linux-kernel - Re: [PATCH] x86: provide a DMI based port 0x80 I/O delay override.

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Date:	Mon, 17 Dec 2007 14:09:33 +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 17-12-07 11:57, Ingo Molnar wrote:
>
>> 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.
>
> "appropriated it", more. [...]

huh?

> [...] Definitely not going to forgive you for deleting that comment.

Do you mean:

+/*
+ * High on a hill was a lonely goatherd
+ */

?

>>  void native_io_delay(void)
>>  {
>> -	io_delay();
>> +	switch (io_delay_type) {
>
> That's the clumsy bit. native_io_delay() used to be an inline outb, 
> now it's a switch. Yes, sure, versus an indirect call it's not 
> actually worse, except as an uglification.

the switch enableds the sysctl. I dont see the callback as in any way 
cleaner. (in fact it made things more inflexible.)

>> -#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;
>>  }
>
> This isn't correct. DMI shouldn't override the CONFIG choice or 
> someone with matching DMI will have a defective CONFIG option. That's 
> why I put all of it inside #ifndef.

no, the DMI quirk is just that: a quirk that makes boxes work. The DMI 
quirk takes precedence over just about any .config default, except an 
explicit boot-commandline override.

	Ingo
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