DMA on ht6560b?

DMA on ht6560b?

[Jan Evert van Grootheest]

Hi,

With digging into the code...

I think the ht6560b controller supports DMA. At least it did so in 2.2 
(where hdparm could still turn it on). DMA in 2.2 would improve the HD 
from about 1M/s to 4M/s. So that's quite interesting.
Also the datasheet claims that there is full ANSI ATA-4a support. 
According to the ATA table on wikipedia that should include up to mwdma 
2 and udma33.

What's the magic that will turn it on for the ht6560b controller?
I would guess at the [sm]wdma_mask fields in hwif_t? Plus something for 
set_dma_mode?
Some help would be appreciated.

Thanks,
Jan Evert

Re: DMA on ht6560b?

[Alan Cox]

> I think the ht6560b controller supports DMA. 

The data sheet doesn't. It's a PIO controller capable of PIO4 with 32bit
host to cpu transfers are best.

Re: DMA on ht6560b?

[Jan Evert van Grootheest]

Alan Cox wrote:
>> I think the ht6560b controller supports DMA. 
>>     
>
> The data sheet doesn't. It's a PIO controller capable of PIO4 with 32bit
> host to cpu transfers are best.
>   

Hmm. But what do you then think that 2.2 did?
I mean it now does 1.15M/s and in 2.2 it would do ~4M/s with DMA on. 
Were those perhaps ISA style DMA transfers (as opposed to BM-DMA)?
I really should compile a 2.2 with ht6560b support...

Thanks for answering, though, I don't know that much about ATA.
Jan Evert

Re: DMA on ht6560b?

[Alan Cox]

> Hmm. But what do you then think that 2.2 did?

PIO4

> I mean it now does 1.15M/s and in 2.2 it would do ~4M/s with DMA on. 

It's never done DMA.