +#define IO_DELAY_PORT_ALT 0xed
> +
> +static unsigned short io_delay_port __read_mostly = IO_DELAY_PORT_STD;
> +
> +void native_io_delay(void)
> +{
> +	asm volatile ("outb %%al, %w0" : : "d" (io_delay_port));
> +}
> +EXPORT_SYMBOL(native_io_delay);
> +
> +static int __init dmi_io_delay_port_alt(const struct dmi_system_id *id)
> +{
> +	printk(KERN_NOTICE "%s: using alternate I/O delay port\n", id->ident);
> +	io_delay_port = IO_DELAY_PORT_ALT;
> +	return 0;
> +}
> +
> +static struct dmi_system_id __initdata dmi_io_delay_port_alt_table[] = {
> +	{
> +		.callback	= dmi_io_delay_port_alt,
> +		.ident		= "Compaq Presario V6000",
> +		.matches	= {
> +			DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
> +			DMI_MATCH(DMI_BOARD_NAME, "30B7")
> +		}
> +	},
> +	{
> +		.callback	= dmi_io_delay_port_alt,
> +		.ident		= "HP Pavilion dv9000z",
> +		.matches	= {
> +			DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
> +			DMI_MATCH(DMI_BOARD_NAME, "30B9")
> +		}
> +	},
> +	{
> +	}
> +};
> +
> +static int __initdata io_delay_override;
> +
> +static int __init io_delay_param(char *s)
> +{
> +	if (!s)
> +		return -EINVAL;
> +
> +	if (!strcmp(s, "standard"))
> +		io_delay_port = IO_DELAY_PORT_STD;
> +	else if (!strcmp(s, "alternate"))
> +		io_delay_port = IO_DELAY_PORT_ALT;
> +	else
> +		return -EINVAL;
> +
> +	io_delay_override = 1;
> +	return 0;
> +}
> +
> +early_param("io_delay", io_delay_param);
> +
> +void __init io_delay_init(void)
> +{
> +	if (!io_delay_override)
> +		dmi_check_system(dmi_io_delay_port_alt_table);
> +}
> diff --git a/arch/x86/kernel/setup_32.c b/arch/x86/kernel/setup_32.c
> index e1e18c3..6c3a3b4 100644
> --- a/arch/x86/kernel/setup_32.c
> +++ b/arch/x86/kernel/setup_32.c
> @@ -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	
> diff --git a/arch/x86/kernel/setup_64.c b/arch/x86/kernel/setup_64.c
> index 30d94d1..ec976ed 100644
> --- a/arch/x86/kernel/setup_64.c
> +++ b/arch/x86/kernel/setup_64.c
> @@ -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;
> diff --git a/include/asm-x86/io_32.h b/include/asm-x86/io_32.h
> index fe881cd..690b8f4 100644
> --- a/include/asm-x86/io_32.h
> +++ b/include/asm-x86/io_32.h
> @@ -250,10 +250,8 @@ static inline void flush_write_buffers(void)
>  
>  #endif /* __KERNEL__ */
>  
> -static inline void native_io_delay(void)
> -{
> -	asm volatile("outb %%al,$0x80" : : : "memory");
> -}
> +extern void io_delay_init(void);
> +extern void native_io_delay(void);
>  
>  #if defined(CONFIG_PARAVIRT)
>  #include <asm/paravirt.h>
> diff --git a/include/asm-x86/io_64.h b/include/asm-x86/io_64.h
> index a037b07..b2d4994 100644
> --- a/include/asm-x86/io_64.h
> +++ b/include/asm-x86/io_64.h
> @@ -35,13 +35,18 @@
>    *  - Arnaldo Carvalho de Melo <acme@...ectiva.com.br>
>    */
>  
> -#define __SLOW_DOWN_IO "\noutb %%al,$0x80"
> +extern void io_delay_init(void);
> +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 +55,21 @@
>  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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