Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops

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To: Alan Cox <alan@...>
Cc: David Newall <david@...>, Rene Herman <rene.herman@...>, Paul Rolland <rol@...>, H. Peter Anvin <hpa@...>, Krzysztof Halasa <khc@...>, Pavel Machek <pavel@...>, Andi Kleen <andi@...>, <linux-kernel@...>, Thomas Gleixner <tglx@...>, Ingo Molnar <mingo@...>, <rol@...>
Date: Thursday, December 13, 2007 - 9:13 am

Perhaps what was meant is that ISA-tuned timings make little sense on 
devices that are part of the chipset or on the PCI or PCI-X buses?

On the other hand, since we don't know in many cases whether the "_p" 
was supposed to mean "the time it takes to execute an "out al,80h" on 
whatever bus structure happens to be on whatever machine, the problem is 
unsolvable.

Ranting about whether ISA/LPC is on what machines seems to be of little 
value in contributing to a constructive solution.

It seems to me that in the long term, driver writers would do well to 
think more clearly about the timings their devices require, when that is 
possible.   They are probably implementation dependent - depending on 
the clock speed of the particular clock that is driving the particular 
i/o device.

Then there's the social problem of a community development project - 
which is to get people to tune their code but preserve its ability to 
run on older and variant machines.

Alan Cox wrote:
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Messages in current thread:
Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern A..., linux-os (Dick Johnson), (Tue Dec 11, 11:41 am)
More info on port 80 symptoms on MCP51 machine., David P. Reed, (Wed Dec 12, 4:07 pm)
Re: More info on port 80 symptoms on MCP51 machine., Rene Herman, (Wed Dec 12, 4:26 pm)
Re: More info on port 80 symptoms on MCP51 machine., Rene Herman, (Wed Dec 12, 4:58 pm)
Re: More info on port 80 symptoms on MCP51 machine., H. Peter Anvin, (Wed Dec 12, 5:05 pm)
Re: More info on port 80 symptoms on MCP51 machine., Chuck Ebbert, (Fri Dec 14, 6:05 pm)
Re: More info on port 80 symptoms on MCP51 machine., Rene Herman, (Sat Dec 15, 3:22 am)
Re: More info on port 80 symptoms on MCP51 machine., H. Peter Anvin, (Wed Dec 12, 5:12 pm)
RE: More info on port 80 symptoms on MCP51 machine., Allen Martin, (Sat Dec 15, 6:34 pm)
Re: More info on port 80 symptoms on MCP51 machine., H. Peter Anvin, (Sat Dec 15, 6:46 pm)
Re: More info on port 80 symptoms on MCP51 machine., David P. Reed, (Wed Dec 12, 4:37 pm)
Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern A..., David P. Reed, (Thu Dec 13, 9:13 am)
Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern A..., linux-os (Dick Johnson), (Tue Dec 11, 4:27 pm)
Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern A..., linux-os (Dick Johnson), (Wed Dec 12, 9:11 am)
Attitude problems., David P. Reed, (Wed Dec 12, 3:42 pm)
Re: Attitude problems., linux-os (Dick Johnson), (Wed Dec 12, 4:31 pm)
Re: Attitude problems., linux-os (Dick Johnson), (Fri Dec 14, 12:01 pm)
Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern A..., Dr. David Alan Gilbert, (Sun Dec 9, 9:41 am)
Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern A..., Lennart Sorensen, (Tue Dec 11, 11:14 am)