PCI-X support

PCI-X support

[christos gentsis]

Hello

I have a friend that his Msc project is related with the development 
over a PCI-X card. the problem is that he do not know if the Linux 
kernel support the PCI-X bus. i try to find something related with the 
PCI-X in the kernel source but i didn't found any file or folder with a 
relevant name... Does any one know if PCI-X bus supported from Linux and 
if no how can he patch the kernel to support it...?

Thanks
Chris

Re: PCI-X support

[Richard B. Johnson]

On Fri, 1 Jul 2005, christos gentsis wrote:

> Hello
>
> I have a friend that his Msc project is related with the development
> over a PCI-X card. the problem is that he do not know if the Linux
> kernel support the PCI-X bus. i try to find something related with the
> PCI-X in the kernel source but i didn't found any file or folder with a
> relevant name... Does any one know if PCI-X bus supported from Linux and
> if no how can he patch the kernel to support it...?
>
> Thanks
> Chris

Sure PCI-X is just PCI/66 with 64-bits. It's just like PCI/66
from a software standpoint.


Cheers,
Dick Johnson
Penguin : Linux version 2.6.12 on an i686 machine (5537.79 BogoMips).
  Notice : All mail here is now cached for review by Dictator Bush.
                  98.36% of all statistics are fiction.

Re: PCI-X support

[christos gentsis]

Richard B. Johnson wrote:

> On Fri, 1 Jul 2005, christos gentsis wrote:
>
>> Hello
>>
>> I have a friend that his Msc project is related with the development
>> over a PCI-X card. the problem is that he do not know if the Linux
>> kernel support the PCI-X bus. i try to find something related with the
>> PCI-X in the kernel source but i didn't found any file or folder with a
>> relevant name... Does any one know if PCI-X bus supported from Linux and
>> if no how can he patch the kernel to support it...?
>>
>> Thanks
>> Chris
>
>
> Sure PCI-X is just PCI/66 with 64-bits. It's just like PCI/66
> from a software standpoint.
>
>
> Cheers,
> Dick Johnson
> Penguin : Linux version 2.6.12 on an i686 machine (5537.79 BogoMips).
>  Notice : All mail here is now cached for review by Dictator Bush.
>                  98.36% of all statistics are fiction.
>
so this practically means that hi will plug the card in, install Linux 
and the card will work correctly? because normal PCI i think that is 
32-bit... does the same driver will provide full support?

Re: PCI-X support

[Vojtech Pavlik]

On Fri, Jul 01, 2005 at 02:00:15PM -0400, Richard B. Johnson wrote:
> On Fri, 1 Jul 2005, christos gentsis wrote:
> 
> >Hello
> >
> >I have a friend that his Msc project is related with the development
> >over a PCI-X card. the problem is that he do not know if the Linux
> >kernel support the PCI-X bus. i try to find something related with the
> >PCI-X in the kernel source but i didn't found any file or folder with a
> >relevant name... Does any one know if PCI-X bus supported from Linux and
> >if no how can he patch the kernel to support it...?
> >
> >Thanks
> >Chris
> 
> Sure PCI-X is just PCI/66 with 64-bits. It's just like PCI/66
> from a software standpoint.
 
Not really. 64-bit 66MHz PCI is normal PCI, within the PCI 2.1 spec.
Common PCI-X is running at 133MHz, 64-bit wide.

You're correct, though, that from the software standpoint it's not much
different and Linux supports it natively. I'm not sure about MSI-X
extensions, though.

-- 
Vojtech Pavlik
SuSE Labs, SuSE CR

Re: PCI-X support

[Richard B. Johnson]

On Fri, 1 Jul 2005, christos gentsis wrote:

> Richard B. Johnson wrote:
>
>> On Fri, 1 Jul 2005, christos gentsis wrote:
>>
>>> Hello
>>>
>>> I have a friend that his Msc project is related with the development
>>> over a PCI-X card. the problem is that he do not know if the Linux
>>> kernel support the PCI-X bus. i try to find something related with the
>>> PCI-X in the kernel source but i didn't found any file or folder with a
>>> relevant name... Does any one know if PCI-X bus supported from Linux and
>>> if no how can he patch the kernel to support it...?
>>>
>>> Thanks
>>> Chris
>>
>>
>> Sure PCI-X is just PCI/66 with 64-bits. It's just like PCI/66
>> from a software standpoint.
>>
>>
>> Cheers,
>> Dick Johnson
>> Penguin : Linux version 2.6.12 on an i686 machine (5537.79 BogoMips).
>>  Notice : All mail here is now cached for review by Dictator Bush.
>>                  98.36% of all statistics are fiction.
>>
> so this practically means that hi will plug the card in, install Linux
> and the card will work correctly? because normal PCI i think that is
> 32-bit... does the same driver will provide full support?
>

The driver (whatever that is), if it was written for a 64-bit
platform, can write a 64-bit word in one operation and it's
transparent. If the driver was written for a 32-bit environment,
it will still work because there is compatibility with PCI 2.x

FYI, this machine has a PCI-X bus. I have some 32-bit cards
plugged into it (SCSI controller, etc.). They work. I also
have a 64-bit card plugged into it (fiber-optic data link).
It also works, but at 133 MHz. Software never talks to it
in 'long longs' so the increased data-width isn't being used.

