Re: [PATCH] ks8842: Support DMA when accessed via timberdale

[David Miller <davem@davemloft.net>]

From: Richard Röjfors <richard.rojfors@pelagicore.com>
Date: Tue, 27 Jul 2010 11:18:17 +0200

> This patch adds support for RX and TX DMA via the DMA API,
> this is only supported when the KS8842 is accessed via timberdale.
> 
> There is no support for DMA on the generic bus interface it self,
> a state machine inside the FPGA is handling RX and TX transfers to/from
> buffers in the FPGA. The host CPU can do DMA to and from these buffers.
> 
> The FPGA has to handle the RX interrupts, so these must be enabled in
> the ks8842 but not in the FPGA. The driver must not disable the RX interrupt
> that would mean that the data transfers into the FPGA buffers would stop.
> 
> The host shall not enable TX interrupts since TX is handled by the FPGA,
> the host is notified by DMA callbacks when transfers are finished.
> 
> Which DMA channels to use are added as parameters in the platform data struct.
> 
> Signed-off-by: Richard Röjfors <richard.rojfors@pelagicore.com>

Please, no more crazy config options, make the code dynamically use
DMA or not based upon information passed in via the platform_device
object at probe time.