I am at a point of total frustration in figuring out whether and how to enable DMA on an optical drive. I am running the Debianized flavour of kernel 2.6.10 and the installation tracks Debian sid/unstable. As far as I understand, the problems surrounding the configuration of optical writers as IDE ATA(PI) devices and enabling DMA under kernel 2.6 are largely resolved, even though there is no resolution in sight to the disagreement between the kernel team and the author of cdrecord. At the level of one, however, I am having little success. I continue to suffer all the bad effects of no DMA. Although the overall machine is powerful (P4 @ 2.4GHz, 1GB RAM) DVD playback is choppy. cdrecord complains that "DMA speed too slow (OK for 11x). Cannot write at 24x" (the burner spec is write CD-R at 24x). But the customary command to enable DMA ("hdparm -d1 /dev/hde") does evil things. Disks cannot be mounted and it takes minutes if not hours for the mount command to error out. The writer in question is a combination CD/DVD RW. It is the fifth IDE device in my box and is connected through a 2001-vintage Promise PDC20267 Ultra ATA100 PCI controller card. I believe that the kernel and modules are correctly configured to support DMA to optical devices: CONFIG_IDE=y CONFIG_BLK_DEV_IDE=y CONFIG_BLK_DEV_IDEDISK=y CONFIG_IDEDISK_MULTI_MODE=y CONFIG_BLK_DEV_IDECD=y CONFIG_IDE_GENERIC=y CONFIG_BLK_DEV_IDEPCI=y CONFIG_IDEPCI_SHARE_IRQ=y CONFIG_BLK_DEV_GENERIC=y CONFIG_BLK_DEV_IDEDMA_PCI=y CONFIG_IDEDMA_PCI_AUTO=y CONFIG_BLK_DEV_PIIX=y CONFIG_BLK_DEV_PDC202XX_OLD=y CONFIG_PDC202XX_BURST=y CONFIG_BLK_DEV_IDEDMA=y CONFIG_IDEDMA_AUTO=y bruce@bruce_P4:~$ su -c 'hdparm /dev/hde' Password: /dev/hde: IO_support = 0 (default 16-bit) unmaskirq = 0 (off) using_dma = 0 (off) keepsettings = 0 (off) readonly = 0 (off) readahead = 256 (on) HDIO_GETGEO failed: Invalid argument bruce@bruce_P4:~$ su -c 'hdparm -i /dev/hde' Password: /dev/hde: Model=HL-DT-ST DVDRAM GSA-4082B, FwRev=A201, SerialNo=K2H434I5524 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 Questions: 1. Is there a way to enable DMA safely for all operations with this DVD/CD drive, particularly burning, video DVD playback, data disk reading? 2. If the answer to q1 is no, is it OK to enable DMA ("hdparm -d1 /dev/hde") for burning disks and for watching DVDs, but to disable it again before mounting data disks? 3. For an optical disk (as opposed to a hard disk), is it important to use an 80-connector IDE cable with the ATA100 controller as opposed to the traditional 40-connector cable? I have RTFM'ed and STFW'ed to the point of information overload. If there are good resources out there that I have missed, please point me to them. Help much appreciated. It is a testament to how solid this system is that this is my biggest current problem. -- Bruce Miller Ottawa, ON K1M 2H9 CANADA GPG key ID 0x1B9200FC. Public key available from keyservers
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