PCI bus speed

PCI bus speed

[chen, xiangping]

Hi, 

Is there any easy way to probe the PCI bus speed
of an Intel box?

Thanks,

Xiangping

Re: PCI bus speed

[Ralf Baechle]

On Thu, Aug 02, 2001 at 06:47:49PM -0400, chen, xiangping wrote:

> Is there any easy way to probe the PCI bus speed of an Intel box?

You can find about PCI33 or PCI66 standards but there is no way to find
the exact clock rate the PCI bus is actually clocked at.  Which is a
problem with certain non-compliant cards; the IOC3 card and a few others
derive internal clocks from the PCI bus clock rate so will not properly
work if operated on a bus with different clock rate.

  Ralf

Re: PCI bus speed

[Tim Hockin]

> On Thu, Aug 02, 2001 at 06:47:49PM -0400, chen, xiangping wrote:
> 
> > Is there any easy way to probe the PCI bus speed of an Intel box?
> 
> You can find about PCI33 or PCI66 standards but there is no way to find
> the exact clock rate the PCI bus is actually clocked at.  Which is a
> problem with certain non-compliant cards; the IOC3 card and a few others
> derive internal clocks from the PCI bus clock rate so will not properly
> work if operated on a bus with different clock rate.


Also, many IDE controllers do this.  GACK!

Re: PCI bus speed

[Eric W. Biederman]

Ralf Baechle <ralf@uni-koblenz.de> writes:

> On Thu, Aug 02, 2001 at 06:47:49PM -0400, chen, xiangping wrote:
> 
> > Is there any easy way to probe the PCI bus speed of an Intel box?
> 
> You can find about PCI33 or PCI66 standards but there is no way to find
> the exact clock rate the PCI bus is actually clocked at.  

There is no portable way to find out the bus speed.  If you really
have to you can go in and stick an analyizer on the bus and measure it
but that is no help from  the software point of view.

Additionally there is not requirement that a PCI33 bus even run at
33Mhz  It can legaly run at 15Mhz to save powe if someone wants to,
and as of PCI 2.1 I believe it is perfectly legal to clock even a
PCI66 capable bus with all PCI66 capable cards down to 1Mhz.

As most systems use integrated solutions you can usually do something
like ask the northbridge of the chipset what frequency it is running
the PCI bus at.  This is code that needs to be written for every PCI
host bridge, and probably every PCI<->PCI bridge as well.

With linuxBIOS I might be able to help out a little bit by reporting
motherboard hardcodes but that is likely the most a BIOS can do.
Having a driver that understands how your northbridge chip clocks the
PCI bus goes much farther, to solving this problem.

> Which is a
> problem with certain non-compliant cards; the IOC3 card and a few others
> derive internal clocks from the PCI bus clock rate so will not properly
> work if operated on a bus with different clock rate.

Hmm.  So it looks like we need some kind of interface in linux to
propogate this information from the northbridge chip :(

Eric

Re: PCI bus speed

[Richard B. Johnson]

On Fri, 3 Aug 2001, Tim Hockin wrote:

> > yes. I see some items with flags listed as:
> > 	Flags: bus master, 66Mhz, medium devsel, latency 64, IRQ 10    
> 
> I think that reflects the '66 MHz CAPABLE' bit.  That means that IFF every
> device on the segment and IFF the bridge ALL can run at 66MHz, you MIGHT be
> at 66 MHz.  Or anywhere between 33 and 66, or for that matter, less than
> 33.
> 
> Tim

Yes, sort-of.  Bit 5 in the status register is supposed to be
"hard-wired by designer" according to the 2.2 spec. It is
TRUE if the board is capable of running at 66MHz.

However, some boards reflect the state of the bus 66MHz capable
bit. Any board that is not 66MHz capable must pull this bit to
ground (logic low). This will automatically switch a 66MHz bus
to 33MHz, usually by changing a divisor in a clock-chip.

This makes certain that any board that is not 66MHz capable will
force the bus to run at 33MHz. However, it might ALSO make any
status, bit 5  in other devices "strangely" show that they are
not 66MHz capable anymore. IOW, if I have all 66MHz devices on my
bus, and add a new board, suddenly __none__ of the devices appear
66MHz, capable. It's hard to find out the culprit without removing
boards one-at-a-time.

Cheers,
Dick Johnson

Penguin : Linux version 2.4.1 on an i686 machine (799.53 BogoMips).

    I was going to compile a list of innovations that could be
    attributed to Microsoft. Once I realized that Ctrl-Alt-Del
    was handled in the BIOS, I found that there aren't any.

Re: PCI bus speed

[Tim Hockin]

> yes. I see some items with flags listed as:
> 	Flags: bus master, 66Mhz, medium devsel, latency 64, IRQ 10    

I think that reflects the '66 MHz CAPABLE' bit.  That means that IFF every
device on the segment and IFF the bridge ALL can run at 66MHz, you MIGHT be
at 66 MHz.  Or anywhere between 33 and 66, or for that matter, less than
33.

Tim

RE: PCI bus speed

[chen, xiangping]

Todd,

Then how I can tell the bus clock rate from "lspci -v"?
Say the print out from my current machine is like:

00:00.0 Host bridge: Intel Corporation 440BX/ZX - 82443BX/ZX Host bridge
(rev 03)
        Flags: bus master, medium devsel, latency 64
        Memory at 44000000 (32-bit, prefetchable) [size=64M]
        Capabilities: <available only to root>

00:01.0 PCI bridge: Intel Corporation 440BX/ZX - 82443BX/ZX AGP bridge (rev
03) (prog-if 00 [N
ormal decode])
        Flags: bus master, 66Mhz, medium devsel, latency 64
        Bus: primary=00, secondary=01, subordinate=01, sec-latency=32
        Memory behind bridge: 40000000-40ffffff
        Prefetchable memory behind bridge: 42000000-43ffffff

00:0d.0 SCSI storage controller: Adaptec AIC-7881U (rev 01)
        Subsystem: Adaptec: Unknown device 7881
        Flags: bus master, medium devsel, latency 64, IRQ 11
        I/O ports at 1000 [size=256]
        Memory at 41100000 (32-bit, non-prefetchable) [size=4K]
        Expansion ROM at <unassigned> [disabled] [size=64K]
        Capabilities: <available only to root>

00:0e.0 Ethernet controller: Intel Corporation 82557 [Ethernet Pro 100] (rev
05)
        Subsystem: Compaq Computer Corporation NC3121 with Wake on LAN
        Flags: bus master, medium devsel, latency 66, IRQ 9
        Memory at 48000000 (32-bit, prefetchable) [size=4K]
        I/O ports at 1440 [size=32]
        Memory at 41000000 (32-bit, non-prefetchable) [size=1M]
        Capabilities: <available only to root>
 
00:10.0 Multimedia audio controller: Ensoniq ES1371 [AudioPCI-97] (rev 08)
        Subsystem: Compaq Computer Corporation: Unknown device b1a7
        Flags: bus master, slow devsel, latency 64, IRQ 5
        I/O ports at 1400 [size=64]
        Capabilities: <available only to root>
 
00:14.0 ISA bridge: Intel Corporation 82371AB PIIX4 ISA (rev 02)
        Flags: bus master, medium devsel, latency 0
 
00:14.1 IDE interface: Intel Corporation 82371AB PIIX4 IDE (rev 01) (prog-if
80 [Master])
        Flags: bus master, medium devsel, latency 64
        I/O ports at 1480 [size=16]
 
00:14.2 USB Controller: Intel Corporation 82371AB PIIX4 USB (rev 01)
(prog-if 00 [UHCI])
        Flags: bus master, medium devsel, latency 64, IRQ 5
        I/O ports at 1460 [disabled] [size=32]
 
00:14.3 Bridge: Intel Corporation 82371AB PIIX4 ACPI (rev 02)
        Flags: medium devsel
 
01:00.0 VGA compatible controller: nVidia Corporation Riva TNT2 (rev 11)
(prog-if 00 [VGA])
        Subsystem: Elsa AG: Unknown device 0c20
        Flags: bus master, 66Mhz, medium devsel, latency 64, IRQ 10
        Memory at 40000000 (32-bit, non-prefetchable) [size=16M]
        Memory at 42000000 (32-bit, prefetchable) [size=32M]
        Expansion ROM at <unassigned> [disabled] [size=64K]
        Capabilities: <available only to root>    


-----Original Message-----
From: Todd [mailto:todd@unm.edu]
Sent: Friday, August 03, 2001 11:46 AM
To: chen, xiangping
Cc: linux-kernel@vger.kernel.org
Subject: RE: PCI bus speed


chen,

i think that if you look at the speed of the bridge, that is the speed the
bridge wants to run the bus at.  as another poster noted, this doesn't
really tell you the speed the bus is actually clocked at.

t.

