On Thursday 22 January 2009 10:58:18 am Jean Schurger wrote:
> I have a video card with a small iommu (in an intel poulsbo) who needs
> to have an PCI resource address aligned to 256M.
>
> 00:02.0 VGA compatible controller: Intel Corporation System Controller
> Hub (SCH Poulsbo) Graphics Controller (rev 07) (prog-if 00 [VGA
> controller])
>
> ...
> Region 0: Memory at fdf00000 (32-bit, non-prefetchable) [size=512K]
> Region 1: I/O ports at ff00 [size=8]
> Region 2: Memory at d8000000 (32-bit, non-prefetchable) [size=128M]
> Region 3: Memory at fdfc0000 (32-bit, non-prefetchable) [size=128K]
> ...
>
> The driver get the address by
> pg->gatt_start = pci_resource_start(dev->pdev, PSB_GATT_RESOURCE); with
> PSB_GATT_RESOURCE=2
Hi Jean,
The BAR is only 128M in size. I don't know of a way for a PCI device
to specify that a BAR needs to be aligned on anything larger than its
size. Are you *sure* it has to be 256M-aligned?
Maybe the card comes in 128M and 256M versions, and the driver
incorrectly assumes all cards are 256M?
> and test it here :
>
> if (pg->gatt_start & 0x0FFFFFFF) {
> DRM_ERROR("Gatt must be 256M aligned. This is a
> bug.\n");
> ret = -EINVAL;
> goto out_err;
> }
>
> The only 'place' where the resource can be aligned to 256M is at
> 0xe0000000 who is reserved by 'pnp'
>
> How can i 'move' this region to 0xe000000 ?
If the region at 0xe0000000 is really in use by some PNP device,
it would be a bad idea to move the VGA device there, too. PCI
drivers normally just use the resources allocated by the BIOS or
the PCI core.
Bjorn
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