Re: [patch] VIA 4.2x driver for 2.2 kernels

[Vojtech Pavlik]

On Tue, Feb 20, 2001 at 11:15:02PM -0800, Shane Wegner wrote:
> On Wed, Feb 21, 2001 at 08:09:19AM +0100, Vojtech Pavlik wrote:
> > On Tue, Feb 20, 2001 at 03:59:27PM -0800, Shane Wegner wrote:
> > 
> > > > You wanted my VIA driver for 2.2. Here is a patch that brings the very
> > > > latest 4.2 driver to the 2.2 kernel. The patch is against the
> > > > 2.2.19-pre13 kernel plus yours 1221 ide patch.
> > > 
> > > This drivers breaks with my HP 8110 CD-R drive.  It's
> > > sitting on primary slave of a Via 686B controler.  When I
> > > try to do a hdparm -d1 -u1 -k1 /dev/hdb, the kernel locks
> > > up hard.  Not even an oops.  Reverting to the old driver
> > > works fine.
> > 
> > Don't do that. Use the kernel option to enable DMA instead.
> > 
> > Hmm, I'll have to look into this anyway - many users seem to do that
> > and it isn't as harmless as it looks (it worked by pure luck with
> > the previous version).

> Ok, can I still use -u1 -k1 -c1 on the drives or is it even
> necessary anymore.

If you enable automatic DMA in the kernel config, it isn't necessary at
all. The VIA driver sets up everything.

> Is the deprecation of -d1 VIA IDE
> specific or does it apply to the entire subsystem.

Well, in my opinion it was always a potentially dangerous option and so
it remains. I'll update the VIA driver to make sure its not dangerous
at least with it anymore.

Scenario:

1) AutoDMA not enabled
2) VIA sets PIO mode on boot
3) User enables DMA -> IDE driver starts using dma
4) But VIA is still set to PIO mode

I'll have to make the VIA driver check when IDE dma is enabled, test
whether the chipset was already programmed for it and program the
chipset for it if needed.

-- 
Vojtech Pavlik
SuSE Labs