[parisc-linux] C3000 and IDE DMA support

[Alan Cox]

On Maw, 2003-08-26 at 12:46, M. Grabert wrote:
> - the hard disk performs very bad (just 3.13 MB/s instead of expected
>   >30 MB/s, tested with similar drive in PC and same hdparm settings)
>   In fact it shows typical data rates for unsupported DMA transfers

Your drive is in PIO, probably PIO3 or so.

> - excessive harddisk access, ie. copying large files (>1GB) obviously
>   blocks any other access to the harddisk, at least it's not (very) responsive
>   (caused by the slow transfer rate?)

Hard to tell

> - can't change from my default kernel setting (DMA) to PIO mode via hdparm,
>   it causes a kernel oops (but hey, who needs PIO anyway ;)

That would be a bug

> Is unmasq_irq supported? What about DMA? Is it obviously not fixed yet
> (at least somebody wrote that "ns87415 dma doesn't work reliably on
>  suckyio-systems" a couple of weeks back)

irq unmasking is a generic IDE property so should be fine on any
platform with a non prehistoric defunct controller (NS87415 is fine)

> Any hints how to speed up the transfer rate?

Buy a PC ;)

Basically you need to fix DMA support