Re: Add a "enable" sysfs attribute to the pci devices to allowuserspace (Xorg) to enable devices without doing foul direct access

From: Dave Airlie
Date: Sat Apr 29 2006 - 05:04:12 EST




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@xxxxxxxxxxxxxxx>
CC: Peter Jones <pjones@xxxxxxxxxx>
CC: Dave Airlie <airlied@xxxxxxxx>

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..

Dave.

--
David Airlie, Software Engineer
http://www.skynet.ie/~airlied / airlied at skynet.ie
Linux kernel - DRI, VAX / pam_smb / ILUG

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