Bug in vr(4) driver
John Baldwin
jhb at freebsd.org
Wed Oct 10 13:37:35 PDT 2007
On Monday 27 August 2007 09:03:10 pm Pyun YongHyeon wrote:
> On Mon, Aug 27, 2007 at 08:18:08PM +0000, Bill Paul wrote:
> >
> > I recently started writing a driver for the Via Rhine family of chips
> > for VxWorks (they turn up on various x86-based single board systems,
> > and I figured it'd be nice to actually support them out of the box),
> > and along the way, I noticed a subtle bug in the FreeBSD vr(4) driver.
> >
> > The vr_attach() routine unconditionally does this for all supported
> > chips:
> >
> > /*
> > * Windows may put the chip in suspend mode when it
> > * shuts down. Be sure to kick it in the head to wake it
> > * up again.
> > */
> > VR_CLRBIT(sc, VR_STICKHW, (VR_STICKHW_DS0|VR_STICKHW_DS1));
> >
> > The problem is, the VR_STICKHW register is not valid on all Rhine
> > devices. The VT86C100A chip, which is present on the D-Link DFE-530TX
> > boards, doesn't support power management, and its register space is
> > only 128 bytes wide. The VR_STICKHW register offset falls outside this
> > range. This may go unnoticed in most scenarios, but if you happen to have
> > another PCI device in your system which is assigned the register
> > space immediately after that of the Rhine, the vr(4) driver will
> > incorrectly stomp it. In my case, the BIOS on my test board decided
> > to put the register space for my PRO/100 ethernet board right next
> > to the Rhine, and the Rhine driver ended up clobbering the IMR register
> > of the PRO/100 device. (Long story short: the board kept locking up on
> > boot. Took me the better part of the morning suss out why.)
> >
> > The strictly correct thing to do would be to check the PCI config space
> > to make sure the device supports the power management capability and only
> > write to the VR_STICKHW register if it does. A less strictly correct
> > but equally effective thing to do would be:
> >
> > /*
> > * Windows may put the chips that support power management into
> > * suspend mode when it shuts down. Be sure to kick it in the
> > * head to wake it up again.
> > */
> > if (pci_get_device(dev) != VIA_DEVICEID_RHINE)
> > VR_CLRBIT(sc, VR_STICKHW, (VR_STICKHW_DS0|VR_STICKHW_DS1));
> >
> > This is basically the fix I put into my VxWorks driver. I suggest someone
> > update the FreeBSD driver as well.
> >
>
> Hi,
>
> I don't have vr(4) hardwares(if I had I would have converted vr(4)
> to use bus_dma(9)). Would you review/test the attached patch?
Pyun,
I'd say to go ahead and commit the patch.
--
John Baldwin
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