ATAPI DVD-Drive is slow, but can't set dma: HDIO_SET_DMA failed: Operation not permitted

[Gerhard Gaußling]

Hello All,

I use Hoary 5.04 for amd64 architecture. I got an ASUS A8N-SLI Deluxe 
motherboard with amd64 3500+, 1GiB RAM, and an LG Electrionics HL-DT-ST 
DVDRAM GSA-4163B.
When playing a DVD the CPU load is by 25% and the cool'n'quiet stepped 
the cpu speed at 1,8GHZ.

I can use scsi emulation and ide-cd. I set now the system to use the 
DVD-drive with the recommended ide-cd, because I wanted to see if that 
driver speeds up the drive, and set the dma for the drive.

But I get the error message "HDIO_SET_DMA failed: Operation not 
permitted"

Here's the output

$ sudo hdparm -i /dev/hdc
/dev/hdc:

 Model=HL-DT-ST DVDRAM GSA-4163B, FwRev=A100, SerialNo=K574BG82620
 Config={ Fixed Removeable DTR<=5Mbs DTR>10Mbs nonMagnetic }
 RawCHS=0/0/0, TrkSize=0, SectSize=0, ECCbytes=0
 BuffType=unknown, BuffSize=0kB, MaxMultSect=0
 (maybe): CurCHS=0/0/0, CurSects=0, LBA=yes, LBAsects=0
 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
 PIO modes:  pio0 pio3 pio4
 DMA modes:  mdma0 mdma1 mdma2
 UDMA modes: udma0 udma1 *udma2
 AdvancedPM=no
 Drive conforms to: device does not report version:

 * signifies the current active mode

That point (*)  I don't understand, because hdparm says that dma is off:

$ sudo hdparm -d /dev/hdc

/dev/hdc:
 using_dma    =  0 (off)

and I can't set it to "on"
$ sudo hdparm -d1 /dev/hdc

/dev/hdc:
 setting using_dma to 1 (on)
 HDIO_SET_DMA failed: Operation not permitted
 using_dma    =  0 (off)

So the DVD is to slow to look DVD Videos without flickering and flaws, 
but the specs of the drive are looking good:

Read Speed (CD-ROM) : Max 40x
Read Speed (DVD-ROM) : Max 16x
Data Transfer Rate(CD) : Max 6,000KB/s, DVD: Max 22.16 Mbytes/s

I didn't reach 22.16 Mbytes with hdparm:

$ sudo hdparm -tT /dev/hdc

/dev/hdc:
 Timing cached reads:   3620 MB in  2.00 seconds = 1809.37 MB/sec
 Timing buffered disk reads:   12 MB in  3.10 seconds =   3.87 MB/sec

cdrecord also mentioned some issues (scsi emulation):
Using generic SCSI-3/mmc   CD-R/CD-RW driver (mmc_cdr).
Driver flags   : MMC-3 SWABAUDIO BURNFREE 
Supported modes: TAO PACKET SAO SAO/R96P SAO/R96R RAW/R16 RAW/R96P 
RAW/R96R
Drive buf size : 1053696 = 1029 KB
Drive DMA Speed: 3648 kB/s 20x CD 2x DVD
FIFO size      : 4194304 = 4096 KB
/usr/bin/cdrecord: Operation not permitted. WARNING: Cannot set 
RR-scheduler
/usr/bin/cdrecord: Permission denied. WARNING: Cannot set priority using 
setpriority().
/usr/bin/cdrecord: WARNING: This causes a high risk for buffer 
underruns.
/usr/bin/cdrecord: DMA speed too slow (OK for 16x). Cannot write at 
speed 40x.

And in fact I had some failed burnings with burnproof on.

My Kernel .config is:
$ grep IDEDMA /usr/src/linux/.config20050506-1
CONFIG_BLK_DEV_IDEDMA_PCI=y
# CONFIG_BLK_DEV_IDEDMA_FORCED is not set
CONFIG_IDEDMA_PCI_AUTO=y
CONFIG_IDEDMA_ONLYDISK=y
CONFIG_BLK_DEV_IDEDMA=y
# CONFIG_IDEDMA_IVB is not set
CONFIG_IDEDMA_AUTO=y
CONFIG_SCSI_SATA_NV=m
CONFIG_BLK_DEV_AMD74XX=m

Should I set CONFIG_BLK_DEV_AMD74XX to Y and 
CONFIG_IDEDMA_ONLYDISK to No?

My /etc/mkinitrd/modules is empty should I load the chipset driver 
modules into initrd?
This is my /etc/modules:
sg
sr_mod
#ide_scsi
ide-cd
ide-disk
ide-generic
lp
mousedev
psmouse
rtc
sbp2

Help is much appreciated

Kind regards

Gerhard