enable/disable devices behavior

[Dave Airlie]

On Wed, 2009-05-06 at 01:37 -0300, Tiago Vignatti wrote:
> Hi,
> 
> AFAIK, the existing interface in libpciaccess to enable a device 
> (pci_device_enable) deals always with I/O _and_ memory resources. But 
> I'm confused with the behavior of such interface because it's not 
> working as I expected. For me it has to be equivalent to do the 
> following, in the regs configuration space:
> 
>      ctrl = (PCI_COMMAND_IO | PCI_COMMAND_MEMORY);
>      pci_device_cfg_write_u32(dev, ctrl, PCI_COMMAND);
> 
> 
> Isn't it? But it's not happening that. When I call pci_device_enable (or 
> just `echo 1 > enable` in device) the kernel sometimes sets only the 
> PCI_COMMAND_MEMORY bit or simply does nothing. What am I missing here?
> 
> Attached, I'm sending a code that I'm using to play with this.

Its not for that.

Twiddling enable bits from userspace isn't something we want to be able
to do.

Dave.