PCI DMA memory problem

PCI DMA memory problem

[Oliver Amft]

I am implementing a network driver for a DMA device on a custom
405GP/GPr based board. The networking device is attached over PCI bus.
Kernel is currently 2.4.21. BIOS is PPCBoot 1.2.0.

To map the data buffers from skb the driver uses pci_map_single(). When
starting the kernel with SDRAM size configurations other than 32MByte
the device is unable to transfer data (currupted data) - descriptor
dword read/write-back works (set up with pci_alloc_consistent()). For
the kernel start option mem=32MB everything is fine (descriptor +
correct data).

I am wondering if someone has stumbled over this too - any advice
appreciated.

Thanks,
Oliver


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Re: PCI DMA memory problem

[Chris Zimman]

On Tue, Jun 24, 2003 at 09:01:21PM +0200, Oliver Amft wrote:
>
> I am implementing a network driver for a DMA device on a custom
> 405GP/GPr based board. The networking device is attached over PCI bus.
> Kernel is currently 2.4.21. BIOS is PPCBoot 1.2.0.
>
> To map the data buffers from skb the driver uses pci_map_single(). When
> starting the kernel with SDRAM size configurations other than 32MByte
> the device is unable to transfer data (currupted data) - descriptor
> dword read/write-back works (set up with pci_alloc_consistent()). For
> the kernel start option mem=32MB everything is fine (descriptor +
> correct data).

My first thought is -- is/are the SDRAM bank(s) configured correctly?

I don't know that it'd necessarily be related, but for the 405GP,
PPCBoot 1.2.0 doesn't have the PCI bridge setup quite right for all
PCI devices (eg. 82559 won't work).  I have code to fix the bridge
setup if you need it -- although I'm not even certain they exist in
the GPR.

--Chris

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Re: PCI DMA memory problem

[Wolfgang Denk]

In message <20030624191935.GA9845@dingdong.cryptoapps.com> you wrote:
>
> I don't know that it'd necessarily be related, but for the 405GP,
> PPCBoot 1.2.0 doesn't have the PCI bridge setup quite right for all
> PCI devices (eg. 82559 won't work).  I have code to fix the bridge

PPCBoot-1.2.0 is more than 8 months  old.  I  recommend  updating  to
U-Boot (top of CVS).


Best regards,

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
When properly administered, vacations do not  diminish  productivity:
for every week you're away and get nothing done, there's another when
your boss is away and you get twice as much done.  -- Daniel B. Luten

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Re: PCI DMA memory problem

[Mark Powell]

We found a problem with memory-memory DMA on 405GP. Some of our h/w runs
a standalone app directly from PPCBoot. We found that DMA didn't work
at all for physical addresses below 16MByte. This applies to the data
transfers and to the scatter/gather lists.

Chris, could you send me your PCI fixes. We tried some PCI cards in a
Walnut with the idea of building a server for native compilation, but
not much worked.

Mark
--
Mark Powell, Senior Software Engineer, Primagraphics Limited
New Cambridge House, Litlington, nr.Royston, Herts, SG8 0SS, UK
Tel. +44 1763 852222, Fax. 853324, http://www.primagraphics.co.uk

----- Original Message -----
From: "Chris Zimman" <chris@cryptoapps.com>
Sent: Tuesday, June 24, 2003 8:19 PM
Subject: Re: PCI DMA memory problem

On Tue, Jun 24, 2003 at 09:01:21PM +0200, Oliver Amft wrote:
>
> I am implementing a network driver for a DMA device on a custom
> 405GP/GPr based board. The networking device is attached over PCI bus.
> Kernel is currently 2.4.21. BIOS is PPCBoot 1.2.0.
>
> To map the data buffers from skb the driver uses pci_map_single().
> When starting the kernel with SDRAM size configurations other
> than 32MByte the device is unable to transfer data (currupted
> data) - descriptor dword read/write-back works (set up with
> pci_alloc_consistent()). For the kernel start option mem=32MB
> everything is fine (descriptor + correct data).

My first thought is -- is/are the SDRAM bank(s) configured correctly?

I don't know that it'd necessarily be related, but for the 405GP,
PPCBoot 1.2.0 doesn't have the PCI bridge setup quite right for all
PCI devices (eg. 82559 won't work).  I have code to fix the bridge
setup if you need it -- although I'm not even certain they exist in
the GPR.

** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/

Re: PCI DMA memory problem

[Oliver Amft]

The problem was a wrong PCI configuration of the 405 with two colliding
PCI target mappings (PTM1 and PTM2).

Oliver

>> To map the data buffers from skb the driver uses pci_map_single().
>> When starting the kernel with SDRAM size configurations other
>> than 32MByte the device is unable to transfer data (currupted
>> data) - descriptor dword read/write-back works (set up with
>> pci_alloc_consistent()). For the kernel start option mem=32MB
>> everything is fine (descriptor + correct data).
>
> My first thought is -- is/are the SDRAM bank(s) configured correctly?
>
> I don't know that it'd necessarily be related, but for the 405GP,
> PPCBoot 1.2.0 doesn't have the PCI bridge setup quite right for all
> PCI devices (eg. 82559 won't work). I have code to fix the bridge
> setup if you need it -- although I'm not even certain they exist in
> the GPR.

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