# \[PATCH V2 2/2\] efi/fb: Convert PCI bus address to resource if translated by the bridge

- From: Bartlomiej Zolnierkiewicz \<hidden\>
- Date: 2018-06-22 10:11:22 
- List: linux-arm-kernel
- Page: https://ratatoskr.run/linux-arm-kernel/2018/06/5314456
- Thread: https://ratatoskr.run/linux-fbdev/2018/05/5287459/t.md

```text
On Friday, June 22, 2018 12:07:48 PM Bartlomiej Zolnierkiewicz wrote:
> On Friday, June 22, 2018 09:54:22 AM Ard Biesheuvel wrote:
> > On 13 June 2018 at 18:08, Bartlomiej Zolnierkiewicz
> > [ref] wrote:
> > > On Wednesday, June 13, 2018 05:45:48 PM Ard Biesheuvel wrote:
> > >> On 18 May 2018 at 16:17, Sinan Kaya [ref] wrote:
> > >> > A host bridge is allowed to remap BAR addresses using _TRA attribute in
> > >> > _CRS windows.
> > >> >
> > >> > pci_bus 0000:00: root bus resource [mem 0x80100100000-0x8011fffffff window] (bus address [0x00100000-0x1fffffff])
> > >> > pci 0000:02:00.0: reg 0x10: [mem 0x8011e000000-0x8011effffff]
> > >> >
> > >> > When a VGA device is behind such a host bridge and the resource is
> > >> > translated efifb driver is trying to do ioremap against bus address
> > >> > rather than the resource address and is failing to probe.
> > >> >
> > >> > efifb: probing for efifb
> > >> > efifb: cannot reserve video memory at 0x1e000000
> > >> > efifb: framebuffer at 0x1e000000, using 1920k, total 1875k
> > >> > efifb: mode is 800x600x32, linelength=3200, pages=1
> > >> > efifb: scrolling: redraw
> > >> > efifb: Truecolor: size=8:8:8:8, shift=24:16:8:0
> > >> >
> > >> > Use the host bridge offset information to convert bus address to
> > >> > resource address in the fixup.
> > >> >
> > >> > Signed-off-by: Sinan Kaya <redacted>
> > >>
> > >> Reviewed-by: Ard Biesheuvel <redacted>
> > >>
> > >> Bartlomiej, could you please take these via the fbdev tree for v4.19?
> > >
> > > Sure, I will queue it after the current merge window.
> > >
> > >> Peter already gave his ack but Sinan dropped it (presumably because of
> > >> the split in v2)
> > >
> > > Peter, can I (re)add your ACK to V2 patches?
> > >
> > 
> > Actually, it would be better if we could take this through the EFI
> > tree instead, with your ack. Would you mind?
> 
> Fine with me.

Acked-by: Bartlomiej Zolnierkiewicz <redacted>

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics
```