Warning!  Many 5-volt cards may not work on the PCI-X bus.


Cheers,
Dick Johnson
Penguin : Linux version 2.6.12 on an i686 machine (5537.79 BogoMips).
  Notice : All mail here is now cached for review by Dictator Bush.
                  98.36% of all statistics are fiction.

Re: PCI-X support

[Greg KH]

On Fri, Jul 01, 2005 at 06:48:51PM +0100, christos gentsis wrote:
> Hello
> 
> I have a friend that his Msc project is related with the development 
> over a PCI-X card. the problem is that he do not know if the Linux 
> kernel support the PCI-X bus.

Yes.  But I don't think we support PCI-X 2.0, but as there are no
chipsets out yet that support that, I don't think you should worry about
that :)

Good luck,

greg k-h

Re: PCI-X support

[Vojtech Pavlik]

On Fri, Jul 01, 2005 at 03:02:11PM -0400, Richard B. Johnson wrote:

> The driver (whatever that is), if it was written for a 64-bit
> platform, can write a 64-bit word in one operation and it's
> transparent. If the driver was written for a 32-bit environment,
> it will still work because there is compatibility with PCI 2.x
> 
> FYI, this machine has a PCI-X bus. I have some 32-bit cards
> plugged into it (SCSI controller, etc.). They work. I also
> have a 64-bit card plugged into it (fiber-optic data link).
> It also works, but at 133 MHz. Software never talks to it
> in 'long longs' so the increased data-width isn't being used.

Are you sure about that? I'd assume when doing busmastering, it'll use
64-bit transfers, if the driver sets the correct DMA mask.

-- 
Vojtech Pavlik
SuSE Labs, SuSE CR

Re: PCI-X support

[Richard B. Johnson]

On Fri, 1 Jul 2005, Vojtech Pavlik wrote:

> On Fri, Jul 01, 2005 at 03:02:11PM -0400, Richard B. Johnson wrote:
>
>> The driver (whatever that is), if it was written for a 64-bit
>> platform, can write a 64-bit word in one operation and it's
>> transparent. If the driver was written for a 32-bit environment,
>> it will still work because there is compatibility with PCI 2.x
>>
>> FYI, this machine has a PCI-X bus. I have some 32-bit cards
>> plugged into it (SCSI controller, etc.). They work. I also
>> have a 64-bit card plugged into it (fiber-optic data link).
>> It also works, but at 133 MHz. Software never talks to it
>> in 'long longs' so the increased data-width isn't being used.
>
> Are you sure about that? I'd assume when doing busmastering, it'll use
> 64-bit transfers, if the driver sets the correct DMA mask.
>

Yep. The board uses a PLX PCI 9656BA chip configured for local-bus
transfers during DMA The local-bus is 32-bits from a FIFO. There
is no way to collapse these writes from the 32-bit source/dest.
The transfers are 32 quadwords for a write and 16 quadwords for
a read, but that represents a burst, not the data-width. Without
a 64-bit data-path to memory on one side, and a 64-bit data-path
to the device (a FIFO) on the other side, you will not get 64-bit
transfers.


> -- 
> Vojtech Pavlik
> SuSE Labs, SuSE CR
> -

Cheers,
Dick Johnson
Penguin : Linux version 2.6.12 on an i686 machine (5537.79 BogoMips).
  Notice : All mail here is now cached for review by Dictator Bush.
                  98.36% of all statistics are fiction.

Re: PCI-X support

[Krzysztof Halasa]

"Richard B. Johnson" <linux-os@analogic.com> writes:

> Yep. The board uses a PLX PCI 9656BA chip configured for local-bus
> transfers during DMA The local-bus is 32-bits from a FIFO. There
> is no way to collapse these writes from the 32-bit source/dest.
> The transfers are 32 quadwords for a write and 16 quadwords for
> a read, but that represents a burst, not the data-width. Without
> a 64-bit data-path to memory on one side, and a 64-bit data-path
> to the device (a FIFO) on the other side, you will not get 64-bit
> transfers.

I don't know about this particular bridge, but in general you can
have 64-bit transfers over PCI(-X) corresponding to 32-bit transfers
over local bus. The local bus has to be twice as fast as PCI bus or
you won't be able to saturate PCI bus. Especially if it's the bridge
doing PCI BM DMA transfers (and not, say, another processor on the
local bus).
-- 
Krzysztof Halasa