Messages in this thread | | | Date | Tue, 2 May 2006 09:21:36 -0700 | From | Greg KH <> | Subject | Re: Add a "enable" sysfs attribute to the pci devices to allow userspace (Xorg) to enable devices without doing foul direct access |
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On Tue, May 02, 2006 at 10:14:45AM -0600, Bjorn Helgaas wrote: > On Saturday 29 April 2006 03:04, Dave Airlie wrote: > > > > > This patch adds an "enable" sysfs attribute to each PCI device. When read it > > > shows the "enabled-ness" of the device, but you can write a "0" into it to > > > disable a device, and a "1" to enable it. > > > > > > This later is needed for X and other cases where userspace wants to enable > > > the BARs on a device (typical example: to run the video bios on a secundary > > > head). Right now X does all this "by hand" via bitbanging, that's just evil. > > > This allows X to no longer do that but to just let the kernel do this. > > > > > > Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> > > > CC: Peter Jones <pjones@redhat.com> > > > CC: Dave Airlie <airlied@linux.ie> > > > > ACK > > > > This would allow me to remove the issue in X where loading the DRM at X > > startup acts differently than loading the DRM before X runs, due to Xs PCI > > probe running in-between... with this I can just enable all VGA devices > > and no worry whether they have a DRM or not.. > > This sysfs "enable" patch seems like goodness. > > But I hope that when X uses this, it only enables & disables VGA > devices it's actually using. In the past, it seems like X has > blindly disabled *all* VGA devices in the system, even though > they might be in use by another X server. I'm sure that's all > well-understood and cleaned up now; just wanted to make sure > this nightmare didn't recur.
Hopefully with the recent PCI changes to X, this will not happen. If it does, that's a big bug in X :)
thanks,
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