[U-Boot] [PATCH 1/5] net: ll_temac: Add LL TEMAC driver to u-boot

[Stephan Linz]

Am Sonntag, den 15.01.2012, 13:47 -0500 schrieb Mike Frysinger: 
> On Sunday 15 January 2012 13:29:26 Stephan Linz wrote:
> > Am Sonntag, den 15.01.2012, 12:28 -0500 schrieb Mike Frysinger:
> > > On Sunday 15 January 2012 10:46:02 Stephan Linz wrote:
> > > > +/* Data buffer for LL TEMAC Rx and Tx direction */
> > > > +static unsigned char rx_buffer[PKTSIZE_ALIGN]
> > > > __attribute((aligned(DMAALIGN)));
> > > > +static unsigned char tx_buffer[PKTSIZE_ALIGN]
> > > > __attribute((aligned(DMAALIGN)));
> > > 
> > > come code already declares PktBuf ... can't you use that ?
> > 
> > Hm, what do you mean exactly here?
> > 
> > These are the two DMA transfer buffers. I have no idea if there are
> > buffers in the upper layer (NET) and how I can use it for DMA transfers.
> > Therfore I create my own rx/tx buffers and copy data. That reduce the
> > performance a little bit, but it's OK. Furthermore I have to use DMA
> > safe buffers here (no cache, 32 byte alignment).
> 
> from doc/README.drivers.eth:
> The recv function should process packets as long as the hardware has them 
> readily available before returning.  i.e. you should drain the hardware fifo. 
> For each packet you receive, you should call the NetReceive() function on it 
> along with the packet length.  The common code sets up packet buffers for you 
> already in the .bss (NetRxPackets), so there should be no need to allocate 
> your own.
> 
> so you already have an array of packet buffers declared for you.  the first one 
> is &NetRxPackets[0], etc...  since you're just DMA-ing to random external 
> memory, i don't think the address matters.

Hello Mike
and all others,

is there already a simple ETH driver that use these kind of buffer
handling? Up to now I've learned from the Freescale TSEC driver,
especially the MDIO bus implementation. It seems this driver implement
this packet buffer, or not?

> 
> the core code atm however doesn't align things at all, so we'll have to fix 
> that before this driver could use it.

Is the TSEC driver DMA alignment safe (especially the DMA buffer data,
not the DMA buffer descriptor)? What do I need to make the internal
array of packet buffer DMA secure (cache, alignment)?


-- 
Best regards,
Stephan Linz
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