Re: DMA breakage in 2.6.29-rc*

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

> Yeah my bad, though thanks to Andreas Schwab it is fixed in -rc3.

Hrm... I was using rc3 here and had the bug. I'll dig to check it's
really that or something else and send a patch if needed.

> Would be great as I have completely no idea about this stuff.

No worries.

> While you are at DMA support and will be fixing/testing it anyway
> you may try to remove long standing duplication/obfuscation:
> 
> 	/* Those fields are duplicating what is in hwif. We currently
> 	 * can't use the hwif ones because of some assumptions that are
> 	 * beeing done by the generic code about the kind of dma controller
> 	 * and format of the dma table. This will have to be fixed though.
> 	 */
> 	volatile struct dbdma_regs __iomem *	dma_regs;
> 	struct dbdma_cmd*		dma_table_cpu;
> 
> What needs to be done is more-or-less:
> 
> - teaching pmac_ide_init_dma() about hwif->prd_max_{nents,size}
>   and then converting it to use ide_allocate_dma_engine()
> 
> - pmif->dma_regs -> hwif->dma_base
> 
> - pmif->dma_table_cpu -> hwif->dmatable_cpu
> 
> - sticking ide_release_dma_engine() somewhere (it seems that
>   pmac driver never frees DMA memory allocated currently)

I'll have a look. Can't promise I'll get it all done this week tho. I
have several other urgent things on my plate.

> Of course while the above would be a nice cleanup+fixup, making
> the driver work comes first..

Heh, we'll see... ide-pmac was never quite intended as a module and
definitely not a module you can remove. I don't know if it's worth
fixing to be honest.

Cheers,
Ben.

> Thanks,
> Bart