Re: DMA support for smc91x

[tony@atomide.com]

* Ladislav Michl <ladis@linux-mips.org> [060323 16:23]:
> Hi,
> 
> this mail contains dirty and for most people completely useless patch.
> Here is my motivation for it: I have OMAP based board using LAN91C111,
> its interrupt line is routed to GPIO pin. Other GPIO lines are used as
> interrupt sources for ISDN chips which needs to be services regulary
> (irq can be generated per 125us for each of four chips). All interrupts
> from GPIOs are serialized, so if smc91x needs 1.6ms to read 8 full size
> packets from memory, communication with ISDN chips gets screwed. Even
> decreasing MAX_IRQ_LOOPS to 1 doesn't help too much here, because single
> full size packet reading takes 200us. Now programing DMA takes only 6us
> and rest of CPU time is left for sometning usesfull :-). Patch is
> pre-alpha quality, there are some locking bugs - reading from eeprom
> while DMA is progress will result in undefined behaviour (but there
> is not eeprom support upstream, so who cares ;-)) - and I just want to
> ask if anyone else would need something it and provide some feedback.
> Then I may think a bit more, finish it and send it to proper mailing
> list.

That's cool :)

Tony