Re: [ECOS] PowerPC FEC problems

[ken king <kknhuntsville at yahoo dot com>]

--- Andrew Lunn <andrew@lunn.ch> wrote:
> > > Check the addresses you are using from receive
> and
> > > transmit buffers.
> > > Do you remember to map the virtual addresses
> into
> > > bus addresses before
> > > programming them into the ethernet device? Does
> > > memory realy exist at
> > > the address? 
> > > 
> > >         Andrew
> > > 
> > > -- 
> > > Before posting, please read the FAQ:
> > > http://ecos.sourceware.org/fom/ecos
> > > and search the list archive:
> > > http://ecos.sourceware.org/ml/ecos-discuss
> > > 
> > Yes, I can dump memory around the BDs (Buffer
> > descriptors) and they look correct. The memory
> > pointed to by the BD can also be dumped and it
> > has the same contents as displayed on the
> > console if eth debugging is on, i.e looks like the
> > bootp frames. I can put a scope on the PHYs
> > tx_clock and tx_en -- the clock is running, but
> > tx_en is never asserted.
> 
> You can look at the memory from the processor, so
> you know you have
> the correct virtual address. However, the DMA might
> not be using the
> virtual address. It will be using some bus address.
> Bus addresses can
> be different from virtual addresses. Read the
> datasheet and see what
> it says about the addresses to be used for
> programming the DMA engine.
> 
>         Andrew
> 
> -- 
> Before posting, please read the FAQ:
> http://ecos.sourceware.org/fom/ecos
> and search the list archive:
> http://ecos.sourceware.org/ml/ecos-discuss
> 
> 
I thought that the MMU was off -- the config tool has
it grayed out. However the MMU is on. Just for fun, I
disabled it. It would appear that physical addr =
virtual addr. I still get the bus error after
verifying the MMU is disabled before and after. I also
checked that the BDs are correct before and after.

As for the data book, it doesn?t say much about the
FEC DMA ? it seems to imply that it is different from
the SDMA which got it?s own section.

Thanks,
kk



		
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