DMA no active on HL-DT-STCD-RW/DVD

[Marcin Jessa]

On Sat, 13 May 2006 19:19:30 +0300 (EEST)
Dmitry Pryanishnikov <dmitry at atlantis.dp.ua> wrote:

> 
> Hello!
> 
> On Sat, 13 May 2006, Angka H. K. wrote:
> > By the way what is WDMA and why it saying PIO not WDMA ?
> 
>   WDMA corresponds to so-called "multiword DMA" transfer mode. It's slower than
> UDMA (IIRC WDMA2 gives 16Mbytes/s, same as PIO4), but still should be 
> sufficient for CD/DVD drive (well, up to 8x-speed DVDs). Of course, it's 
> better to use WDMA2 than PIO4 because WDMA (as well as UDMA) doesn't use
> CPU cycles for moving data between RAM and device. FreeBSD's ata driver
> is quite conservative, and doesn't automatically enable WDMA mode for
> ATAPI device even if hw.ata.atapi_dma=1, so you should just enable
> this mode with atacontrol. E.g., you can add

Does this mean I should set my laptop's drive mode to WDMA2 instead of
UDMA100 (HD) and UDMA33 (CDRW)?

Marcin.