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

[Dmitry Pryanishnikov]

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

/sbin/atacontrol mode acd0 wmda2

to your /etc/rc.local file.

Sincerely, Dmitry
-- 
Atlantis ISP, System Administrator
e-mail:  dmitry at atlantis.dp.ua
nic-hdl: LYNX-RIPE