On Fri, 3 Aug 2001, chen, xiangping wrote:

> Date: Fri, 3 Aug 2001 10:27:10 -0400
> From: "chen, xiangping" <chen_xiangping@emc.com>
> To: 'Todd' <todd@unm.edu>
> Cc: linux-kernel@vger.kernel.org
> Subject: RE: PCI bus speed
>
> yes. I see some items with flags listed as:
> 	Flags: bus master, 66Mhz, medium devsel, latency 64, IRQ 10
>
> Is it suppose to mean that the bus freq is 66Mhz?
>
> Thanks,
>
> Xiangping
>
> -----Original Message-----
> From: Todd [mailto:todd@unm.edu]
> Sent: Thursday, August 02, 2001 8:03 PM
> To: chen, xiangping
> Cc: linux-kernel@vger.kernel.org
> Subject: Re: PCI bus speed
>
>
> xiangping,
>
> try
>
> lspci -v
>
> the info you want is there.
>
> todd
>
> On Thu, 2 Aug 2001, chen, xiangping wrote:
>
> > Date: Thu, 2 Aug 2001 18:47:49 -0400
> > From: "chen, xiangping" <chen_xiangping@emc.com>
> > To: linux-kernel@vger.kernel.org
> > Subject: PCI bus speed
> >
> > Hi,
> >
> > Is there any easy way to probe the PCI bus speed
> > of an Intel box?
> >
> > Thanks,
> >
> > Xiangping
> > -
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel"
in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/
> >
>
> =========================================================
> Todd Underwood, todd@unm.edu
>
> =========================================================
>

=========================================================
Todd Underwood, todd@unm.edu

=========================================================

RE: PCI bus speed

[Richard Gooch]

xiangping chen writes:
> yes. I see some items with flags listed as:
> 	Flags: bus master, 66Mhz, medium devsel, latency 64, IRQ 10    
> 
> Is it suppose to mean that the bus freq is 66Mhz?

I don't think so. That's the CPU<->bridge speed, not the speed that
cards plugged in could talk at.

				Regards,

					Richard....
Permanent: rgooch@atnf.csiro.au
Current:   rgooch@ras.ucalgary.ca

RE: PCI bus speed

[Todd]

chen,

i think that if you look at the speed of the bridge, that is the speed the
bridge wants to run the bus at.  as another poster noted, this doesn't
really tell you the speed the bus is actually clocked at.

t.

On Fri, 3 Aug 2001, chen, xiangping wrote:

> Date: Fri, 3 Aug 2001 10:27:10 -0400
> From: "chen, xiangping" <chen_xiangping@emc.com>
> To: 'Todd' <todd@unm.edu>
> Cc: linux-kernel@vger.kernel.org
> Subject: RE: PCI bus speed
>
> yes. I see some items with flags listed as:
> 	Flags: bus master, 66Mhz, medium devsel, latency 64, IRQ 10
>
> Is it suppose to mean that the bus freq is 66Mhz?
>
> Thanks,
>
> Xiangping
>
> -----Original Message-----
> From: Todd [mailto:todd@unm.edu]
> Sent: Thursday, August 02, 2001 8:03 PM
> To: chen, xiangping
> Cc: linux-kernel@vger.kernel.org
> Subject: Re: PCI bus speed
>
>
> xiangping,
>
> try
>
> lspci -v
>
> the info you want is there.
>
> todd
>
> On Thu, 2 Aug 2001, chen, xiangping wrote:
>
> > Date: Thu, 2 Aug 2001 18:47:49 -0400
> > From: "chen, xiangping" <chen_xiangping@emc.com>
> > To: linux-kernel@vger.kernel.org
> > Subject: PCI bus speed
> >
> > Hi,
> >
> > Is there any easy way to probe the PCI bus speed
> > of an Intel box?
> >
> > Thanks,
> >
> > Xiangping
> > -
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/
> >
>
> =========================================================
> Todd Underwood, todd@unm.edu
>
> =========================================================
>

=========================================================
Todd Underwood, todd@unm.edu

=========================================================

Re: PCI bus speed

[Ralf Baechle]

On Fri, Aug 03, 2001 at 10:27:10AM -0400, chen, xiangping wrote:

> yes. I see some items with flags listed as:
> 	Flags: bus master, 66Mhz, medium devsel, latency 64, IRQ 10    
> 
> Is it suppose to mean that the bus freq is 66Mhz?

Not necessarily ...

  Ralf

RE: PCI bus speed

[chen, xiangping]

yes. I see some items with flags listed as:
	Flags: bus master, 66Mhz, medium devsel, latency 64, IRQ 10    

Is it suppose to mean that the bus freq is 66Mhz?

Thanks,

Xiangping

-----Original Message-----
From: Todd [mailto:todd@unm.edu]
Sent: Thursday, August 02, 2001 8:03 PM
To: chen, xiangping
Cc: linux-kernel@vger.kernel.org
Subject: Re: PCI bus speed


xiangping,

try

lspci -v

the info you want is there.

todd

On Thu, 2 Aug 2001, chen, xiangping wrote:

> Date: Thu, 2 Aug 2001 18:47:49 -0400
> From: "chen, xiangping" <chen_xiangping@emc.com>
> To: linux-kernel@vger.kernel.org
> Subject: PCI bus speed
>
> Hi,
>
> Is there any easy way to probe the PCI bus speed
> of an Intel box?
>
> Thanks,
>
> Xiangping
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
>

=========================================================
Todd Underwood, todd@unm.edu

=========================================================