PCI DMA memory problem

Oliver Amft oam at gmx.net
Wed Jun 25 05:01:21 EST 2003

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


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