Messages in this thread | | | Date | Mon, 19 Dec 2005 16:46:55 +0100 | From | Bartlomiej Zolnierkiewicz <> | Subject | Re: IDE: PDC20275 turning on/off DMA dangerous? |
| |
On 12/19/05, Clemens Koller <clemens.koller@anagramm.de> wrote: > Hello, Bartolmiej! > > >>I am working on an embedded ppc (mpc8540) using a pretty common Promise IDE > >>PCI controller w/ a PDC20275 on it (it's called Ultra TX2). > >>I have an otherwise good Maxtor 6B120P0 (160GB) connected to it. > >> > >>But sometimes (expecially with more than zero disk-i/o-load), when I > >>turn on DMA by > >> > >>$hdparm -X69 -d1 /dev/hda > >>I get > >> > >>hda: task_out_intr: status=0x58 { DriveReady SeekComplete DataRequest } > >>ide: failed opcode was: unknown > >>hda: CHECK for good STATUS > >> > >>And when I turn off DMA with > >>$hdparm -d0 /dev/hda > >>I get sometimes a > >> > >>hda: DMA disabled > >> > >>which is fine but sometimes I also get: > >> > >>hda: status error: status=0x58 { DriveReady SeekComplete DataRequest } > >>ide: failed opcode was: unknown > >>hda: drive not ready for command > >>hda: CHECK for good STATUS > >> > >>which is not so nice. > >>Can you tell me if this is dangerous? > > > > > > Is there any particular reason why you are using hdparm with '-d' and '-X'? > > I want to test it with DMA before fixing it into the kernel. > > > Your IDE host driver (pdc202xx_new in this case) should configure > > best xfer mode and enable DMA so you shouldn't need to use hdparm. > > I didn't enable automatic turning on of DMA it in the kernel by default > in the past because I had problems with this hdd controller and > interrupts (some PCI IRQ mapping issues). The interrupt issues are > solved now, so I've tried to enable DMA. DMA works pretty fine, > I was just worried about the severity of the message. It doesn't > really tell anything useful for non-ide-hackers. (whether it's > dangerous or not.) > > > Given that IDE driver code for changing xfer mode and DMA setting > > is racy and actually quite hard to fix, it will probably be removed in > > the future (after auditing IDE host drivers). > > So, I guess the answer is: DMA itself seems to work and it > isn't really dangerous - it's working as it's supposed to.
Yes.
> But if you do it the way you do, you can run into problems due > to races. Right? So, if I enable DMA as usual in the kernel, > I don't usually risk my data?!
Yes, just use default settings.
Thanks, Bartlomiej - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |