Re: [PATCH][VTD] fixed a timing issue on DELL calpella laptop while doing graphics pass-through

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Sat, Jun 05, 2010 at 09:40:10AM +0100, Jean Guyader wrote:
> On Fri, Jun 04, 2010 at 09:30:40PM +0100, Konrad Rzeszutek Wilk wrote:
> > > Yes, to take more time to do an FLR on those platform, but I don't think
> > > this is a proper fix. The fix we have for that in our tree (XCI) is to make
> > > sure the value we write when we restore the pci config space stick in
> > > pciback.
> > > 
> > > I'll send the patch later today,
> > 
> > Please send it to me as well so I can stick in the proper pv-ops tree.
> 
> Thanks Konrad.
> 
> Here is the patch for a 2.6.27 kernel.

I seem to be missing a wealth of previous checkins. There is no 
pciback_reload_config_space in the pciback code that I pulled from
2.6.18.

If you could re-base against Jeremy's PV-OPS kernel and send those
patches that would be tremendously helpful.

Here is a Wiki that explains in detail how to get the PV-OPS kernel and
build it: http://wiki.xensource.com/xenwiki/XenParavirtOps

Much appreciated!
> 
> pciback: Verify write when restoring the pci config space after FLR
> 
> Signed-off-by: Jean Guyader <jean.guyader@eu.citrix.com>

> diff --git a/drivers/xen/pciback/pciback_ops.c b/drivers/xen/pciback/pciback_ops.c
> index 2b77b31..62267e3 100644
> --- a/drivers/xen/pciback/pciback_ops.c
> +++ b/drivers/xen/pciback/pciback_ops.c
> @@ -56,11 +56,20 @@ void pciback_reload_config_space(struct pci_dev *dev)
>  	struct pciback_dev_data *dev_data = pci_get_drvdata(dev);
>  	u32 *ptr = (u32*)dev_data->cfg_space;
>  	int i, val, count = dev->cfg_size/sizeof(u32);
> +        int limit = 0;
>  
>  	for (i = 0; i < count; i += sizeof(u32), ptr++) {
>  		pci_read_config_dword(dev, i, &val);
> -		if (val != *ptr)
> +		while (limit < 1000 && val != *ptr)
> +                {
>  			pci_write_config_dword(dev, i, *ptr);
> +                        pci_read_config_dword(dev, i, &val);
> +                        mdelay(1);
> +                        limit++;
> +                }
> +                if (limit == 1000)
> +                    printk(KERN_ERR "pciback: Error reloading config space after flr dev:%x offset:%x\n",
> +                            dev->devfn, i);
>  	}
>  }
>