Re: PCI probe leaves master abort disabled in PCI_BRIDGE_CONTROL

[Greg KH <gregkh@suse.de>]

On Mon, Feb 13, 2006 at 05:13:21PM -0800, David S. Miller wrote:
> 
> In drivers/pci/probe.c:pci_scan_bridge(), if this is not the first
> pass (pass != 0) we don't restore the PCI_BRIDGE_CONTROL_REGISTER and
> thus leave PCI_BRIDGE_CTL_MASTER_ABORT off:
> 
> int __devinit pci_scan_bridge(struct pci_bus *bus, struct pci_dev * dev, int max, int pass)
> {
>  ...
> 	/* Disable MasterAbortMode during probing to avoid reporting
> 	   of bus errors (in some architectures) */ 
> 	pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &bctl);
> 	pci_write_config_word(dev, PCI_BRIDGE_CONTROL,
> 			      bctl & ~PCI_BRIDGE_CTL_MASTER_ABORT);
>  ...
> 	if ((buses & 0xffff00) && !pcibios_assign_all_busses() && !is_cardbus) {
> 		unsigned int cmax, busnr;
> 		/*
> 		 * Bus already configured by firmware, process it in the first
> 		 * pass and just note the configuration.
> 		 */
> 		if (pass)
> 			return max;
>  ...
> 	}
> 
> 	pci_write_config_word(dev, PCI_BRIDGE_CONTROL, bctl);
>  ...
> 
> This doesn't seem intentional.

No it doesn't.  Ralf added that code, way back in 2.6.2-rc2, with a
patch description of "[PATCH] PCI: fix probing for some mips systems"

David, does this break some stuff on your boxes?

Ralf, any thoughts?  It was way back in January of 2004 that this change
went in.

thanks,

greg k-h