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SubjectRe: DMA conflicts with soundcard for ide driver via82cxxx
On Tue, 1 Jan 2002, Vojtech Pavlik wrote:

> On Tue, Jan 01, 2002 at 11:03:52PM +0100, Edward Stempel wrote:
> > In my BIOS-setup there is an option "PCI latency" which defaults to
> > 32. First I changed it to 128. That worked perfect. Later I have decreased
> > it to 64, 48 and 40. But 40 still gave some problems (a little bit
> > distortion of my sound). After that I tried 44, but the disk was to slow
> > with this setting (30 MB/s instead of 40 MB/s). So now I have a PCI
> > latency of 48. The strange thing is that it seems not to work
> > directly. After the system boot when I do hdparm -t, I get about 5
> > MB/s. But then when I switch using_dma off and on again using hdparm, I
> > get the full 40 MB/s and no distortion of my es1371. Any ideas what might
> > cause this?
>
> You'd have to tell me all other settings in your setup first so I can
> guess the cause. What options do you use? Is DMA enabled automatically?
> Etc, etc ...

I am not sure which settings you need. But I compiled a kernel with:
- Generic PCI IDE chipset support
- Sharing PCI IDE interrupt support
- Generic PCI bus-master DMA support
- Use PCI DMA by default when available
- VIA82CXXX chipset support

After booting this kernel hdparm -v reports that I am using dma, but
hdparm -t only reports about 5 MB/s data transfer rate. When I switch the
using of dma off and on with hdparm -d the transfer rate becomes about
40MB/s

The PCI latency is set in the BIOS setup, and according to /proc/pci this
latency is applied to all PCI devices except my matrox G550 video card,
which has a latency of 64.


I hope this explains something.



>
> >
> > Regards,
> >
> > Edward
> >
> >
> >
> >
> > ---------- Forwarded message ----------
> > Date: Tue, 1 Jan 2002 18:14:41 +0100
> > From: Vojtech Pavlik <vojtech@suse.cz>
> > To: Edward Stempel <eazstempel@cal009001.student.utwente.nl>
> > Cc: linux-kernel mailinglist <linux-kernel@vger.kernel.org>
> > Subject: Re: DMA conflicts with soundcard for ide driver via82cxxx
> >
> > On Fri, Dec 28, 2001 at 05:10:43PM +0100, Edward Stempel wrote:
> >
> > > Excellent! That solved my problem.
> >
> > What exactly did you have to change? It might be worth to include the
> > changing of the latency setting in the kernel.
> >
> > >
> > > Thankx
> > >
> > > Edward
> > >
> > >
> > >
> > >
> > > Date: Fri, 28 Dec 2001 10:15:05 +0100
> > > From: Vojtech Pavlik <vojtech@suse.cz>
> > > To: Edward Stempel <eazstempel@cal009001.student.utwente.nl>
> > > Cc: linux-kernel mailinglist <linux-kernel@vger.kernel.org>
> > > Subject: Re: DMA conflicts with soundcard for ide driver via82cxxx
> > >
> > > On Fri, Dec 28, 2001 at 03:32:34AM +0100, Edward Stempel wrote:
> > >
> > > > I have an Asus a7v266 mother board and an Ensoniq sound card in it.
> > > > The ide chipset is a VIA VT8233 that is capable of UDMA100. So I built a
> > > > kernel with the es1371 sound driver and the via82cxxx ide driver
> > > > configured in it. Actually I tried the kernel 2.4.17 first, and the latest
> > > > I tried is 4.5.1 with the latest patch (patch-2.5.2-pre3) applied to it.
> > > > I also tried the kernel 2.5.1 with Vojtech patch (via-3.33.diff from
> > > > his email dated 2001-12-23 23:20:48) applied to it, with the same
> > > > (negative) results.
> > > >
> > > > The good thing is that hdparm reports appr. 40 MB/sec when using DMA and
> > > > about 6 MB/sec when not using DMA.
> > > > Unfortunately using DMA for ide results in some ugly distortion of the
> > > > sound from my soundcard whenever some IO to the disk is done. :((
> > > >
> > > > I have assigned different interrupts to the PCI-cards (ide is
> > > > on-board) and I even changed the sound card's PCI slot, so it shared
> > > > its interrupt with another device (acpi instead of USB). It did not solve
> > > > the problem. Because the problem only occurs when switching on using_dma
> > > > on the ide driver, I think it is a DMA problem with the ide driver. It may
> > > > be the es1371 driver as well off course, but I suspect it is the ide
> > > > driver (or chipset).
> > > >
> > > > Reading the list archive from linux-kernel, I discovered there have been
> > > > more problems with DMA using this chipset, but I did not find anyone
> > > > having the same problem as I have now.
> > > >
> > > > Has someone also dealt with these problems, or can someone help me
> > > > solving this problem? Please help!
> > > >
> > > > Below are some outputs using kernel 5.1 with patch-2.5.2-pre3.
> > >
> > > You may try changing the PCI latency settings on either the IDE
> > > controller or the sound card. Other than that, I don't know how to help.
> > >
> > > --
> > > Vojtech Pavlik
> > > SuSE Labs
> >
> > --
> > Vojtech Pavlik
> > SuSE Labs
>
>


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