Re: FireWire + Apple PB G3: some success

[Andreas Bombe <andreas.bombe@munich.netsurf.de>]

On Thu, Feb 24, 2000 at 05:44:53AM +0300, Maxim S. Shatskih wrote:
> > It's not seen because the driver is stuck in bus reset.  The most
> > probable reason is that DMA is not working.  I can't think of a reason
> > right now (since it does work on another PPC).
>
> I've had this problem on NT4. Are you sure that the DMA enable bit in PCI
> config space is set?

To quote Albert's patch:

 +       pci_read_config_word (dev, PCI_COMMAND, &w);
 +       pci_write_config_word (dev, PCI_COMMAND, w | PCI_COMMAND_MASTER | PCI_COMMAND_MEMORY | PCI_COMMAND_IO);

He sets the PCI master flag (which should be the only thing disabling /
enabling DMA in general).  In the standard sources pci_set_master() is
used, which does the same.

Setting PCI_COMMAND_IO on the other hand is unneccessary since the
PCILynx only uses memory mapped I/O (if I understand PCI config
correctly).  I don't know if this flag is harmful if there are no I/O
ports.

--
          Andreas E. Bombe <andreas.bombe@munich.netsurf.de>
http://home.pages.de/~andreas.bombe/                DSA key 0x04880A44

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