[spi-devel-general] [PATCH] Adapt spi_mpc83xx SPI driver for 832x

[Kumar Gala]

On Dec 22, 2006, at 7:09 PM, David Brownell wrote:

> On Thursday 14 December 2006 2:02 am, Joakim Tjernlund wrote:
>
>> Adjusted patch(lets hope I didn't mangle this one:):
>
> Assuming this is correct, I don't have a problem with this one.
> Feel free to wrap it up with a signed-off-by and I'll forward it.

I'll cleanup the patches and send something to you.

> I have a question for someone who knows about this controller  
> though...
>
> When issuing an RX-only transfer, the SPI framework currently  
> specifies
> that spi_transfer.tx_buf will be null, and that the data shifted out
> on the MOSI pin is "undefined".  Looking at the spi_mpc83xx driver in
> the current tree, it looked to me as if it wouldn't actually accept
> a null tx_buf ... did I miss something, or would the tx_buf##type  
> macros
> expand to a null pointer exception?  If I did miss something, what  
> data
> would be shifted out in that case?  (IRQ vectors from page zero?)

Yeah this is a bug, your not missing anything.  Would be good if this  
fix could go into 2.6.20.

> There's a proposal afoot to change how that's specified:  rather than
> shifting out "undefined" data, define it as all zeroes.  It was easy
> to see the impact of that on all the other SPI controller drivers now
> upstream; all but one send zeroes already.  But not this one...
>
> - Dave

[snip]